Germination and determination

Spring is an anxious time in the seed frame, interspersed with small moments of triumph.

One area where forest gardening is definitely trickier than annual agriculture is in raising plants from seed. Annual crops have been bred not to hang about when it comes to germinating; mostly they just need a little warmth and a little moisture and off they go. The seeds of perennials are often more cautious creatures; they want to be sure that the time is just right before they will consider coming out to play and they may have very exacting requirements that must be met before they do.

Most simply, many seeds need a period of cold (known as ‘stratification’) before they will then respond to heat by germinating. You can see their logic: they want to be sure that they are germinating in spring and not in autumn. Some take it further and need a period of warmth, then cold, then warmth again. Some are even more complicated, virtually guaranteeing that the gardener will panic and leave them in the one place where they will definitely never germinate: in the packet.

I can’t say I’ve ever really, properly got the hang of growing perennial seeds. Mostly I sow them in pots or seed trays in a greenhouse in time for them to experience a winter’s cold, with mixed results. Last year was a bit of a disaster. I spent lots of money on seeds from the Agroforestry Research Trust and put them in poly bags with damp sand in the fridge, as many books will tell you to, for the amount of time specified for each species. In April I took them out and spread the sand on top of compost in seed trays in the greenhouse. Very little grew.

I think the problem may have been the seeds rotting in the sand and possibly drying out in the compost. This year I have taken a different approach, putting them right from the start in a container where they could grow happily, which will seal up and retain moisture and which converts instantly to a seed tray with built in water tray. This miracle of technology is called a margarine tub.

First I drill some holes in the bottom of the tub, to allow water to drain out. I almost fill it with a good peat-free compost (using rubbishy, cheap compost has cost me a lot of seeds in the past I think, as it dries out so easily), sow the seeds and then cover them with vermiculite and/or sand depending on how big they are. Then the lid goes on and they go in the fridge. Ones which need some heat first have the lid put underneath as a water tray and go in a heated propagator or on the window sill. I’m also giving up on the greenhouse in favour of a more gentle spring heat on the windowsills.

So far the results have been promising. Only a few have actually germinated so far, but you would expect that and all the seeds look healthy and vital.

In the past I have found out that record keeping is as big an issue with seeds as the kit that you use. I’m not one of nature’s record-keepers and I’ve already managed to lose track of which of my seed potatoes are earlies and which are maincrop as I mysteriously forgot to note which varieties were which when I set them up for chitting. The useful thing about the margarine tubs is the ease with which you can write on them. I write each a label but also write the name on the tub. When they go in the fridge, each tub gets its release date written on the front in large digits.

Where the stratification requirements of a seed would leave it germinating half way through the summer I am leaving it in the packet for the time being. These are generally the ones which would naturally drop their seeds around August and then experience late summer warmth, winter cold and spring warmth. If they don’t get the autumn warmth they go into quite deep dormancy and this is the state that you get a lot of tree seeds in from seed companies. The simplest thing seems to be just to wait for their natural seed fall time to come round again and put them in their tubs at that point.

Seeds that have sprouted so far with me this year include Japanese and cherry plums, Crataegus succulenta (an edible hawthorn, with a very promising Latin name I think!), Allium sphaerocephalon (round-headed leek), Chaerophyllum bulbosum (turnip-rooted chervil) and Asclepias incarnata (swamp milkweed).

Leave a Reply