Gardening: Biennials to plug the gap between spring and summer
Plant biennials to plug the gap between your spring and summer displays, says Adrienne Wild
For a rich tapestry effect, mingle
different-coloured varieties of wallflowers among a batch of tulips
Forward planning is the key to creating a great-looking garden and, without realising it, you may already be well practised at doing this, especially if you are planting springflowering bulbs now with the aim of producing a show to lift you out of the winter gloom.
You may also be familiar with sowing frost-tender or half-hardy annuals, such as cosmos, marigolds and tobacco plants in the warmth early in the year, to provide colourful patio displays in summer. But you may have noticed that there is a gap that desperately needs to be filled between the two seasons. This can easily be done and for little expense with some less-demanding seedraised plants like wallflowers, blue or white forget-me-nots, scented stocks and honesty.
These plants are biennials and usually come into their own in May, offering some of the best flowers at this time of year. To cultivate your own plants, though, seeds should have been sown in a sunny corner of the vegetable plot in midsummer – timing is everything when forward planning!
The seeds should be sown in an out-of-the-way spot and will quietly germinate and grow without flowering in the first year then, in autumn, can be transplanted to where you want them to flower. In their new positions, they will remain dormant over winter, then have another burst of growth before flowering in spring and early summer.
If, however, you missed this important time slot for sowing, you’ll find that garden centres are now stocked to the hilt with spring-flowering biennials ready to be planted along with your favourite spring bulbs.
Honey-scented wallflowers (Cheiranthus cheiri or Erysimum cheiri) are one of the most popular biennials but, as they are members of the brassica family, are also subject to clubroot, flea beetle and attack by the cabbage white butterfly, so it’s important not to line out the young plants where cabbages have grown the previous year. Covering the plants-in-waiting with Enviromesh netting will afford them some protection.
When buying wallflowers during September and October, you’ll find that they are mostly sold in bundles of bare-rooted plants in mixed colours. For best results, look for freshly dug supplies and make sure they have some soil attached to strong, healthy roots. Single-coloured named varieties are also available but, more often than not, they are sold in pots and usually in spring, when they can
Sweet rocket Wallflower ‘Vulcan’ Stocks make a beautiful scented gap-filler