Collecting seeds: harvesting later-flowering seeds

Collecting Seeds: Harvesting Later-Flowering Seeds

In this lesson, I'm going to share a range of collection methods that I use for popular seeds that ripen later in the year.

Seeds you might collect later in the year – often September – include cosmos, dahlias, zinnias, marigolds and hollyhocks. The hollyhocks I don't sow myself as they self-sow so readily, but I like to be able to give seed away.

Collecting Hollyhock Seed

• The seeds start maturing from the bottom of the stem upwards – may still be flowers at the top.
• Snip off a 'button' of seeds from the base and open it up to release the seeds.
• Seeds can be sown now, direct or undercover in greenhouse, or stored.
• If you sow now the plants may flower next year, whereas in spring they'll take another year.

Collecting Dahlia Seed

• Single-flowered dahlias produce hundreds of seeds from a single head and every seed is genetically different.
• Species dahlias such as Dahlia merckii and Dahlia australis may come true or may have cross-pollinated.
• Ensure seedhead is completely dry or pick and leave to dry in greenhouse in a paper bag
• Seeds are around a central cone.
• Gently tease open the seedhead over a tray and seeds will start dropping out.
• Separate out any feathery seed casing to leave the long black seeds. The drier they are, the easier they will separate.

Collecting Zinnia Seed

• I've been saving seed from my pastel shades mix from Marlston Farmgirl; sowing the saved seeds has produced some lovely pastel shades and also bright orange 'reversions'.
• Zinnia seedheads are a bit more robust than dahlias.
• Break up the central cone to release hundreds of seeds.

Collecting Cosmos Seed

A friend said seed saved from cosmos 'Purity' had come up beautifully so I'm giving it a go.

• A bit like a dahlia seedhead – very delicate.
• Gently break it apart and feathery seed casings will come off.
• Pick or gently blow these off to leave the long black seeds.

Collecting Marigold Seed

• Not just one of the easiest flowers to grow from seed but also one of the easiest to collect.
• Large, curved seeds are easy to take off the seedhead.
• Since they're hardy annuals, I sow a few straight away in autumn undercover to plant out early and get earlier flowering than those I sow in spring.

Why Collect Seed?

Collecting seed is another rewarding part of growing from seed that completes the circle of life.

• It's another way to engage with your garden and plants and observe them closely.
• The more you watch and observe the more plants you'll find to collect seed from – I'd never tried harvesting cosmos seed until this year.
• It's all about experimenting and seeing what you can do.

While I'll always buy seed, as some things don't come true and I love trying new varieties each year, saving seed is another way to save money and is really environmentally friendly.

"It makes you really look at the seed and seedhead and marvel at how it's been formed"

Plant Directory

Alcea rosea

Hollyhock

Herbaceous hardy perennial

Malvaceae

Calendula officinalis

Common marigold

Hardy annual or biennial

Asteraceae

Cosmos bipinnatus 'Purity'

Mexican aster 'Purity'

Half-hardy annual

Asteraceae

Dahlia australis

Southern dahlia

Tuberous half-hardy perennial

Asteraceae

Dahlia merckii

Merck dahlia

Tuberous half-hardy perennial

Asteraceae

Zinnia MFG (Almost) Perfectly Pastel (mixed)

Common zinnia MFG (Almost) Perfectly Pastel (mixed)

Half-hardy annual

Asteraceae