Advice
Gardener's Calendar - May
Fruit, vegetable & herb garden
Flower garden
Glasshouse, conservatory and houseplants
Trees, shrubs, roses, climbers and hedges
Lawns and meadows
Ponds
Wildlife gardening
Garden structures
Gardening for children
Top 10 jobs
1. Watch out for late frosts. Protect tender plants
2. Earth up potatoes, and promptly plant any still remaining
3. Plant out summer bedding at the end of the month (except in cold areas)
4. Collect rainwater and investigate ways to recycle water for irrigation
5. Regularly hoe off weeds
6. Open greenhouse vents and doors on warm days
7. Mow lawns weekly
8. Check for nesting birds before clipping hedges
9. Lift and divide overcrowded clumps of daffodils and other spring-flowering bulbs
10. Watch out for viburnum beetle and lily beetle grubs
May's weather
Glossary of terms
Bark ringing
Blossom/fruit thinning
Catch crop
Earthing up
Hardening off
Scion
Successional
Sucker
Fruit and vegetable garden
Fruit
Tie-in new shoots on fan-trained peaches and nectarines and wall-trained cherries, plums and gages.
Keep wall-trained fruit, especially stone fruit, well watered during fruit set and fruit development. Use rainwater or recycled water wherever possible.
Shorten leaders and sideshoots on over-vigorous wall-trained apples and pears, to weaken their growth and so divert their energy to fruit production rather than shoot growth.
On indoor vines allow only one flower truss to develop on each main lateral coming off the central rod; any others should be removed. Keep flowering laterals short, pinching out their tips of at two leaves past the single flower truss. Non-fruiting laterals can be kept a bit longer, pinching out the tips after five leaves have formed. Any side shoots branching off the main laterals should be stopped at one leaf.
Wall-trained plums and cherries can be pruned this month, as long as the weather is warm enough for them to be in full, active growth. If pruned while still dormant, they run the risk of getting silver leaf disease. Any branches coming out from the wall should be removed entirely.
For wall-trained sweet cherries, pinch out the growing tip of each branch, once it has grown six new leaves. After fruit picking, the shoots can be cut back again, removing half of this year’s new growth, and removing any overcrowded or unhealthy looking stems at the same time.
For wall-trained ‘Morello’ and acid cherries, prune out entirely any fruited shoots, removing all of this year’s new growth. But be careful not to remove any unfruited new shoots, as it is these that will produce fruit next year. Instead, tie them in so that they are easy to pick the following year.
Avoid late frost damage to peaches, nectarines and apricots by covering them with fleece on cold nights. Any protective coverings used against peach leaf curl should be removed by the end of the month (in all but the coldest areas) to allow access by pollinating insects.
Before buds break, remove winter protection from wall-trained figs and prune back older stems to the main trunk or the base to encourage new shoots.
Mulching fruit crops will help them to retain moisture around the roots.
Hoe off or pull out raspberry suckers appearing between rows. Very vigorous plants may also need some selective cane removal, so that there will be sufficient air and light penetration between the branches, and to ensure the plant has enough energy to ripen all the young fruits.
Net soft fruits as they begin to ripen.
Plant out seedlings of alpine strawberries.
Remove strawberry runners before they start to creep along the ground. Leaving them will only sap energy from existing plants, so reducing their yield of fruit. If you need runners in order to have new plants for next year, then pinch off the flowers from a couple of selected plants, encouraging them to produce green shoots and runners (rather than fruits and flowers), which you can save and pot up separately.
Any early strawberry crops that were kept under glass or under fleece and cloches, should now be uncovered (or the greenhouse doors opened fully), to allow access for pollinating insects.
Control weeds to prevent them competing for moisture and nutrients. Hoe regularly between rows on hot days to make sure the weeds dry up and die.
Over-vigorous apple and pear trees can be ring-barked. Heavy crops of blossom can also be thinned, to reduce the numbers of fruits that form with the aim of encouraging more even ripening, better fruit quality, and reduce problems with biennial bearing.
Gooseberry blossom may also be thinned in order to produce a smaller number of large dessert fruits.
Pest & disease watch
By the end of the moth, you should remove any protective coverings used against peach leaf curl that you have kept on peaches, apricots and nectarines over the winter.
Stay alert for gooseberry sawfly damage and the raised red blisters of currant blister aphid.
Do not be overly worried if the leaves on your pear tree start to come up in small pale blisters. This is probably due to the pear leaf blister mite. Although there are no effective pesticides available to amateur gardeners, the damage is not as severe as the plant's appearance may suggest. Infested trees can still produce a good crop of pears.
Blackcurrants are vulnerable to big bud mite (affected buds appear larger than normal). The mites can spread blackcurrant reversion virus. Virus symptoms will be evident once the plant comes into flower, as the flowers look red rather than grey. Affected plants must be dug up and disposed of in the rubbish, or by burning. You may wish to grow resistant varieties such as ‘Farleigh’, ‘Foxendown’ or ‘Ben Hope’.
