The seedier side of gardening

There’s nothing I like better than a spot of horticultural retail therapy, which often involves ordering from the seed catalogues far more than I could reasonably hope to raise in a year. But Autumn, and harvest time, bring with them the chance to gather seed for ourselves, and while this may be a little more hit-and-miss than buying from the commercial suppliers, it’s an activity for which our gardening lives are all the richer.

From high summer onwards, the garden borders have been stuffed with plants eager to fling their seed about with promiscuous abandon. And, if there’s one thing a gardener loves, it’s a free plant, particularly when sourced from someone else’s garden1.

The better to make the most of these opportunities, I’ve stuffed a wad of small, manilla envelopes into my trusty old school Filofax, which accompanies me everywhere. In the absence of an envelope, a paper bag would do, but it would have to be brown, by virtue of there being advanced to date no satisfactory explanation for the existence of a paper bag that is anything other than brown. Were the contents of the bag to be, say, a quarter of flying saucers, chocolate limes or aniseed balls, a white paper bag, or a striped paper bag, might do – at a push – but it would be stretching the bounds of common decency. The main point is to be prepared, because your pocket, or purse, is no suitable receptacle for a handful of seedheads, there to be blended into an unholy potpourri from which nothing recognisable shall ever be extracted.

Collecting seed: Malva moschata f. alba

Collecting seed: Malva moschata f. alba

Collecting seed: Malva moschata f. alba

Some of our garden lovelies need little help from us – those prodigious self-seeders we love to encourage, in the certain knowledge of reliable drifts of colour the following year, which only require from us a little tailoring or sculpting by the application of a judicious spot of seedling pulling or relocation. Such plants usually have tiny seeds, and lots of them – foxgloves and poppies spring immediately to mind – though something like Verbena bonariensis, with its slightly larger seed, is just as prolific. Once the seeds are dried out and rattling in their capsules, you may be tempted to cut off the long stems and skip merrily through the garden, waving the crinkly wands about after the manner of a crazed Morris Dancer, but while such audience participation isn’t strictly necessary, it can be handy to scatter seed in areas you’ve felt may have looked a bit empty this year. In the dappled shade around trees with the foxgloves is a favourite.

Hollyhocks – biennials, like the common foxglove Digitalis purpurea – are happy to get on with things. Needing no mollycoddling from us, at least in the early stages when rust fungus is unlikely to trouble them, seedling plants do seem to migrate towards the front of a bed, and the flow of your planting may benefit from having these tall plants moved towards the back. Hollyhocks have long tap roots, so transplanted seedlings will need to be moved with care and watered in well whilst establishing in their new location. If growing from seed under cover, the seeds will benefit from a soaking overnight to soften the tough seed case prior to germination.

Collecting seed: Hollyhock Alcea rosea

Collecting seed: Hollyhock Alcea rosea

The expression “going to seed” has negative connotations – perhaps it’s not hard to see why. The production of seed is the culmination of a flowering plant’s season, and annuals in particular will have exhausted most of their resources in order to produce the seed from which the next generation will grow, leaving tired looking stems and foliage. Perennials have a bit more stamina, and many will remain a stately presence in the border throughout the winter, holding on to their seed heads for as long as the gardener can control the urge to deadhead everything in sight. Echinacea is one such plant, as is Phlomis russeliana, whose tiered flower stems turn from yellow-green to rich brown towards the end of summer. One twitter pal recently told me how she likes to watch her hens comically tweaking the seedheads to shake out the tasty contents.

Phlomis russeliana around pollination time...

...and a few months later, Phlomis russeliana seedheads ripe for the harvest.

...and a few months later, Phlomis russeliana seedheads ripe for the harvest.

In truth, there’s no limit to the seed you can collect – providing you beat the hens to it. If it’s brown and seedy, give it a go, with the hope of free plants, and the knowledge that if nothing comes of it, you’ll have invested nothing more than a modicum of time, a dash of compost and a little water. A few points, however, will help to make your seedy activities go with a swing. 

Collecting seed: Lychnis coronaria

Most seeds should be collected when just ripe - wait too long, and they'll start to disperse. If the seeds are still green and fleshy, leave them on the plant. If they're brown, black and rattling, they're good to go. If they're dropping all over the ground, they'll be fine, but collecting them will be more of a job!

  1. Try to collect seed in the middle of a dry day, when the morning dew has burnt off and before the damp of the evening falls. Moisture is the enemy of seed collectors, encouraging either germination, which you don’t want till you’re ready, or rot, which you don’t want at all. If you have to collect when the plants are slightly damp, lay them out on a sunny potting bench or in the airing cupboard as soon as possible to dry out.
  2. Place the seedheads, cut with a little stem for ease of handling, head first into an envelope or paper bag, into which the seeds can be shaken when completely dry.
  3. Be aware that some large seeds – notably from big trees such as oak, magnolia, or walnut – need to be kept moist at all times. In these cases only sealable plastic bags are preferable for harvesting.
  4. As soon as is practicable, extract the seed from the chaff – all extraneous parts of flower, capsule, stem that you may have gathered when harvesting. These decompose quickly and will encourage the presence of moulds that can damage the seeds themselves or linger to weaken the emerging seedling upon germination. Assemble a mini toolkit for the process – eyebrow tweezers and tea strainers can come in handy!
  5. Keep the seeds in the fridge until needed in order to reduce their metabolic rate – this will preserve them for longer. A sealable glass jar with a desiccant  is ideal.
Collecting seed: Astrantia major

Collecting seed: Astrantia major

Collecting seed: Astrantia major

Are you a big seed collector, or is it something you’re minded to give a go this autumn? Let me know on twitter @darwinboerne, or in the comments below. 

1With, of course, the express permission of the owner. [looks a bit shifty]