As well as fresh ideas and inspiration, the Gardeners' Question Time podcast offers solutions to…
Listen now 43 mins
Join Eric Robson and panelists Anne Swithinbank, Bob Flowerdew and Pippa Greenwood as they visit gardeners in Kirton in Lindsey, Lincolnshire.
Produced by Howard Shannon.
A Somethin' Else Production for BBC Radio 4.
Q: I bought four boxes of dried out, sad looking, cacti at an auction. Some are brown around the base of the plant. Can they be saved?
A: The sample cactus has the potential to come back to life. At this time of the year cacti have been resting anyway so would need to be kept dry, but the brown suggests they were also neglected last summer. From March onwards you can start watering again and you should see it come back to life. However, the brown areas will not disappear.
Q: Bulbs are often described as easy to grow, so why have I had no success with snowdrops? They die off at the end of the year, but never come back again.
A: The snowdrop is not a local British bulb so they prefer a drier climate with quite a hot summer, but total dryness will actually ruin them just as quickly as water-logging. They will grow better on a loamy/sandy soil than on heavy clay.
Q: My children kindly secured a rose with my name, Rosa Frankish, and gave me a hundred of them. About forty are in my garden. They are a yellow floribunda. They flower three times; first time in June it's fantastic, by second flowering in July they have developed black spot and by the third flowering their are no leaves left. I do spray, but how do I stop it getting established?
A: You think about black spot on leaves, but it doesn't just attack the leaves. It can over-winter on stems, so when you are doing early spring pruning it is worth examining the stems for pin-head sized purple/black spots and pruning these out too. Also make sure you clean up fallen leaves as soon as possible.
Q: Our lawn is professionally treated four times a year with fertiliser and when necessary weed and moss killer. Can the grass cuttings be put on a compost heap that is subsequently used on a vegetable plot?
A: No it would be unwise to do so. The sorts of weed killers they are using could be harmful on a vegetable patch, anywhere near where you are going to be sowing, or on bedding plants. You should talk to the people that are applying it to find out exactly what chemicals they are putting on the lawn, and how harmful they are.
Q: When buying our house we inherited a ten by twenty metre outdoor swimming pool, what can we do with it?
A: You could roof it over to create a sunken greenhouse, with steps going down into it. A problem with greenhouses is that they can be quite ugly, but this would be almost unseen. You could create a formal pool and surround with marginal plants in containers, though you would need to be careful with getting the right depth if you are to plant waterlilies. You should make sure that there are easy entry and exit routes incase small animals are to fall in.
Q: What is the cause of big chocolate spots on Dalea leaves, and what will cure it?
A: Daleas do commonly get a fungal leaf spot. They are more likely to suffer from leaf spot after a damp year like we had last year, but on the whole it is not of massive significance if the Dalea is growing well. They do like moist conditions but they also need light which there was not much of last year. It is worth picking off the odd leaf when you see the symptoms. You could also put on some more pot ash to help toughen the Dalea's cells to fight the leaf spot.
Q: How do you get rid of ivy?
A: You should do a combination of digging and mattocking out. If you want to use a chemical you could try a brushwood killer, but you should be careful when choosing a product to find out how long it will linger in the ground after use. Stopping the flowering and fruiting will stop the seedlings, and clipping it so that it restricts growth is a short-term solution.
Q: Can you suggest fragrant, disease-free plants for a herbaceous border that runs alongside an interwoven fence of about six-foot? The North-facing border gets only early morning sun, then shade for the rest of the day. The ground is dry, possibly because of the three silver birch trees the other side of the fence.
A: You could go for shrubs rather than herbaceous plants as they will suit the conditions better, like winter boxes (sarcococcas) because they do not get very big. The daphne family could also do well (with some added leaf-mould). The toughest daphne is Daphne odora 'Aureomarginata'. The Daphne mezereum is a deciduous plant that flowers in February that could also thrive.
Q: I have been trying to grow carrots for thirty years and the results have been embarrassing. Can you help?
A: Do not use compost for carrots, put them straight into the ground. Sow your carrots thinly and you can cover them over with sowing compost, but you must not dig it over beforehand and any fertility is best watered on when they are already growing. If they are not growing very big it could be because they like to germinate in a sandy soil
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