Dead shoots on tree fruit may indicate a number of disease problems. Check for signs of apple and pear canker, bacterial canker and blossom wilt.
Hang pheromone traps in apple trees to help reduce codling moth numbers. This is the month when they start to mate, so trapping them will reduce the numbers of eggs. You will need one trap for every three to five trees.
Keep an eye out for early aphid attacks, and deal with them appropriately, either by squashing small colonies, or by using pesticides on larger infestations. Remember that very few pesticides have approval for use on edible crops. Derris and pyrethrum are often good choices, but always check the label first for confirmation of approval, safety and effectiveness.
Ensure good air circulation in the greenhouse to reduce risk of Botrytis, powdery mildew and downy mildew on grapes.
American gooseberry mildew can appear as a brown crust over the leaves and fruits of gooseberry bushes. Spraying with fungicides containing sulphur or myclobutanil is usually effective, but you may wish to grow a more resistant variety like ‘Invicta’.
Apples and pears may need spraying against scab, where this has got out of hand in previous years. Fungicides containing mancozeb or myclobutanil are suitable choices.
Look out for powdery mildew, especially during warm dry spells.
Keep watch for signs of cane spot or spur blight on blackberries and hybrid berries. Ensure that any fungicides used have approval for use on edible crops. Sulphur, myclobutanil and mancozeb are often good choices, but always read the label to check for approval, safety and effectiveness before using.
Reduce numbers of rotten strawberries by tucking straw mulch, strawberry matting or similar around the plants, to prevent the fruits from touching the soil or getting too damp. Covering the whole bed with netting will also reduce bird damage.
Never spray pesticides once blossom has opened on fruit crops. They will kill the pollinating insects that you rely on for your crops. When carrying out any spraying operation, take care to spray early in the morning when fewer pollinating insects are about - you only need to kill the pests, not the beneficial insects.
Vegetables
Asparagus is a perennial vegetable. Harvest spears from established plants for six to eight weeks from May into the early summer. Do not harvest spears from crowns less than two years old.
Harvest spring lettuce, spring cabbage, salad onions, salad leaves, beetroot and radishes as they mature. You can continue with successional sowing of salad crops, to ensure an even supply over the season.
Sow French and runner beans, squash, cucumbers and pumpkin seeds directly into prepared beds outside - in colder regions you should wait until the end of the month. Be alert to late frosts (for which a covering of horticultural fleece should provide sufficient protection). French beans are best sown in traditional rows at 15-22cm (6-9in) spacing.
Ridge cucumbers can be sown indoors now, for planting out in early June. Two seeds per pot work well, then selecting the most vigorous seedling from each pot for growing on and planting out.
Sow cauliflowers and purple sprouting broccoli for harvesting next winter.
Try sowing some unusual vegetables such as kohl rabi (like a large white above-ground turnip), scorzonera and salsify (both of which produce edible roots, which are boiled and peeled like parsnip and have been said to taste a bit like oysters).
Brussels sprouts for next winter should now be ready for transplanting after early or mid-spring sowing. The gaps between them can be used for short-term ‘catch crops’ like radishes or 'Little Gem' lettuces, as they will take time to grow into their recommended spacing requirement.
Plant out artichokes that were previously sown under cover. They are tall handsome plants, and the steamed unopened flower buds are considered a delicacy. They can be grown as perennials (in which case they need 90cm/3ft spacing), or as biennials (45cm/18in spacing is sufficient).
After all risk of frost has passed, plant out tomatoes, courgettes and pumpkins that were previously sown under cover.
Self-blanching celery can also be planted out towards the end of the month. A well-prepared site with lots of organic matter dug in is essential. Planting celery in blocks aids the blanching process, as does placing a strip of plastic around the edge of the block to exclude some light and further improve the pale colour and sweetness of the blanched stems.
It is still possible to sow vegetables indoors, especially in colder regions. This will shorten the growing time needed to reach maturity and harvest. Young plants can be planted out once conditions are suitable.
Sweetcorn works best sown in blocks, at 45cm (18in) spacing, with two seeds per hole. The strongest seedling can be selected later, and you will have the safety of knowing there is a fall-back in case of one seedling being devoured by slugs (link to advice) or similar.
Leeks can either be sown in rows outside in a traditional seedbed, or indoors (earlier) in modular trays, with five or six seeds per module. Either way, they need transplanting when they reach about 10cm (4in) in height. A large dibber (or old spade handle) is used to make holes (about 7.5cm/3in deep) for individual plants in their final positions. Drop each leek into a hole, and then fill the holes with water. For module-grown leeks, each cluster is transplanted as one unit, the hole then being filled with water in the same way.
Witloof chicory can be sown this month, to have some ready for forcing next winter (when other salads can be scarce). Sow in drills directly outside.
