Seed capital: How to repopulate your own garden

Many popular hardy annuals are prime candidates for autumn seed-saving

Rich pickings: ripe seed heads of Thalictrum. Photograph: Richard Johnston
Rich pickings: ripe seed heads of Thalictrum. Photograph: Richard Johnston

We’ve all done it, haven’t we? By which I mean making an impromptu decision to tidy up the garden while wearing your best bib-and-tucker. It begins innocently enough. Returning home from a smart event or family gathering, you spot a flower begging for some speedy deadheading, or perhaps a few wind-snapped stems that need to be removed discreetly. The next minute, you are up to your waist in plants, furiously yanking out weeds with one hand while gesturing to your bemused other half to pass you the wheelbarrow.

All of which explains why I spent a couple of hours this week using a tweezers to painstakingly prise the tiny, wiry, barbed seed-heads of the perennial ornamental grass, Stipa tenuissima, out of the sleeves of one of my favourite jackets – hundreds of them, which had to be pulled out one by one. For sheer tedium and mind-numbing repetition, this beats a multitude of other tasks. I’d willingly de-bone a dozen fish fillets or top and tail a bucketful of gooseberries than do it again.

On the plus side, I had to admit to a certain painful irony in the fact that I’d paid good money for seed of this very same grass only months earlier. By the time I’d finished tweezing out that very last stubborn seed, I’d calculated my haul to be worth in the region of several dozen euro. All of it fresh, ripe seed too, unlike the stuff you might get from the less scrupulous seed merchants, which germinates slowly, unevenly, or not at all.

Stipa tenuissima, or Mexican feathergrass, as this floaty, golden ornamental grass is also known, is just one example of the many garden-worthy plants whose seed is ripe for harvesting within the next few weeks. Other ornamental grasses whose seed is similarly suitable for autumn harvesting include its taller, elegant relative, the golden oat grass (Stipa gigantea) and the gorgeously imposing red tussock grass (Chionochloa rubra). Many of the most popular kinds of hardy annuals are also prime candidates for autumn seed saving. Examples include pot marigolds (Calendula), cornflowers (Centaurea cyanus), honeywort (Cerinthe), French marigolds (Tagetes), Love-in-a-mist (Nigella), the Opium poppy (Papaver somniferum) and the white laceflower (Orlaya grandiflora).

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The same goes for many biennials and perennials. Examples include species dahlias, masterwort (Astrantia,), Thalictrum, honesty (Lunaria), sweet William (Dianthus barbatus), the lofty, violet-flowered Verbena bonariensis, and various species of Eryngium. Plenty of shrubby and woody stuff too, like species roses, Acer and Crataegus. And many heritage varieties of vegetables, including broad beans, French beans, runner beans, peas, tomatoes, chillies and peppers, as well as herbs such as dill, parsley and coriander. And all for free. [CROSSHEAD]Home harvesting[/CROSSHEAD] Not only that, home harvesting of seed also comes with the added boon of knowing that you are doing your bit to help preserve biodiversity. Plus, if you are canny about it, you can select for certain traits. For example, every year I save the seed of a wonderfully tall, branching and very long-flowering variety of Tagetes patula with burnt-orange/ red blooms, each with its own central golden boss. Called Tagetes Cinnabar ex. Great Dixter, it’s an outstanding strain of French marigold that the late Christopher Lloyd hand-selected over many years simply by singling out the seed of only the tallest plants growing in his garden at Great Dixter.

There are a few provisos. One is that the seed of modern hybrids – for example, anything with F1 after its varietal name – won’t breed true to type. Similarly, different varieties of a particular genus (for example, the aforementioned Tagetes) will often cross-pollinate if they are grown close to each other, so expect some interesting progeny from the resulting seed. [CROSSHEAD]Properly ripened[/CROSSHEAD] Another is to make sure that the seed you want to harvest is properly ripened, and that you harvest it on a still, dry day into small paper bags or envelopes. Bring along a small nail scissors to cut off the ripe seedheads neatly, and wear gloves as an added precaution to protect against possible allergic reactions.

But timing is everything, so don’t leave it too late to harvest, or else many plants will have already spilled their seed.

Always make sure to label the bag or envelope clearly with the name, date and place harvested. If you are collecting seed from a garden other than your own, ask the permission of the owner.

Finally, bear in mind that nature has devised numerous ingenious ways of packaging seed so that it remains fresh and viable until needed. So while most plants will readily offer up their seeds, others are a little trickier and may need some help (for example, fermentation).

For more detailed information on how best to harvest, prepare and store the seed of different species, visit the following websites:  theseedsite.co.uk and howtosaveseeds.com.

This week in the garden Pick pears If you have a pear tree laden down with fruit, pick it now before it’s attacked by birds or wasps, and bring the pears indoors before placing them somewhere cool and dark, such as a drawer, to finish ripening. Early varieties will fully ripen within a week while later varieties can take a couple of months

Pull weeds It’s been a record year as far as weed growth is concerned, so it’s especially important to take the opportunity this autumn to hoe away weeds if we are blessed with a dry and sunny day. Remember that weeds left in the ground now will set seed and/or continue to make strong growth, creating even worse weed problems for your garden or allotment next year.

Label dahlias If you are growing lots of different dahlias, then it’s worth taking the time now, while they are still in flower, to discreetly label each plant by using a length of fine garden wire to tie the label to the base of the plant. This will make storage, identification and propagation of the different varieties a lot simpler and avoids the possibility of potentially ugly colour clashes in the garden next year.

Dates for your diary

Wednesday, October 5th, 8pm, Howth Yacht Club, “Planning a Small Garden”, a talk by horticulturist Brian Wood of Murphy & Wood Garden Centre on behalf of Howth & Sutton Horticultural Society, admission free to members/€5 to non-members, see hshs.ie Saturday, October 8th, 10am-4pm, Altamont Walled Garden, near Ballon, Co Carlow, “How to Grow Your Own Cut Flowers Seasonally and Sustainably” , a one–day course with garden writer and flower farmer Fionnuala Fallon, €70 including lunch, email sales@altamontplants.com