How to grow and enjoy hardy annuals
Hardy annuals give value for money. Some self-sow for 20 years, writes Gerry Daly
The great charm of hardy annuals is that they flower in a great surge of energy over a fairly limited time in summer. They are brilliant summer colour providers. Being informal plants, hardy annuals are not suitable for use in formal flower beds. Their tendency to have a single burst of flower rules them out for containers, too, because they have a limited season.
Their main use in gardens now is as colourful fillers-in, ideal for odd corners and gaps between other plants. They give a cottage-garden look to a bed or border - a jumble of types of different heights and colours flowering over a period in mid-summer.
Hardy annuals are flowers that generally are not affected by frost and so are hardy. They are annuals because they flower and shed seeds on an annual basis, but some stretch to more than one season, though are not robustly perennial.
Hardy annuals are raised from seed sown in seed trays, the young plants being transplanted to their flowering locations, or directly in the ground where the plants are to flower. They can be sown in March, April or May. March sowings can be affected by cold, wet weather. May sowings can be affected by dry conditions and, anyway, they tend to flower late.
April is usually a good time, and slow this year, so there is time. Seeds of some types can be sown in September to over-winter as young plants and flower earlier the following summer than the spring sowings.
Dig the ground, working in some fertiliser and old compost. Break up all lumps and rake the surface fine. Make little drills with a cane about 15cm apart and 1cm deep. Sow the seed thinly and cover lightly with soil. Make the same soil preparations for transplants.
Seed can be sown broadly scattered too, but sowing in lines makes it easier to separate flower seedlings from weeds. Hardy annuals grow best in good, fertile, but not overly rich, soil in full sunshine. Some kinds, such as California poppy and pot marigold, can tolerate quite poor, dry soil.
When the rows of seedlings can be distinguished, lightly run a hoe between them to kill weed seedlings. Weeds should never be allowed to get established. Watch for slugs and snails, too. When the seedlings are about 2-5cm high, a first thinning can be carried out, though, if the seeds were sown thinly enough, this may not be necessary.
When the seedlings are 5cm high, they can be thinned to their final spacing. This varies from 5 to 10cm apart for small kinds to 30cm apart for large types. If there are gaps, they can be filled by lifting and transplanting excess seedlings carefully.
Some of the taller types, such as cornflower or nigella, may flop about when grown on good soil. Bushy twigs might be used for support. Hardy annuals often self-sow and seedlings pop up in all sorts of places. This is never really a big problem to control. Many are good cut-flowers for the house too.
Among those to try are: pot marigold, California poppy, poached egg flower, viper's bugloss, nasturtiums, nigella, cornflowers, candytuft, night-scented stock, nemophila, sweet peas, godetia, lavatera, larkspur, Shirley poppies and ammi, among others. It is inexpensive and even one packet of seeds can produce a fine display.
Some kinds need special attention, such as sweet pea that climbs and need support of cane wigwams or the like, and nasturtium that spreads and needs space, but most are easily managed and just get on with it, as long as they get off to a good start with thinning and weed control as suggested. A single sowing of California poppy has been known to self-sow for over 20 years.
SPRING IN YOUR STEP: Forest bathing is all the rage, but a walk in greenery is rejuvenating too. Why not take a guided tour amidst the splendid spring blossoms and foliage of the National Botanic Gardens, Dublin? Monday-Saturday, 11.30am and 3pm. €5 each. Sunday, 12pm and 2.30pm, free entry.
PLANT IT: Cherry trees have been slow to flower this spring and some are weeks behind but one kind has been truly outstanding, namely a variety called Prunus 'Okame'. It has produced a tremendous display of dark-pink flowers on bare ascending branches. It is not as big as some cherry trees and fits in smaller gardens.
AND THE WINNER IS... Congrats to Mayo's Céide Fields which is the winner of this year's International Carlo Scarpa Prize for Gardens, organised by Fondazione Benetton Studi Ricerche, and dedicated to a place "particularly rich in natural, historical and creative values". The area will be photographed and documented in a beautiful book, and form the material for an exhibition in June at the Municipal Theatre, Treviso.