Advice
RHS Help & Advice
Growing hardy annuals
Direct your thoughts to sowing direct. Hardy annuals can be excellent value for money and need not be fiddly or labour intensive to grow - sow them in situ and a single packet of seed is often enough to fill a small bed with a summer full of colour.
Hardy annuals can be sown straight into the soil because they are generally not affected by frost. Seed catalogues often use the abbreviation ‘HA’ to describe them.
Annuals do best on light soils that are not overly fertile. Sow when the soil begins to warm (often indicated by the emergence of weed seedlings). Weed the bed, level the soil with a rake and tread lightly before sowing.
Sowing
One method of sowing is to cast the seed evenly over the soil surface and cover with a thin layer of soil. However, it can be difficult to identify the annuals from weed seedlings, making weeding difficult or impossible. So a better method is to sow in drills, using the depth recommended on the seed packet. Water the bottom of the drill then sow thinly, spacing the rows 30-45cm (12-18in) apart. The seedlings will need thinning a couple of times before their final growing distance is reached.
Colour blast or pastel shades?
Raise a smile with the jolly court jesters Ismelia carinata (syn. Chrysanthemum carinatum) or yellow and white Limnanthes douglasii (poached egg flower). Look forward to summer sunshine with Eschscholzia (California poppies), now available in a whole spectrum of colours such as red and yellow ‘Strawberry Fields’ or the varying pinks of ‘Champagne and Roses’. The large seeds of Tropaeolum majus (nasturtiums) are particularly easy to sow and, again, a wide range of colours is available.
For a more delicate colour scheme, consider white or pink Crepis rubra (hawk’s beard), the pink shades of Silene armeria or pretty Iberis umbellata ‘Fairy’ - a mixed-colour selection of candytuft.
Good for wildlife
As well as being ornamental, some annuals provide nectar and pollen for bees, hoverflies, butterflies and other insects. Phacelia tanacetifolia, Calendula officinalis, Agrostemma githago, cornflowers and sunflowers are all suitable.
There is no need to worry about deadheading if you plant annuals with attractive seedheads or seed pods; these can also be valuable food sources for birds and other wildlife. The sumptuous red or green tassels of Amaranthus caudatus (love-lies-bleeding), the inflated seedpods of Nigella damascena (love-in-a-mist) and many Papaver (poppies) remain attractive long after the flowers have faded.
A little bit different
Pale pink Linanthus grandiflorus (mountain phlox) is lovely coupled with Cosmos and Lavatera trimestris (annual mallow). For the front of borders, sow diminutive Linanthus androsaceus, reaching only 10-15cm (4-6in) high.
Nemophila is known for its ‘baby blue eye’ flowers, but N. menziesii ‘Pennie Black’ has white-edged, black-eyed blooms. The bright pink, purple or white bracts of Salvia viridis are definitely eye-catching, and for talking points try Moluccella laevis (bells of Ireland) for its spires of stiff, green, bell-like flowers.
At the end of the season
Enjoy your annual border for as long as it looks good. Deadheading will prolong some flowers, but pull out plants and compost them as they go over. On lighter soils, you may find self-sown seedlings. These can either be hoed, making room for winter bedding, or left to flower next year. Thin seedlings and transplant the surplus to fill gaps elsewhere in the garden.
Helen Bostock
Sowing hardy annuals in autumn