Q&A - Weeds

Q. I have recently sown grass seed that started to grow very well, it is about 2-3" high, but all of a sudden bindweed has taken over the whole of the garden. I've looked for a feed and weed type product but they all state the lawn has to be at least 6 months old. Is there anything I can do?

A. Even if your lawn was older most of the lawn weedkillers would not be effective on bindweed. If you are very careful you can paint Roundup GC (glyphosate) onto the leaves of the bindweed. It is a slow job but very effective. It may take 3 weeks to see results and the best time to apply this is when the bindweed is actively growing in the spring, summer and autumn. To stop the weedkiller dribbling or washing onto your lawn you could put pieces of old carpet under the leaves that you paint with the RoundupGC. You only need to paint several leaves per stem and there is a gel available which will be easier to use. You may need a couple of applications at 3 week intervals for a complete kill.

Q. I have lots of Lesser Celandine in my garden. How can I get rid of it?

A. Lesser Celandine just loves damp conditions. Because it grows from tubers it is quite difficult to get rid of. It also seems to seed very freely. One of the best ways for the longer term to keep it at bay is to improve the soil conditions so it is not so damp. Try adding lots of well-rotted manure or compost and coarse grit to the worst areas and mulching with a layer of 5-7.5cm (2-3") of well-rotted manure or compost after you have dug out all the celandine that you can see. You can also spray with Roundup GC which contains glyphosate but do take care not to get any on your other plants. Otherwise just keep pulling out every bit of celandine as soon as it appears and eventually most will disappear.

Q. Could you please advise me on how to eradicate clover from my flowerbeds? In spite of vigorous and regular weeding, it continues to spread.

A. Clover can usually be eradicated by regular weeding but some of the roots may be deep which is why you are having problems. The other method is to use a chemical control such as RoundupGC. The best time to apply this is in the spring to autumn when the weeds are actively growing. You will need to take care not to get the chemical on other plants as it will kill these too but does not affect the soil in any way. If you are applying Roundup to the clover between your border plants I would suggest you buy the gel formulation, which is brushed onto the cloverleaves. It usually takes 3-4 weeks to take full effect and sometimes several applications are necessary but I have usually been successful first time.

Q. I wonder if you can tell me the most effective method of killing Japanese Knotweed? It is now becoming too invasive and taking over and choking other plants and bushes in the garden?

A. Japanese knotweed is a very invasive weed as you have found and is difficult to control. You need to persevere with it for several years in order to eradicate it. Try digging up as much as you can now and then as soon as new growth appears next spring spray it with brushwood killer or Roundup. You will need to do this several times each time new growth appears. Take care that the spray does not go onto other plants. If it is growing amongst other plants you may have to dig these out and get rid of them entirely. You need to be fairly brutal in order to get rid of the weed and may need to wait a year or two before you replant.