Runner beans benefit from well-prepared ground with lots of well-rotted manure and organic matter dug in. They need to be planted alongside suitable supports (often a frame or wigwam of bamboo canes tied together with twine) for the shoots to twine around and grow upwards.
Earth up potatoes (unless planted through black plastic) when the shoots are 23cm (9in) high, in order to prevent the new tubers going green. Earthing-up is the drawing up of soil around the stems of the plants, leaving just 5cm (2in) of shoot uncovered so that the plant has enough foliage to continue growing. You can also grow potatoes in containers.
Start to remove sideshoots from cordon tomatoes that were started off early under cover. The sideshoots develop in the leaf axils (i.e. between the stem and leaf), and if allowed to develop will sap the energy of the plant and reduce the quality of the yield. Sideshoots can be pulled off with a thumb and forefinger. It is now too late to sow new tomatoes, as they will not have time to ripen over our British summer.
Thin out sowings of Florence fennel made last month. The final spacing should be 20cm (8in), with 45cm (18in) between each row.
Strings stretched along the tops of broad bean plants can support them, and prevent them ‘flopping’ once pods develop.
Peas need staking with pea sticks, netting, or pruned twigs from the garden.
Control weeds to prevent them competing for moisture and nutrients. Hoe regularly between rows on hot days to make sure the weeds dry up and die without re-rooting. Weedkiller is usually inappropriate as there is a high risk of it killing or damaging your crops as well as killing the weeds.
Pest & disease watch
Keep an eye out for asparagus beetles, which are black, red and yellow, and their cremy black larvae. Pick them off by hand.
Watch for the small holes flea beetles make on brassica seedlings. Water plants well to help them continue growing despite the pest damage.
Pinch out the tips of broad beans once they start to flower. This helps to discourage blackfly, which otherwise can decimate tender new growth.
Pests can be kept off a wide range of crops, carrot fly on carrots being a good example, by covering them with a fine woven plastic mesh like Enviromesh. Just make sure that the corners are tucked in or buried to prevent them breaching this defence.
Pick yellowing leaves off brassicas promptly, to prevent spread of grey mould and brassica downy mildew. Do not compost such material, but put it in the rubbish, burn it, or bury it deeper than 60cm (24in) depth.
Damping off of seedlings can be a problem with sowings both outside and in modules or containers. Clean equipment and, where necessary, use of fungicides (e.g. Bio Cheshunt Compound) can help to control this problem.
Ensure that crops remaining in the ground, new sowings under cloches, and any stored vegetables, are well protected from mice.
Slugs pose a threat, and slug controls are necessary now, as always.
Pigeons are serious pests of brassicas and other vegetables. Cloches, frames of netting or fleece, and metal cages will help to keep them away from vulnerable crops.
Herbs
Enjoy continual supplies of crops such as basil, coriander and parsley by sowing a little seed of each every fortnight, a technique known as successional sowing.
Sow borage and nasturtium seed for their edible flowers, which can be harvested from mid-summer onwards.
Lift and divide potentially invasive herbs (such as mint and lemon balm) that have outgrown their allotted space. Make sure to remove all stray roots, as they can easily become invasive. Growing it in pots will eliminate this risk.
Control weeds by hoeing between garden plants and by hand-weeding containers. Weed infested clumps may need lifting to disentangle weeds from the plant roots.
Flower garden
Divide clumps of herbaceous perennials that you want to propagate, those that have outgrown their allotted space, and those that are flowering poorly or have lost their shape. Bamboos and clumps of bulbs or rhizomes can be divided in the same way. Just make sure that the transplanted divisions have roots, shoots, and are given adequate water to settle into their new positions.
Cutting back clumps of spring-flowering perennials such as Pulmonaria and Doronicum can encourage a fresh flush of foliage, which is more attractive than old, mildew-covered stems. The plants will also remain more compact and flower better next year.
Divide Primula (primroses) after flowering, planting them in a nursery bed until they are ready for planting out again in the autumn, for a display the following spring.
Divide hostas as they come into growth.
Spreading and trailing plants such as the annual Lobularia (sweet alyssum), and the perennials Alyssum and Aubrieta, can become tatty and patchy. Trimming them back after flowering encourages fresh growth and new flowers.
Deadhead tulips and daffodils.
Apply a liquid fertiliser to spring bulbs after they have flowered, to encourage good flowering next year, and help prevent daffodil blindness.
Allow the foliage of daffodils and other spring-flowering bulbs to die down naturally rather than tying in knots. Only remove it or mow it once it has turned brown and floppy.
Lift and divide over crowded clumps of daffodils after they have flowered.
Lift clumps of forget-me-not once the display wanes, and before too many seeds are released. They can become invasive if left unchecked.
