Professional gardening tips No.1 (Growing Annuals from Seed)
01 May 2020
Growing Annuals from Seed:
Written by Clare Foster
Photographs by Sabina Rüber
Growing annuals from seed was always something I'd dabbled with on the side. I might lazily scatter handfuls of poppy or nigella seeds around the garden in the hope that they came up in odd corners, or if I had time, sow a few cosmos or zinnias to boost the late summer display, but that was the extent of my dabbling. Like so many of us, I had been hooked on laissez faire perennials for so long that I'd almost disregarded the value of annuals, dismissing them as too time-consuming.
So it was with some trepidation that, with photographer Sabina Ruber, I embarked on an experiment to grow as many annuals as possible in one season. We were not to know that we had picked the worst year ever for growing annuals, with three months of solid rain from April to June, low light levels, late frosts and high winds, all of which would challenge even the most experienced of growers. But it is possible to learn as much from disasters as from success, and I reached the end of the season with a real appreciation of how annuals can enhance a garden and how they can satisfy the desire to try something new every year (a bit like the feeling you get from buying new clothes each season). Producing substantial, fast-growing plants from seed is incredibly satisfying. The flowering season is long and the colours and flower-types endlessly diverse, and of course it is much cheaper than buying ready-grown plants from a nursery.
Before we started our research we had to confront the definition of the word ‘annual’. A true annual is one that completes its life-cycle in a year - growing from seed, flowering and producing more seed before it dies - but there are many other so-called annuals, like salvias for instance, that are perennials or shrubs in their native habitats but treated as annuals in Britain where the first signs of cold weather kill the plant off. Then there are short-lived perennials, like Verbena bonariensis, which may return as a perennial the following year, but are more likely to self-seed and regenerate that way. And finally come the biennials, which flower in their second year before fading away at the end of the flowering season. All these were included in our selection.
Once we started looking at the seed catalogues, the real eye-opener was that there were so many more species and cultivars available to us than we had realised. There were annual climbers, grasses and meadow flowers; annuals for scent, for cutting and for pots. There were bold and beautiful annuals to make strong statements (cleome or amaranthus for example) and delicate, lacy annuals for filling gaps in the herbaceous border (orlaya and ammi). In addition to the low-growing bedding annuals, there were also tall, exotic beauties like the Mexican sunflower, Tithonia rotundifolia, or the extraordinary fiery-orange Leonotis leonorus, which grows to over 2m tall in one season. There were unusual forms of cottage garden flowers (like the beautiful Nigella papillosa 'African Bride' which offers an alternative to the more commonly grown N. damascena) and old-fashioned favourites such as wallflowers and snapdragons available in tasteful new colours. Like children in a sweet shop, we wanted every single one, and ordered as many as we thought we could realistically handle (which in truth was always going to be too many). Chiltern Seeds, Thompson & Morgan and Sarah Raven were our main sources, with Chiltern Seeds offering the widest range.
Then came the time to start sowing. I divided my seeds into three categories: direct-sowers; hardy annuals to be sown in pots; and half-hardy varieties to be sown indoors and cosseted until after the last frosts. The direct-sowers seemed the easiest - and should have been, had it not been for the weather. I sowed poppies, nigellas, scabious and cornflowers in drills on my allotment in balmy late March. A month later they had all been washed away or rotted by the rain, and in their place grew big, strapping weeds. Usually there is at least another window of opportunity to re-sow in the weeks ahead, but this year the rain was relentless and another opportunity just didn’t arise. It just made me all the more determined to try again next year.
I focused instead on the annuals I had sowed in pots and seed trays, which were now crowding out every available windowsill and the mini-greenhouse. I learnt two important lessons: first, that you really don’t need a whole seed tray full of the same plant, so it is better to sow seeds in smaller 9cm pots which take up less space; and second that it is a cardinal sin to firm the compost down too much when sowing or after pricking out. This excludes air and drainage channels within the compost, which can cause it to become waterlogged, increasing the chances of damping off (a fungal infection of young seedlings), or conversely, dry out too much making it difficult to re-water.
I also learnt that sowing times aren’t set in stone, and can be stretched this way and that. Hardy annuals can be sown either in autumn (to give them a head start and earlier flowering) or spring, while half-hardy annuals can be sown in two or more tranches, like successional vegetable sowing, to prolong the flowering season. I reached this conclusion by default when I hurriedly sowed a new batch of cosmos in mid May after an entire tray of beautiful fat seedlings was reduced to stalks overnight by a snail or slug. The result was that the beautiful semi-double Cosmos ‘Psyche White’ was still flowering profusely in my garden in October.
I discovered that growing annuals is addictive. Admittedly it is time-consuming, the seedlings needing frequent attention, and success rates can vary hugely depending on weather and wildlife, but nothing beats the feeling of seeing those emerald-green seedlings emerging – and then watching them grow and flower, and thinking, ‘I made that’. My year-long annuals experiment doesn’t end here: I will just try and be less ambitious next time and limit my seed-buying spree to a few old favourites… and one or two irresistible new ones.
All these annuals appear in Clare Foster’s book, The Flower Garden; how to grow flowers from seed, published by Laurence King and available on Clare’s website www.budtoseed.co.uk.