What are weeds? The generally accepted definition is that a weed is merely a plant growing in the wrong place. Like the little petunia in an onion patch. Now is the time of year that the plants which the majority of us would agree are weeds start to grow at a rate of knots. Which leaves us all with one big problem. How does one control them? It all depends on what the weed is and where it is growing.
Take the lawn, for instance. The lawn is where you will find the low growing weeds - the sort of weeds that can withstand close and regular mowing - daisies, dandelions and speedwell. And yarrow, which normally grows quite tall, but when in a lawn learns to keep its head down. If your lawn is fairly free of weeds, and those that you do have are spread out, you could use a touch-weeder. This is a sort of waxy block which you rub on to the leaves of the weeds, which then start to grow like there is no tomorrow, and then give up the ghost and die. However, if you are not that lucky you will have to resort to a selective weedkiller, either with or without a fertilizer dressing. The straight weedkillers usually come as liquids which you dilute before applying, whereas the combined weedkiller and fertilizer dressing generally come as granules and which you spread over the lawn. Now is a good time to do it. For granules it is best to use a wheeled distributor, or a weedkiller which comes with a dispenser, to apply the stuff evenly. Read the instructions on the packet to find when to use it and when to water after you have used it. Most lawn weeds will give up the ghost when treated in this way, and the grass will then grow to fill in the gaps, thanks to the fertilizer content. Those weeds which are not obliging enough to fade away straight away may need another application. But there are some weeds - speedwell for instance - which are harder to bump off. Try dusting it lightly (and the operative word is 'lightly') with sulphate of ammonia. This is high in nitrogen and will make the grass grow. Speedwell is not too keen on it and will probably decide that it is not going to hang around if it is going to be treated like that.
Beds and borders that are fairly weed-free can be kept that way relatively easy. Provided there is room, annual weeds such as groundsel and chickweed, are easily removed with a hoe, but remember to use the tool as a cutting instrument, not a digging one. The object is to separate the top growth from the roots so that the two parts die without each other's support. Perennial weeds will have to be hand weeded. And once the border is free of weeds it can be kept that way by mulching. Not only does this save a lot of time and effort later on but it also makes the plants grow better. Do it when the soil is moist. Sprinkle a little fertilizer on the soil and then cover it with a 2in. or 3in. layer of organic matter. Chipped bark (longer lasting than pulverised bark), garden compost or very well-rotted manure can all be used. If you use manure make sure it is really well rotted. Otherwise you might find your borders coming up buttercups and daisies come the summer.
There are weedkillers which contain glyphosate. These will kill any plant that they touch, so you must use them carefully. Use them as a spray on a still warm day so that they don't get blown by the breeze on to every other plant in the garden. If it starts to get too close to your beloved roses or azaleas or what-have you, cover them with plastic while you wield the sprayer. It will kill ground elder and convolvulus (though two or three applications may be necessary) as well as less persistent weeds. It is the best bet when you need total kill on ground that has not yet been cultivated because it is absorbed by the plants and has no effect on the soil. Do not expect instant results. It will be a few days before you see the weeds turning yellow. Eventually they will go brown, and die.
But what about ground elder and convolvulus in beds and borders? In this position, they are extremely difficult to eradicate. You can paint on a glyphosate-based weedkiller, which will be taken down to the roots, but this is tedious in the extreme on a large border. You could also train convolvulus up canes instead of your plants. Then, when they have reached a reasonable size, remove the cane and roll up the bindweed carefully so as not to break the stems. Then put it into a plastic bag and spray them. In this way, only the bindweed gets it in the neck.
Getting rid of perennial weeds in a large planted border is a long job. The only way, really, is to dig out all the plants and remove the weed roots from among them before replanting them in rows on the vegetable plot or some spare ground. Then dig out all the weed roots you can find. Now leave it so that all the roots that you didn't find can grow and show themselves. Treat the empty border two or three times during the season with glyphosate until it is clean. But don't forget to check the plants regularly during the summer months to make sure that no weeds remain entangled with them, and then they can be replanted in the cleaned-up border come autumn or spring. But don't be too eager to destroy every weed in sight. The roots of horsetail - and marestail contain minute quantities of gold. Grow enough of them and you could get rich, providing the cost of extracting the gold doesn't turn you into a pauper.
And one last piece of information. There is now an easy way of controlling couch grass in borders. There is a weed killer which will kill the grass without damaging broad-leafed plants. Now there's a thought; perhaps one day we'll have more weed killers which are specific to certain plants without killing anything else. That really would be a step forward. Until then, just keep mulching.
Happy Gardening.
written by Bill Hutchings
Bill Hutchings welcomes any suggestions for gardening subjects that you might like him to write about in this Column. You can contact Bill via our Feedback email, or let the Editor know.
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