Put supports in place for herbaceous plants before they are too tall, or for those - like peonies - that produce heavy blooms. Adding rigid supports afterwards usually looks unattractive and results in bunched stems lacking sufficient ventilation. Criss-crossing strings from hidden or decorative posts work well, allowing stems to grow up in the gaps between strings.
Harden off plants raised from seed and cuttings by leaving them outside for gradually increasing periods of time. Start with only the warmest part of the day, and build up to overnight exposure. Doing this for 10-14 days before planting them outdoors permanently (whenever the risk of frost has passed), will reduce any check to their growth while establishing in their final position.
Plant out cannas and dahlias when danger of frost is past.
Thin out direct sowings of hardy annuals. This is best done in two or three stages at fortnightly intervals. Final spacing should be between 10-20cm (4-8in), using the upper limit for tall or spreading plants, and the lower limit for smaller plants. Prick out indoor sowings when they are large enough to handle without damage.
Sweet peas need training and tying in to their supports to encourage them to climb and make a good display.
Pinch out the leading shoots on plants such as Chrysanthemum and Helianthus to encourage bushy plants. However, if tall thin sprays are preferred, they can be left un-pinched, perhaps removing a few buds (known as ‘disbudding’) to encourage larger blooms.
Liquid feed plants in containers every two to four weeks.
Keep tubs, hanging baskets and alpine troughs well watered. Use collected rainwater, or recycled grey water wherever possible.
Remove faded wallflowers and spring bedding from beds and containers, to make space for summer plantings.
Tubs can be planted up with summer bedding in milder areas. In cold areas, it is advised to wait until well into June, or until all risk of frost has passed. You can always keep some horticultural fleece handy to cover pots in the event of a cold night being forecast.
If you want to grow your own spring bedding for next year, many common choices (including wallflowers, pansies, and Bellis perennis) need to be sown between now and July in order to flower next spring, as they are biennials (which live for two years, and flower only in the second year, as opposed to annuals, which live and flower for one year only).
Winter bedding plants for the following winter can also be sown from now until July. Attractive choices include ornamental cabbages, kales and winter pansies.
Take softwood cuttings of tender perennials like Argyranthemum, Pelargonium and Fuchsia. They will provide new plants for display later this summer.
Perennials that are showing new shoots from the crown can be propagated via basal stem cuttings. Shoots 8-10cm (3-4in) high are cut from the parent plant with a sharp knife. Sometimes a piece of root can be taken with the cutting (which speeds establishment), but stems can be cut without root, and then dipped in hormone rooting powder before striking into growing medium, as for softwood cuttings (see above).
Pot on plants showing signs of being root bound. You can tip out the root balls of unhappy looking containerised specimens, to see if they are indeed pot bound or if they are suffering from some other problem.
Hoe borders to prevent annual and perennial weeds from spreading and seeding themselves.
When gardening on wet soils work from a long plank of wood rather than treading on the bed to avoid compacting the soil.
Pest & disease watch
Inspect lilies for the scarlet lily beetle as the larvae can strip plants in days.
Vine weevil larvae can be a serious pest of containerised plants, and become active this month. Tip out the rootball of suspect plants, and inspect for the creamy, orange-headed maggots, which tend to curl up into a ‘C’ shape. There are various chemical and biological controls available.
Aphids can multiply rapidly during mild spells. Remove early infestations by hand to prevent the problem getting out of hand. Protect sweet pea plants in particular, as they can get sweet pea viruses, which are transmitted by aphids and other sap-sucking insects.
Continue to protect lily, delphinium, hosta and other susceptible plants from slugs and snails.
Remove dead leaves from around the basal rosettes of alpine plants to prevent rotting.
Top dress spring-flowering alpines with grit or gravel to show off the plants and help prevent rotting around the neck.
Glasshouse, conservatory and houseplants
Apply shade paint to the outside of the glass or use blinds on sunny days to prevent temperatures from soaring.
Open doors and vent on greenhouses to increase ventilation on warm, sunny days.
Damp down the floor of the glasshouse regularly on hot days, to increase humidity levels. This benefits plant growth and also reduces the risk of pest problems such as glasshouse red spider mite.
Don’t forget to give glasshouse plants more space as they put on new growth. This will help to prevent disease, and to contain early pest infestations.
Harden off your half-hardy bedding plants that were started off early under cover. By placing them outside for a short period only, at the warmest time of day, and then gradually increasing the length of time they are outside, you can avoid the ‘shock’ that they otherwise experience when moved outside suddenly and permanently.
Check plants at least every few days, to see if they need watering. Seedlings will need daily attention. Use rain, grey or recycled water wherever possible.
Continue to prick out and pot on new seedlings and cuttings.
Try growing on plug plants in your glasshouse. They are a relatively cheap source of large numbers of plants, and avoid the need for propagation facilities and time-consuming pricking out.
Move conservatory plants, such as Cymbidium, Ficus and Citrus outdoors during warm days but bring back inside if cold nights are expected.
