Our garden editor Clare Foster on the best perennials to grow from seed
I used to think growing anything more exotic than a sunflower or marigold from a packet was too difficult. Then I started a project in 2012 with the photographer Sabina Rüber to grow plants from seed and discovered how easy it is to produce a huge range – perennials as well as annuals – and have raised masses of plants that would cost at least £5 each in a nursery. Some perennials may not flower until the second year, but we found plenty that germinate readily and grow quickly enough to flower in the first year: the blooms might not be large then, but subsequently they will return with all guns blazing.
Most hardy perennials can be germinated under cover in modules or seed trays at 18-20°C and moved somewhere cooler once they emerge. As they grow, the seedlings should be potted on and hardened off before being planted out in late spring or early summer. Alternatively, sow direct by scattering the seed onto the soil in late summer or autumn, when the plant would naturally be producing seed.
Top 10 perennials to grow from seed
- Sabina Rüber1/10
Achillea sibiricasubsp. Camschatica ‘Love Parade’
This achillea is different from the ones we are used to seeing, with a looser feel and softer habit. The pale pink flowers float above long stems and narrow, saw-toothed leaves (50-60cm). From Siberia, it is extremely hardy and easy to grow from seed, and also makes a good cut flower. In early spring, sow in modules and cover with a fine sprinkling of compost or vermiculite.
Also try: Achillea millefolium ‘Summer Pastels’. 
Sabina Rüber2/10Digitalis grandiflora
This lovely pale yellow foxglove grows in sun or dappled shade, reaching 60-80cm. While many foxgloves are biennial, this one is truly perennial, returning year after year as well as self-seeding freely. Flowering in early to mid summer, it can be sown in late winter for flowers the same year or in autumn to get a head start for the next year. Sow the tiny seeds thinly on the surface of moist compost in a seed tray but do not cover. When the seedlings are large enough to handle, prick them out carefully, transferring each one to its own 7cm-diameter pot.
Also try: D. ferruginea.
Sabina Rüber3/10Verbascum ‘southern charm’
This lovely verbascum has elegant flower spikes in pastel shades of antique pink, buttermilk and dusky apricot that are excellent for cutting. Reaching up to 120cm, it will bloom from June to August. Sow under cover in September/October or in February/March for flowers in the first year. The seedlings have long tap roots that do not like being disturbed, so sow seeds one or two to a cell in a modular tray or root trainers (for longer roots), covering with a fine layer of compost.
Also try: V. phoeniceum ‘Violetta’ and V. blattaria f. albiflorum.
Sabina Rüber4/10Alcea rosea
Hollyhocks are rewarding to grow from seed, with different colours available individually and in mixes, as both doubles and singles. One of the loveliest is A. rosea ‘Crème de Cassis’, which has beautiful red-wine-stained petals with intricate veining. The Halo Series is also well worth seeking out. In autumn or early spring, germinate the large seeds on damp kitchen paper in a warm room, and plant them in modules once they have sprouted.
Also try: A. ficifolia.
Sabina Rüber5/10Dianthus carthusianorum
This is a fabulous, magenta-pink dianthus perfect for a gravel garden in a dry, sunny spot. From June until September, the dainty flowers emerge from a mound of grassy green leaves on top of wiry stems 40-50cm tall. Sow either in autumn or very early spring, under cover; they can also be sown throughout spring for flowering the following year. Sow the seeds individually on the surface of the compost in a modular seed tray, but do not cover as they need light to germinate.
Also try: D. cruentus, D. pinifolius and D. superbus.
Sabina Rüber6/10Verbena bonariensis
Long-flowering and versatile, this fashionable plant is easy to grow from seed. Its tall swaying sprays of purple flowers provide a haze of colour until late summer, attracting bees and butterflies. Sow seed in early spring for flowers the same year, scattering onto the surface of moist compost and covering with a fine layer of compost.
Also try: V. hastata
Sabina Rüber7/10Dahlia merckii
Dahlias are satisfying to grow from seed but put aside thoughts of huge dinner plates or stylized pompons as seed-grown dahlias are completely different creatures. D. merckii is just one of the species dahlias available to grow from seed, with small lilac-pink single flowers, and is much more delicate than the cultivars (120-170cm). Seed mixes such as D. ‘Bishop’s Children’ and D. variabilis ‘Sunny Reggae’ are good options, too. In early spring, sow onto moist compost in modules and then cover with a fine layer of compost or vermiculite. Dahlias are tender, so plant out after the last frost.
Also try: D. coccinea and D. australis.
Sabina Rüber8/10Echinacea purpurea
Echinacea is a popular prairie-style plant that grows from seed to flower in a single season if sown in late winter. E. purpurea ‘White Swan’ bears large, white blooms on stems up to a metre tall until late summer. Seed mixes such as ‘Lustre Hybrids’ are also available. Sow thinly onto moist compost, pressing the seeds in lightly, without covering, as they need light to germinate.
Also try: E. purpurea ‘Green Twister’ and E. pallida.
Sabina Rüber9/10Agastache anisata
This aromatic, bee-friendly plant is one of several agastache species and varieties that can be grown easily from seed –some in lavender and blue shades, and others in burnt orange. With pale lavender bottle-brush spikes, A. anisata grows to about 90cm and needs full sun and well-drained soil. Sow the seeds on top of moist compost but do not cover, as they need light to germinate.
Also try: A. aurantiaca
Sabina Rüber10/10Salvia nemorosa
Varieties of this perennial sage, such as ‘Caradonna’, are often bought as pot-grown plants, but you can also grow certain colour strains from seed easily. One of my favourites is ‘Rosenwein’, with its spires of pink flowers (60cm). In autumn or early spring, sow the seed onto the surface of moist compost and cover with a fine layer of compost or vermiculite. Grow in full sun in well-drained soil. Also try: S. verticillata.This is an extract from ‘The Flower Garden: How to Grow Flowers from Seed’, by Clare Foster and Sabina Rüber
