Professional gardening tips No3 (Growing Annuals from Seed - best flowers for a cutting garden)
17 May 2020
Growing flowers for cutting is one of the most rewarding things you can do in the garden.
Written by Clare Foster
Photographs by Sabina Ruber
Annuals are invaluable for the cutting garden, with the advantage that you can try new varieties and colour schemes each year. They can either be grown in dedicated annual beds rather like a vegetable plot, or threaded in among perennial flowers. Either way, if you have enough space it is really worth giving over a piece of ground entirely to cut flowers – a spot at the bottom of the garden perhaps, where you can plant in rows, mix colours up and generally take a more relaxed approach. Most importantly, it should be an area from which you don’t mind plundering flowers – where the plants aren’t crucial to the design of your garden. It may be psychological, but I also think it’s easier picking flowers from plants raised from a cheap packet of seeds rather than from expensive perennials! In planning an annual cut flower patch, make sure you have a mixture of big-colour-blooms and more recessive varieties chosen for foliage or shape. The best are those that last for ages in a vase, but also the ones that produce the most flowers, responding to cutting by producing yet more and more blooms over many long months.
The number one flowery performer in my cutting garden last year was cosmos (Cosmos bipinnatus), which after a slow start was still blooming at the end of October. Grow a mixture of deep pinky-red ‘Rubenza’ (75cm) and snow white ‘Purity’ (90cm) and you’ll have the basis for many a table arrangement. These luscious single blooms last well over a week in water, and with their intense green ferny foliage they need little to accompany them. I also tried and loved the semi-double ‘Psyche White’, which looked exquisite in a jug with Orlaya grandiflora and Alchemilla mollis, and a slightly shorter cosmos called ‘Antiquity’ (50cm) whose flowers open dark red and fade to a bronzy pink. There are lots of other cultivars that can be grown from seed including ‘Seashells’ and ‘Pied Piper’ with their curious quilled petals, and the delicate ‘Daydream’ with palest pink petals darkening in the centre. I remain to be convinced about the new fully double cosmos ‘Double Click’ (available in various colours including ‘Rose Bonbon’), but some will love it. Cosmos is a half-hardy annual and is best sown in 7cm pots or modules in April, to be planted out in late May or early June. When the seedlings reach about 10cm it helps to pinch out the growing tips to encourage bushier growth.
Annual rudbeckias, zinnias and sunflowers also provide colourful, long-lasting blooms. Choose multi-branching sunflowers with smallish blooms in subtle colours that don’t look out of proportion in a vase. Sunflower ‘Italian White’ (up to 1.5m tall) has palest-yellow flowers with chocolate brown centres; ‘Key Lime Pie’ is similar, but with lime-green eyes in the centre of each flower, while ‘Claret’ has velvety dark red flowers. The Mexican sunflower, Tithonia rotundifolia ‘Torch’, is excellent for cutting towards the end of the summer and into autumn, and in a good sunny year extremely floriferous, forming a large mounded bush up to 1.5m tall with dozens of brick-orange flowers. It is half hardy, so shouldn’t be started off too early. Sow in modules at the end of March or beginning of April, and don’t plant out until you are sure all danger of frost has passed.
All the flowers mentioned so far have rounded or daisy-like blooms. Snapdragons and larkspur offer something different – larger, taller spires of flowers that add contrasting shape to an arrangement. Snapdragons (Antirrhinum majus) come in a wide range of – let’s be honest – garish colours. The best varieties for cutting are the tall, willowy types that grow about a metre tall rather than the squat dwarf types, and those in plain, single colours rather than mixtures. A white variety such as ‘Admiral White’ or ‘White Giant’ would be the most versatile, but if this is all too tasteful, try a colour-clash of ‘Orange Wonder’ and ‘Ruby’ to wake the senses. Larkspur (Consolida ajacis) produces flower spikes of a similar height, in colours ranging from dark delphinium-blue through mauve and pink to white. ‘Blue Spire’ is one of the best, with rich, velvety flowers growing to 90cm tall, while ‘Sublime White’ has double flowers on a 1.2m stem, good for drying as well as cutting fresh. Snapdragons should be sown under cover in March or April to be planted out in late May, while larkspur is best sown direct because it doesn’t respond well to root disturbance.
Above are the big players: now for the quieter, none-the-less essential additions to the cut flower garden to provide background texture and foliage in an arrangement. In addition to filler plants such as Ammi majus and Bupleurum rotundifolium, which have already been covered in the February issue, a plant such as Euphorbia oblongata (50-60cm) is invaluable for its lime green flowers lasting for months through summer and into winter if picked regularly. Actually a short-lived perennial, it is best grown as an annual, is easy to propagate both in pots and direct in the ground, and will self seed if happy. Another florist’s favourite is the apple-green Bells of Ireland (Moluccella laevis). Its striking flower spikes, up to 90cm tall, aren’t really flowers at all – the real blooms are tiny, surrounded by hood-like green calyxes. This can be tricky to germinate, but putting the seed in the freezer for a week before sowing can help. Finally, two plants grown for their purple flowers or bracts: honeywort (Cerinthe major ‘Purpurascens’) and clary sage, Salvia viridis ‘Blue’. Clary sage is grown for its deep purple, veined bracts (45cm) that seem to go with almost any other colour in a vase. Seed is best sown in modules in March or April, to be planted out in May, and it flowers from June to October, holding its colour well when dried. Cerinthe is an interesting-looking plant with smoky bruised-purple bracts and nodding flowers, and as its common name suggests it is a magnet for bees and butterflies. It can be tricky to germinate as the seeds have coarse casings, but soaking them overnight before sowing in seed trays or modules will improve the germination rate.
If you grow just 10 of these flower varieties in an area of say 1m by 5m, you will be able to harvest bucketfuls of fresh flowers from June until November – and if it’s too late to sow seed this year, there is still time to buy plug plants from Sarah Raven or pot-grown plants from nurseries or garden centres.
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.