Clean shiny-leaved plants with a damp cloth and spiky plants with a soft brush.
Pot up houseplants showing signs of being rootbound or top dress large containers with fresh compost.
Hydrangeas and fuchsias can be propagated from softwood stem tip cuttings.
Pot on any Begonia, Gloxinia and Achimenes plants that you started off earlier in smaller pots, but which are now large enough to re-pot in the next size up.
Cool conditions and regular watering will help keep potted indoor azaleas looking good for longer. Remember to water azaleas with rainwater collected in a rain butt, not with tap water.
Train the new stems of passionflowers over frames or on horizontal wires.
Pest & disease watch
Regularly inspect plants, and also the structures of the greenhouse and conservatory, for glasshouse red spider mite, whitefly, thrips and other pests. Careful attention to the undersides of the leaves, and to each plant in turn, can spot early infestations that would otherwise be missed. Control with approved treatments, and hang yellow sticky traps to help monitor numbers of flying pests.
Damp down the floor of the glasshouse regularly on hot days, to reduce the risk of glasshouse red spider mite.
Damping off of seedlings can be a problem with sowings under glass. Clean equipment and, where necessary, use of fungicides such as Bio Cheshunt Compound can help to control this problem.
Brush up fallen compost and debris, and pick off dead leaves from plants. This will help prevent pests and disease spreading.
Trees, shrubs, roses, climbers and hedges
Cut back tender shrubs such as Penstemon, Caryopteris and hardy Fuchsia after danger of frosts has past.
Clip evergreen hedges. If not too woody, shredded clippings can be added to the compost heap.
Prune spring-flowering shrubs such as Berberis, Chaenomeles, Choisya and Ribes after flowering. Remove one stem in three from Kerria and Spiraea ‘Arguta’, and shorten the other flowered stems to a suitable sideshoot. Evergreens such as Viburnum tinus can also still be trimmed this month.
Prune overcrowded, dead or diseased stems of Clematis montana once it has finished flowering. Untangling the stems can be fiddly, but once you can see where you are cutting, you need not worry about pruning this plant - it will take even hard cutting back very well.
Late spring is a good time to coppice or pollard Eucalyptus.
Prune out frost damage from affected evergreen shrubs.
Young mimosa trees (Acacia dealbata) can also be cut back now. Mature trees respond less well to pruning.
Remove any reverted green shoots on hardy variegated evergreens, to prevent reversion taking over.
Prune wall-trained pyracanthas, removing any shoots coming out from the wall, and shortening other new growth to about 8cm (3in). This encourages spur formation, and increased flowering relative to green growth.
Tie in climbing and rambling roses as near to horizontal as possible. This will restrict sap flow causing more side-shoots to grow along the length of stem. Therefore more flowers will be produced.
Twining climbers (such as honeysuckle and Clematis) need regular tying in and twining around their supports.
Ensure newly planted trees and shrubs do not dry out. Water with rain, grey or recycled water wherever possible.
Loosen any tree ties that are digging into the bark, or could do so soon as the trunk girth expands.
Take softwood cuttings of deciduous shrubs, including Forsythia, Fuchsia, Hydrangea macrophylla, Philadelphus and Spiraea.
Layering is a good way to propagate climbers and lax-stemmed shrubs. Layers should root by next spring, especially if attention to watering is given during dry weather. Examples to try include Philadelphus, Forsythia, Hydrangea and Lonicera.
Pest & disease watch
Viburnum beetle grubs start nibbling holes in the leaves this month, giving plants a tattered appearance. Inspect V. tinus and V. opulus regularly and spray or pick off the grubs by hand.
Check roses for signs of blackspot, aphids and leaf-rolling sawfly damage.
Inspect sick looking box and holly trees for signs of blight.
Phytophthora root rots can cause die back on mature trees and shrubs. Wet winter weather followed by a hot spring and summer can encourage this problem on susceptible woody plants.
Caterpillars, aphids and other fly pests can all be problematic at this time of year. Early infestations can be managed by hand removal, but approved insecticides are necessary for more serious attacks.
Check for damage or cankers on deciduous trees.
Camellias sometimes fail to perform as well as hoped. This can be down to insufficient watering in the previous summer or current spring, but can be also be due to problems with frost, wind, or poor soil conditions. Try improving cultural conditions before concluding that the problem is a pest, fungus, or virus.
Lawns and meadows
Cut the lawn edges with a half-moon edging iron to ensure they are neat and well shaped.
Use the half-moon edging iron, or a spade, to create a 7.5cm (3in) gutter around the lawn edge. This will prevent grass from creeping into the border from the main lawn.
Add grass clippings to the compost heap in thin layers (too much grass all at once is likely to be very wet and poorly aerated, resulting in smelly slime rather than compost).
Apply a high nitrogen summer lawn fertiliser to encourage a healthy-looking lawn.
