Save seed from your garden now for free plants next year

In September the garden is brimming with seeds – poppies, eryngiums, geraniums, lunarias, sanguisorbas, salvias, corydalis, sanguisorbas, gillenias and most of the grasses. Everything is there, just waiting to be harvested.

This seed is probably better quality than any seed you will ever buy, because it is fresh, and fresh seed virtually always germinates better than old seed. Growing a plant from seed you have collected yourself is incredibly satisfying – you come to know and love that plant in a very intimate way.

Collecting seeds in metal bowl — For the easiest seed, such as poppies, foxgloves and kniphofias, I just tip the stems into the bowl so the seed falls out. If seedpods rattle but are not open yet, I collect the whole pods – some will pop open later, some I will have to crack open. Many seeds are attached loosely to the seedhead and will fall into my bowl if brushed gently. I try to collect as few leaves and stems and bits of pod as possible. When you come to sow your seed, you don’t want any extraneous plant material or chaff with it. The seed is clean, but other plant material might pass on diseases and encourage rot in the seedlings. ©Jason Ingram

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Not everything will come true from seed. Most named cultivars are hybrids and won’t. But if you have only one variety of a species in your garden, then it should come fairly true. Different species in the same genus generally won’t cross. And even if the seed does not come true, it may still be delightful.

Seed bags drying — As soon as I have collected one type of seed, I write its name on a paper bag and tip the seed in. I fold up the bag and store it in my basket before moving on to the next. When I’m finished, I peg all the seeds to a clothesline in an upstairs room in my house, where there is plenty of ventilation, to dry for a few weeks.©Jason Ingram

If you buy a packet of seed and you sow it directly into the garden, you know that most of it may be eaten by mice, birds or slugs. When you collect your own seed, you can collect plenty and be generous in sowing it, scattering handfuls. And if you store it, you can be sure of storing it correctly so that it will be in the best possible condition for sowing next year.

Keeping your seed dry is crucial to making sure it stays viable for as long as possible

Seed gradually ripens over the summer and you have to keep an eye on your plants to be sure you don’t miss something important. Most seed is only available for a few weeks (some only for a few days) before it drops. A few will be ready in May or June, but the great flood of seed comes between August and October. I go out on regular seed patrols every few days to find which seed is fully ripe and ready to collect.

Woman sorting seeds at table — When the seeds are totally dry, I clean them. One at a time, I empty the bags into a big bowl and look for the seed. Usually it is obvious which is the seed and which is the chaff, but occasionally it can be hard to distinguish. First, I find a sieve a bit bigger than the seed so the seed will drop through and all the bigger bits of chaff can be thrown out. Then I use a sieve that is a bit smaller, so you can sieve all the smaller bits out. ©Jason Ingram

The best seed will always be that which is ripe. When seedpods begin go ‘crack’, or you can hear the seed rattling in its pod, you know the plant has put its all into the seed and is now ready to send it off into the world. If you have to tug the seed off the plant, it is probably not ripe. Gently brushing the seedhead with your hand should be enough to make the seed fall.

Woman blowing on seeds — Once I have sieved out as much chaff as possible, I find a shallow bowl, tip the seed in and shake it gently. For some miraculous reason chaff is virtually always lighter than seed and will work its way to the top. Then, just like the farmer winnowing his wheat, I blow gently across the bowl (not directly into it) as I shake it. And wonder of wonders, the chaff blows out as I shake. ©Jason Ingram

By the time it is ripe, most seed will have changed from green or white to grey, brown or black; and it should be hard. If you can get your fingernail into the seed, it is not ripe. If at all possible, wait until you know the seed is fully ripe before collecting. You will get better germination and the seed will last longer. When you’re ready to collect, choose a dry sunny day, so the seed is as dry as possible.

Woman sorting seeds — When there is no chaff left, I pour the seed into a paper envelope (a funnel can help here) and label it with the name and date. ©Jason Ingram

What you'll need to collect seed

I take a few bowls, a lot of paper bags and a pen in my basket. You’ll also need at least one sieve. I have a large collection to minimise the amount of time I have to spend winnowing (separating seed from the chaff), but even one sieve is usually a big help.

Seeds in evelopes — I store all my seed envelopes in an airtight box with some silica gel to make sure they stay completely dry. About once a year, I dry the silica out for an hour or two in a slow oven in case it has absorbed too much moisture from the air every time I open the seed box. Keeping your seed dry is crucial to making sure it stays viable for as long as possible. Keeping it cold will help, but is not as critical. I refrigerate any seed that is known to be short-lived, such as anemones, hellebores, all the umbels, fritillaries, pulsatillas, thalictrums and aconitums. ©Jason Ingram

8 easy seeds to collect in September

Seed head — 1 Eryngium giganteum Once the seeds have turned dark-brown they are ripe and ready for picking, and can easily be removed by rubbing the seedhead. Sow immediately or leave to dry for a week before storing. Height and spread: 70cm x 30cm. AGM*. RHS H6, USDA 4a-7b†. ©Jason Ingram

Seeds on plant — 3 Kniphofia rooperi When the heads of this red hot poker turn brown and the little seedpods open, tip them into a bowl so the seeds fall out. 1.2m x 60cm. RHS H7, USDA 4a-8b. ©Jason Ingram

Seed plant — 4 Sanguisorba officinalis Once the claret-red flowerheads are dry and brown, remove the seeds by gently rubbing or shaking them into a bowl. 1.2m x 60cm. RHS H7, USDA 4a-8b. ©Jason Ingram

Plant — 5 Setaria italica ‘Red Jewel’ Gently brushing the seedhead with your hand should be enough to make the seed fall. 90cm x 30cm. ©Jason Ingram

White flower — 7 Corydalis ochroleuca As flowers fade, the seedpods begin to turn yellow. Pull the plant up and cut the top few inches into a bag. A few weeks later, all the seed will have fallen into the bottom of the bag. 60cm x 60cm. RHS H5, USDA 5a-7b. ©Jason Ingram

Useful information

Find a wide selection of Derry’s seeds at her nursery and online shop, Special Plants. Address Special Plants, Greenways Lane, Cold Ashton, Chippenham, Wiltshire SN14 8LA. Tel 01225 891686. Web specialplants.net

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Save seed from your garden now for free plants next year

What you'll need to collect seed

8 easy seeds to collect in September

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