One year’s seeds seven year’s weeds
This little seedling of the Norway maple (Acer platanoides) is one of the small forest that germinates in my garden each spring. The maples are a constant reminder of the old chestnut (as in: saying) in the title.
Why would you get seven years of weeds from one year of seeds? One reason is that it’s a form of plant birth control.
Perennial plants live and reproduce for many years.
Therefore, to varying degrees, their seeds are genetically programmed not to germinate all at once. By having some seeds lie dormant for a few years, the species spreads the fruits of one year’s fertility over many. This ensures its survival should future seasons be less hospitable for reproduction.
Think about it; if every year, every single seed produced a fertile plant that lived for many years (each year, producing many seeds, every one of which produced a fertile plant, and so on), the species would overpopulate.
This prudence doesn’t only apply to weeds – remembering that “a weed” can simply be any plant growing in the wrong place.
If you like a flower, for example, but it self-seeds too abundantly, a solution is simple: don’t let it go to seed.
Deadhead the plant after blooming, before the seeds ripen. Some of the colonizing spring bulbs (such as the Scilla or Chionodoxa we posted about earlier) might fall into this category if you find them becoming a pest in your garden.
Or, if you’re disappointed when trying to start flowers from seed, be patient. Some seeds just take longer.
Others have to be helped along by techniques such as pre-soaking or by nicking the seed coat. The seed packet will recommend your best strategy for this. Don’t skip that step.
By the same token, if you’ve been weeding: don’t add ripe weed seeds to your compost pile, unless your pile gets hot enough to kill them.
Back to the Norway maple. It produces a truckload of viable seeds, meaning seeds that will sprout. (As an aside, the lovely native sugar maple, A. saccharum, is very stingy with its own – which has helped the Norways run rampant through our naturalized ravines.)
I can’t do anything about deadheading trees, and don’t have room to create a nice hot compost pile. Plus, my yearly mulch of uncomposted maple leaves will always contain seeds.
So I’ve developed another kind of patience, and learned to accept the seedlings. Pulling them up has become a perennial rite of spring. As I do, I fortify myself with this mantra: One year’s seeds…
One year’s seed is seven years’ weed
Who wants to spend hours bent double doing a job that will only need to be repeated in a matter of weeks? Well me, for one. Thanks to my strict Wisley training I find it difficult to concentrate on the greater picture when I know that there’s weeding to be done.
You could argue that a weed is only a plant in the wrong place. In New Zealand, lupin, gorse, cobaea and ginger, all of which are colonising native habitats, are treated as weeds by local gardeners, while in Britain we have a growing list of notifiable weeds that were originally introduced as garden ornamentals. Heracleum mentagazzianum, the giant hemlock, is using waterways to float its boat-shaped seed to pastures new. Japanese Knotweed is pushing up tarmac and buddleia, once introduced as an exotic ornamental, is now part of our industrial landscape. Indeed, it loves the urban jungle so much that it turned the bombsites purple after the Blitz.
My childhood friend Geraldine had a garden that was, by some standards, full of weeds. Her bearded iris battled it out with wild oats and scarlet pimpernel. She would part a tussock of grass to show me her thriving Fritillaria pyrenaica and the raspberries always came with a sting from the nettles. The truth is, she knew where her plants were and what they needed to survive the competition from these weeds: the pimpernel was a happy accident, the nettles food for the butterflies. It is all a question of interpretation.
My definition of a weed is a plant that does not fit in with the chosen scheme because – given a chance – it will overwhelm everything else. Brambles were not welcome in my London garden because there was simply not enough room for them and they took two years to clear, but in a country setting I would not want to be without a patch to pick in the autumn. Now that the garden is cultivated, the enthusiastic self-seeder Verbena bonariensis is potentially the greatest problem I have.
There is also the question of balance. The yarrow took over a newly established meadow that I sowed in a garden on the South Downs. It loved the thin alkaline soil and outgrew its companions in the first two years. The client was all for digging it out – hours of backbreaking work – but he was persuaded to leave well alone and, in year three, the slower-to-establish perennials and wild grasses caught up and crowded the yarrow out.
So a weed is a plant that competes for food, water and light, and will check the growth of anything more demure. Even a young tree will be at risk until it has established a large enough root system to supply it with sufficient water and nutrients. Keep a yard diameter clear at the base for the first three years and it will literally put on twice the growth of a plant left to fend for itself.
The great secret is to start with ground that is free of all perennial weeds. Couch, equisetum, ground elder, dock, bindweed and creeping thistle are just a few of the worst offenders and I would prefer to see ground left bare for a year to rid it of any of these than to plant a pending disaster.
To clear the ground you have several options. I am all for the organic approach if you have time. Forking over the soil to get the bulk of the roots out is worthwhile but every little piece left behind will be a potential cutting, so the process may need to be repeated several times and left for a month to six weeks in the growing season to make sure there is no regrowth.
Putting in potatoes is a good idea. Planting and cropping offer opportunities to turn the soil and most annual weeds will be smothered by the vigorous potato foliage. The reward for all your effort will be in the eating.
Opaque mulches are another alternative which can be very successful. A layer of black plastic or several layers of cardboard laid over the ground will kill most perennial weeds in a growing season. Some weeds, however, are more persistent than others – in one garden I was astonished to find bindweed writhing around after a full year of mulch. This was the same plant that went 7ft deep in the clay bank we excavated. That would require some digging out, so we resorted to Glyphosate. The safest of all the systemic weed killers, this is rendered inert when it comes into contact with the soil and works best when applied to foliage that is in full growth.
Only this spring, I was forced to delay a client’s planting because a new garden that had been prepared over the winter came back with flushes of couch and thistle in April. I was intending to plant most of the garden with ornamental grasses, but weeds among the ornamentals spells complete disaster. Once entangled, they are impossible to separate. We had thought the autumn spraying of Glyphosate would be sufficient, but hadn’t bargained for the slowdown in autumnal growth.
Weed seed in the ground presents a less serious problem. Once you’ve dealt with the perennial bullies, seedlings and annual weeds will be the main issue. These need to be pulled before they seed or get a hold, as one year’s seed is very definitely seven years’ weed. It is best to do this little and often, parting all foliage to find those lurking in the shadows. Hoeing is a great way to work through your beds on a sunny day if the ground has not been mulched – if it has, you would not want to disturb the mulch and reduce its weed smothering properties. A final reworking over the same space immediately after you have finished will always reveal a straggler or two just waiting for your back to be turned.