Sowing new lawns or over-seeding dead patches can still be carried out in early May. Prepare the ground for sowing, by cultivating, levelling and lightly firming beforehand.
Do not walk over or mow newly sown grass until it has reached a height of 5-7.5cm (2-3in), and then only give it a light trim at the highest setting.
Ensure new lawns (either from turf or seed) do not dry out during dry spells. Keep off them for as long as possible to allow establishment. Don't worry over a flush of weed seedlings in newly seeded turf. These will disappear once regular mowing begins. Lawns from seed should be lightly rolled when the grass is 5-7.5cm (2-3in) high, then give a high cut a few days later. Lower the height of cut gradually.
Lawn troubleshooter
During periods of prolonged dry weather and certainly in areas where hosepipe bans are likely, you could help by keeping your lawn a little longer than usual, and even investing in a mulching mower. Mulching mowers shred the grass clippings very finely and then blow them into the lower layers of the turf, where they act like mulch to help the lawn retain moisture. Because the clippings are fine, the end result is not unsightly, especially later in the season when the lawn gets very dry, and the mulch helps to keep it green rather than brown.
If moss is a problem, choose a combined fertiliser and mosskiller when feeding the lawn.
Selective lawn weedkillers will kill the weeds but not the grass or any naturalised bulbs. However, be warned - they will kill wild flowers growing in the turf.
Disperse dry worm casts with a hard-bristled broom or besom.
Molehills are often a problem in spring, as the creature tunnels in search of food. Traps are the most effective way to deal with this problem.
Ponds
Divide and plant waterlilies if not done last month.
Continue to plant up bog gardens.
Tidy up plants in the bog garden, and mulch with composted bark or garden compost.
Thin out, cut back or divide excessive new growth on aquatic plants.
If not done last month, feed large aquatic plants by inserting slow-release fertiliser tablets well below soil level around the base of the plant. Waterlilies are big feeders.
Keep ponds and water features topped up.
Clean out pond filters.
You can still plant new aquatic plants this month. Plant vigorous specimens in aquatic plant baskets to contain them. Top the surface with a layer of gravel to prevent the fish from stirring up the compost.
Small plants in baskets can be raised up on bricks when first introduced then slowly lowered to the bottom of the pond as they increase in size.
Begin stocking ponds with fish once new plantings have established. Avoid introducing goldfish to wildlife ponds. They will eat frogspawn and so upset the natural balance.
Fish will need feeding. Little and often is best, to prevent excess food leading to unwanted algal blooms.
Pond troubleshooter
Remove blanket weed by twirling around a rough stick. Skim off floating weeds such as duckweed with a net. Leave weeds on the pond side for 24 hours to allow trapped creatures to return to the water before adding to the compost heap.
Grille coverings (either simple meshes or bespoke features) can protect young children from accidents. The size of the mesh can be judged in order to prevent hazard, but to also allow access for wildlife, and to preserve the aesthetic appeal of the pond.
Monitor the water level of your pond, as defects in liners and concrete structures may have developed and need repairing.
New or recently cleaned ponds can suffer problems with algae. Providing some shade can help reduce this problem. Ironically a covering of Lemna (duckweed) can provide sufficient shade to help suppress the algae until cultivated aquatic plants establish sufficiently to suppress the duckweeed’s proliferation. Other helpful measures include filling the pond with rainwater rather than with tap water, avoiding contamination of the pond with soil or compost (as these encourage algal growth), and taking care to remove plant debris from the water promptly.
Wildlife gardening
Jobs for the month
- Put out nesting boxes for migrant birds arriving in the UK
- Take care not to disturb nesting birds in garden shrubs and hedges
- Top up bird feeders and put out food on the ground and bird tables
- Avoid chunky foods that could choke young fledglings
- Keep the bird bath topped up
- Regularly clean out the bird bath and table
- Make a log, twig and/or rock pile to create shelter for wildlife
- Put up a bat nesting box
- Put out food for hedgehogs and badgersChoose annuals and perennials to attract insects
- Make the pond more wildlife friendly
- Leave informal hedges un-trimmed for a while to provide food and shelter for wildlife
- Leave nesting birds undisturbed in garden shrubs and hedges
- You can still use plug plants to plant a wildflower meadow
- Mow recently established perennial meadows (but not annual cornfield meadows)
Birds
Don’t let bird flu fears stop you from enjoying the bird life in your garden. You can watch the behaviour of garden birds without coming into any physical contact with them, and as long as you wear gloves, an apron or overall, and a paper face-mask while performing such tasks as re-filling the bird feeder, scrubbing the bird bath, or attending to domestic flocks, you will be keeping the risk at such a low level as to be negligible. Obviously, if you live within a high-risk area where the H5N1 strain of bird flu has been found, or in a restricted zone as designated by DEFRA, then you should take extra precautions as advised (please see www.defra.gov.uk/animalh/diseases/notifiable/disease/ai/).
