Fast growing flowers: quick perennials to grow from seed

We asked four experts to choose their favourite herbaceous perennials to grow from seed, which will flower in their first year – offering quick but beautiful, budget-friendly blooms for your garden.

By Veronica Peerless

Published: Tuesday, 07 March 2023 at 12:00 am

With perennials often costing £10 and upwards at the garden centre, it makes sense to grow your own from seed. Sown in early spring, many perennials will flower in their first year, and will come back every year, making them excellent value.

We asked four experts – Derry Watkins, owner of Special Plants in Wiltshire, Xa Tollemache, garden designer, Joseph Atkin, head gardener at Aberglasney Gardens in Camarthenshire and Marina Christopher, nurserywoman and skilled propagator, to recommend their favourite fast perennials to grow from seed.

How to grow perennials from seed

Most hardy perennials can be sown in early spring, under cover in modules or seed trays at a constant temperature of around 18-20°C – a heated propagator helps to ensure a steady temperature.
Once the seedlings have germinated (this can take anything from a couple of weeks to a couple of months, depending on the plant), remove them from the propagator and place on a sunny windowsill or in a greenhouse.
Once they have produced true leaves, prick them out.
As they grow, pot the seedlings on into larger pots.
Harden off before planting out in late spring or early summer.
Alternatively, you could scatter the seed where you want it to grow in late summer or autumn, when most plants are naturally producing seed.

Fast growing flowers from seed: quick perennials to grow

Scabiosa atropurpurea ‘Black Knight’

© Jason Ingram

Spectacular, big, near-black flowers speckled with tiny white stamens. A tall plant, usually grown as a cut flower, this will need some support and a few friends around it to hide its rather unattractive legs. Height: 90cm. RHS H4.
Recommended by Derry Watkins

Pennisetum thunbergii ‘Red Buttons’

© Jason Ingram

The red-flushed flowerheads of this grass bob above compact green foliage from late summer through autumn, gradually bleaching to buff. It prefers a sheltered position in full sun, and is quite drought tolerant once established. Height: 80cm. RHS H3.
Recommended by Derry Watkins

Read our Pennisetum growing guide.

Sidalcea ‘Rosaly’

© Getty Images

Grow this for its pale-pink, wide-open, mallow-like flowers, which are arranged in spires on upright stems, and will bloom on until the first frosts if deadheaded. Very showy and loved by bees. Height: 90cm
Recommended by Derry Watkins

Antirrhinum majus ‘Sonnet White’

One of the selections from the Sonnet Series, ‘Sonnet White’ offers upright stems crammed with those familiar-looking snapdragon flowers in pure white. Often grown as an annual, the Sonnet Series can also be grown as a short-lived perennial. It’s a great cut flower and loved by bees, as well as being easy to grow from seed. Sow February to April. Height: 45cm. RHS H3, USDA 7a-10b.
Recommended by Xa Tollemache

Cephalaria gigantea

I love this at the back of a border, floating about and attracting bees – and such an exciting plant to have grown from seed. Scabious-like flowers in cream with a tinge of yellow are held high on long stems. Another great choice for pollinators and as a cut flower. Sow in March for summer flowers. Height: 1.8m. RHS H7, USDA 3a-7b.
Recommended by Xa Tollemache

Delphinium Belladonna Group

There are various cultivars in this group, offering choices in pink, white, blue and purple. It’s the brilliant blues that I really love. Tall stems with racemes of delicate- looking flowers make great impact in border and are perfect for cutting. Sow indoors in spring. Height: 1m. RHS H4, USDA 4a-8a.
Recommended by Xa Tollemache

Achillea ptarmica ‘The Pearl’

This is a charming little border plant, growing quickly to form a mound. It can be invasive but don’t let that deter you from growing what is sometimes described as
a perennial gypsophilia, with its sprays of white double or semi-double button flowers. Cut back after flowering for a second flush. Sow indoors February to June. Height: 75cm. RHS H7, USDA 3a-9b.
Recommended by Xa Tollemache