Move conservatory plants, such as Cymbidium, Yucca, Ficus and Citrus outdoors during warm days but bring in if cold nights are expected.
Pot up houseplants showing signs of being rootbound or topdress large containers with fresh compost.
Pruning and training
Train the new stems of passion flowers and other climbers over frames or on horizontal wires.
In the greenhouse
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.
Try growing on plug plants in your greenhouse. They are a relatively cheap source of large numbers of plants, and can be ordered and grown on quickly if you didn’t get round to sowing seed in good time earlier this season.
Don’t forget to give greenhouse plants more space as they put on new growth. This will help to prevent disease, and to contain early pest infestations.
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.
Harden off half-hardy bedding plants that were started off under cover.
Apply shade paint to the outside of the glass or use blinds on sunny days to prevent temperatures from soaring.
Open doors and vents on greenhouses to increase ventilation on warm, sunny days.
Damp down the floor of the greenhouse 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.
Pest and disease watch
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.
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 insecticides and biological controls, and hang yellow sticky traps to help monitor numbers of flying pests.
Brush up fallen compost and debris, and pick off dead leaves from plants. This will help prevent pests and disease spreading.
Foot and root rots can affect young plants grown from seed and cuttings, especially those grown under glass.
Clean equipment and, where necessary, use of fungicides such as Bio Cheshunt Compound can help to control this problem.