Most gardens will be in view of nesting birds within nearby hedges and dense trees. Native birds commonly spotted like this include blackbirds, dunnocks, sparrows, thrushes, greenfinches and bullfinches. Wrens, tits and robins can be seen pecking for food at the base of the hedge.
Migrant summer-visiting birds from other continents are among those now common in British gardens. You may see willow or garden warblers, housemartins, swifts and swallows. There are special nest boxes available for swifts and housemartins, but swallows will nest on any suitable ledge or shelf in a quiet outbuilding.
The spotted flycatcher can often be persuaded to nest in a homemade tray, hung on a bracket in a safe spot on your garden boundary, camouflaged by climbing plants. You can then watch the flycatcher from your back door or window as it perches waiting and then flutters up to catch a fly.
If you are lucky, you may hear a cuckoo. These birds have a habit of laying their eggs in other native birds’ nests.
The song thrush may be heard singing at dawn. Although it is a shy bird, you might see it out hunting for snails, bashing them against rocks to crack open the shells. Once its clutch of eggs hatches, it will return to its more usual shy retiring behaviour.
Avoid peanuts and large chunks when putting out food for the birds, as there is a risk that large pieces could be fed by adults to their fledglings, and this could result in choking. Safe foods include wildbird seed mixes (but not those containing peanuts or dog biscuit); black sunflower seeds (the birds will remove the outside casing, and the inner seed is soft); mild grated cheese; sultanas, raisins and currants (best soaked overnight); pinhead oatmeal; apples, pears and other soft fresh fruit; mealworms and waxworms. Alternatively, you can buy fat balls from many garden centres and bird food suppliers. This is an easy alternative, and you can be confident that you will be doing no harm.
To maximise the numbers of different bird species that you attract to your garden, it is a good idea to cater to their different feeding habits. Hanging bird feeders attract species such as tits, finches and sparrows. There are many models available, designed to help keep out rats, cats, pigeons and squirrels, or to fit onto walls, windows, windowsills and balconies. Bird tables attract robins, house and tree sparrows, doves, pigeons, bullfinches, greenfinches, chaffinches and bramblings. Food scattered on the ground attracts blackbirds, thrushes, dunnocks and wrens.
Hanging bird feeders are best sited over a paved or decked area, which can be regularly swept clear of debris. This may help to reduce problems with squirrels and vermin, if they prove a nuisance.
Bird tables are best sited a few feet clear of cover or high vegetation, so that cats and other predators cannot launch themselves onto unsuspecting feeding birds. They can be quite close to the window or patio, as many birds seem to get used to human activity, and are unlikely to be put off by coincidental human activity.
A birdbath can be a vital source of drinking water for birds. Ensure that yours is kept topped up. Models are available to attach to windows, walls and sills, if you are limited for space. Do be aware of hygiene: change the water regularly and scrub the bath out with a mild detergent (available from bird food suppliers) to help prevent the spread of disease.
Insects
Bug life is thriving this month, and should be encouraged. Without insects and other invertebrates, there would be no birds and mammals, and many flowers would fail to pollinate, set seed or produce fruit. Bugs help to keep eachothers’ populations in check, avoiding large build-ups of unchecked pests.
You might notice ants clustered around primulas (primroses), where they are attracted to the waxy coating on the seeds. Bees are common now that the weather is warmer. You may see large iridescent dragonflies (and their smaller cousins the damselfly) swooping around the garden pond. Pond skaters and also water boatmen can be seen skating on the pond surface in search of food. Water boatmen will even dive down into the water in search of a meal - perhaps a tadpole.
Gardens with some nooks and crannies, and a few areas where debris is allowed to accumulate (perhaps a woodland area or a meadow within a more formal design), are often more insect-friendly than those composed entirely of paving, pots, lawn and bedding displays.
Bee homes are now widely available. Initial reports suggest that nesting boxes for colony-forming bees (such as bumble and honey bees) are not always effective, but homes for solitary bees (such as mason bees), made from tubes and tunnels in boxes, are more successful. They are also attractive. Models with a backing are more successful than those open at both ends. This kind of bee house is easy to make at home. Even a tin can filled with straws will do the job. South-facing positions, hanging at chest height or above, are best. Bees usually colonise these homes in spring, hibernating over winter to emerge the following spring. The boxes can be left out over winter, or taken down and stored in a safe place to avoid bees being eaten by predators.
Put out log and twig piles made from old prunings and felled trees. These provide valuable shelter for wildlife, and can be made into attractive features by planting up with ferns, primroses, or other suitable plants. A site well away from the house should ensure that unwanted creepy crawlies do not stray into domestic rooms.
Piles of slabs or rockery stones will act as a suitable wildlife habitat, as will old bales of straw, hay or prunings.
Corrugated iron or plastic laid on the soil can provide ‘tunnel’ hiding places for small reptiles and mammals looking for shelter and warmth.
