The second in our series of questions and answers from Pippa Greenwood. Please remember we are open for more questions at the bottom - just leave a comment and we'll get our panel of experts to answer your questions.
Q: How can I keep my greenhouse a bit cooler in the height of the summer?
A: Make sure that greenhouses and conservatories have adequate shading – temperatures soon soar in this warmer weather and plants inside will dry out rapidly and may be severely scorched. Paint on shading is the cheapest and is readily available from the garden centre but a conservatory is better fitted with more attractive looking blinds in the long term. Keep vents and windows open as much as possible too so that cooler air can come in. Try to allow a through draught, and even consider fitting an extra window or vent. The old-fashioned remedy of ‘damping down’ works brilliantly too – simple water any hard-standing such as the path in the greenhouse, as the water evaporates it uses heat energy and so temperatures drop.
Q: There is ivy growing up through my well-established hornbeam hedge, will it harm the hedge?
A: Much as I love ivy (and am not one for removing it from trees), if the ivy is starting to get a hold in your hedge, I’d be inclined to try to remove it. It is a vigorous plant and although I’m sure it won’t kill the hedging plants, it can start to swamp them and may lead to a degree of gappyness in the foliage covering as the hedge comes in to full leaf. The easiest way is to try to dig out the ivy at the base, or failing this, to sever the stem from the base, and then pull off the dead ivy plants once they have turned brown.
Q: My hostas are riddled with holes, any suggestions?
A: Hostas and holes pretty well always means slugs, and possibly snails.
If they are growing in pots try using a copper based paint or a self-adhesive copper tape applied around the rim of the pot – slugs and snails hate crossing copper. If they are in open ground I suggest you try setting traps eg beer traps, and also consider using a nematode biological, or an organic slug control as this way you can kill them off without endangering the wildlife.
Q: Can I grow a rose in a pot?
A: yes, you can. But looking after it will definitely be much more effort than if it were growing in open ground! If you cannot plant it in open ground then I suggest you use as large a pot as possible, ideally something like a half barrel, and use a loam-based compost with added grit, something like John Innes number 3 would be good, plus some horticultural grit.
Q: How do I know what size containers to use for my patio veg. I have a tiny flat with a small balcony and need to be as space-saving as possible?
A: Assuming the balcony is up to the job (and please do check first!!) the bigger the better, but generally speaking I find pot-shaped containers work better than growing bags as they allow you to put in a top quality compost, and are easier to keep moist. A minimum of about 30cm3 , but ideally bigger is what I would recommend. If space and weight are an issue, then try the crop bags made from a sort of plasticised hessian material as these are very light weight, available in a range of sizes, fold flat and tiny for off-season storage, and have brilliant drainage holes in them!
Q: I’ve just noticed that my apple tree has several areas on it where the branches are all bobbly and swollen. They seem to be coming in to leaf OK. What is this?
A: It sounds as if they were hit by woolly aphid. This sap-sucking pest causes you stems to swell and distort as it feeds, but its a symptom that is often first noticed when the plants start to grow in the spring. Once this damage has appeared the infested stem may start to die back, especially when the damage is severe, or if apple canker disease gets in via the wounded bark. I suggest you prune out the worst affected areas.
Q: Pippa, is it too late to sow peas in March?
A: Its certainly worth sowing some peas in March. In many areas, the soil stays so very wet and so extremely cold well into March. So for much of the country sowing any earlier is not possible! If the soil is still a bit wet and cold where you are, I suggest you sow the seed in cells, root-trainer pots or small flower pots and then transplant the peas when the plants are three or four inches tall and things have warmed up a bit. Remember to get some twiggy sticks in to the soil when you sow the seed or plant the young peas out, these will act as supports as the peas grow.
Q: Is it true that it is not a good idea to cut an established hedge in spring. If so, why?
A: Its certainly true. In fact as the bird nesting season has officially started in spring, it is actually illegal to do anything which might disturb nesting birds! The hedge itself would not mind. But you could very easily cause tragedy as far as the wild birds are concerned.
Q: Some of my seedlings have suddenly died, sort of flopped over, can I save them?
A: The most likely cause is damping off disease. This is caused by fungi, often introduced via unclean compost, trays or pots, or from non-mains water. Sadly there is no way you’ll be able to resurrect the seedlings but do check on your gardening hygiene. Its also worth watering seedlings with a dilute copper fungicide. This can help to prevent the infection getting a hold in the first place.
Q: The winter has left my lawn riddled with moss, what can I do?
A: First try to alleviate any compacted areas using a fork driven in deeply at intervals over the lawn. Then if you wish you could use a proprietary moss killer. Once the moss has been killed off, and after the delay period suggested on the pack, rake out the dead moss.
Don’t do this any earlier than suggested or you may end up spreading the moss! If areas are very thin, you could then roughen up the surface and re-seed with fresh grass seed. Good lawn care ie feeding, scarifying and adequate water are the real key to a moss-free green carpet!
Once again Pippa has given us a bonus question:
Q: Pippa, I am fed up with all the caterpillars I get in my brassicas, especially the calabrese. Please, please suggest a chemical free solution?
A: I never spray mine either, but with out a physical barrier you can guarantee a good crop of caterpillars! I plant low-growing brassicas under fleece or fine net pull-out tunnels. Taller ones a brilliant metal frame which comes with a fine mesh ‘jacket’ and a zip-up doorway. This is great because it is just tall enough for me to get in and so amongst the crop. It makes it very easy to harvest just what I want. Mesh covers like this will also protect against other flying pests such as aphids, cabbage root fly and flea beetle. They make organic veg growing so much easier!
We cannot thank Pippa enough for these valuable tips and answers. Please add your own questions and we'll try to help.