Mammals
Many garden mammals have given birth to young, and you may spot baby wood mice, shrews or voles, and even fox or badger cubs (most likely in the evenings).
Bats start breeding this month, often in eaves, or behind the weatherboarding of south-facing buildings. Why not put up a bat box on a sunny wall? Many bat species are garden-friendly, eating the midges and tiny insects that cause annoyance on summer evenings.
Hedgehogs are very active this month, looking for mates and foraging for food at night. Hedgehog and badger food is now available for sale. It is not a good idea to feed hedgehogs with bread and milk, as this is not their natural diet. Good quality cat or dog food, or raw minced meat mixed with a raw egg make good alternatives. Do also take care to be sensible with slug pellets, and don’t use more than is necessary. Use wildlife-friendly brands to avoid any risk to hedgehogs and other garden animals.
Plants for wildlife
As a very general rule, single flowers attract more insects than double blooms. Bear in mind that insects can be attracted to a particular plant for its nectar (Sedum spectabile), its pollen (Lavatera species), the shelter it provides (many ornamental grasses and other species) or its suitability for breeding (many native trees, shrubs, climbers, or weeds, such as the common nettle). A variety of insect-friendly planting fulfilling all these needs is likely to attract many more insects than is a mass planting of a single species fulfilling only one.
Hedges, even non-natives and conifer hedges, are a very good resource for wildlife, providing shelter, nesting sites and food for wildlife. Deciduous trees, particularly natives like oak, or coppiced hazel, are excellent for wildlife. Some insects that happily feed from a variety of plants are more selective about their breeding territory, and show a preference for native plants. Deciduous trees also support so much more plant life underneath their canopy, with bulbs, annuals and perennials thriving in their dappled shade. This is not the case underneath dense coniferous planting.
Be less frequent with your hedge trimming to provide greater shelter and food for insects and birds. Don’t trim any hedge that has birds nesting in it. You can get the growth under control once the fledglings have flown the nest and it is left abandoned.
You may wish to identify a suitable part of the garden to leave untouched as a wildlife area. A small patch behind a shed is perfectly fine if you’re worried about it looking untidy.
Although it is now too late to sow a wildflower meadow, you could still plant one using plug plants that have been grown on a little in the greenhouse, or outside. Spray a weedkiller containing glyphosate on patches of the existing grass. Plant the plug plants into the bare patches once the grass has died. This will only work where the existing grass is not very vigorous. Ryegrasses can overwhelm meadow flowers. If you do have ryegrass, another option is to over-seed with yellow rattle. This is an annual parasitic plant that can be sown directly on to grass, gradually weakening it, and hopefully self-seeding from year to year, producing pretty yellow flowers.
Recently sown perennial meadows should be mown about six to eight weeks after sowing, when they reach a height of 5-10cm (2-4in), and then again every couple of months in their first year, removing the cuttings each time. This helps to control weeds and to toughen up the meadow plants. A stronger healthier meadow will be the end result.
Recently sown annual wildflowers do not need mowing. Just leave them to develop and flower, but be aware that will only last one year, and will die back completely in the autumn.
Garden structures
Use a stiff-bristled brush or pressure washer to remove algae from paths. A proprietary algae killer may help.
Remove dirt and algae from walls, paving and patios. Pressure washers can be rented if necessary.
Check and repair pergolas, arbours and arches if needed.
In dry spells, you can treat timber structures with wood preservative and stain. Only do this in a well-ventilated space, to reduce the risks to your lungs and eyes. Make sure you use appropriate products. Creosote, for example, is no longer legal (link to page on products taken off the market).
Go through your shed and remove any old, out-of-date garden chemicals. If in doubt of how to dispose of them, your local authority tip should be able to help. You can check our list of chemicals removed from the market for up-to-date information.
Gardening for children
As well as being able to take part in many of the above activities, here are some extras especially for them.
Get children to harvest cut-and-come-again salad leaves, as these can simply be plucked carefully from the base of the plant. Children can also dig up matured radishes and beetroot.
Sowing many vegetables and ornamental plants can continue this month, a task that children generally enjoy. See the main gardener’s calendar (above) for details of suitable plants to sow this month.
Set children to gather twigs for use as natural-looking stakes, perfect for peas and some garden flowers. Make sure they don't poke themselves - especially in the eyes.
Herb plants need checking for mouldy or yellowing leaves, and bedding plants need regular deadheading – these ‘picking over’ tasks develop children’s concentration and give immediate results in improved plant appearance, for which the children can be rewarded and take pride in their work.
Children enjoy playing with water and garden hoses, and can be tasked with feeding bedding plants, containers and perennials with a liquid feeder attached to the end of a hose (as sold by several companies). This is fun on a warm day, as well as being an important garden task, especially when gardening on thin soils. Teach them the value of water and correct watering and not to waste this precious commodity.