Thompson & Morgan Facebook Q&A Session 24th August 2012 - Your horticultural questions answered.

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Name: Amanda Wilkes

Question: I am looking for plants which would be suitable for a small memorial garden, which unfortunately is prone to slugs. It is in a corner of a garden under a tree but gets plenty of sun. Any assistance would be greatly appreciated as the hard work I put in earlier in the year has been enjoyed and digested by the slugs/snails! Thanks

Answer: Oh dear Amanda. I’m afraid that everyone has been fighting a losing battle against slugs and snails this year. The weather conditions have been perfect for them and populations have simply exploded.

Have you tried growing hardy geraniums? They will cope on most soils and provide good ground cover. Try a fairly vigorous variety such as Geranium ‘Rozanne’. You will also find that Astilbe and Japanese anemones are fairly slug free. Look for plants with prickly or hairy foliage and stems such as Pulmonaria and Stachys which tend to be avoided as they are not particularly palatable to molluscs. Strongly aromatic plants such as Lavender are also avoided. Grasses and Ferns are good at resisting slugs too.

Remember that the more mature and better established a plant is then the more resistant to slug attack it will be. With this in mind, it is well worth planting perennials from a 2 litre pot size as these will be better equipped to outgrow any damage that is sustained. I would also use slug pellets, at least while the plants are establishing, to give them a fighting chance. I hope that gives you a few ideas. Best of luck.

Name: Gaz RocknRolla

Question: Over grown allotment weed problem. What would be better to kill off organic way either a Black plastic polythene sheet - 125mu 500 gauge or Heavy duty weed membrane 100 GSM?

Answer: Hi Gaz. If you are aiming to kill of all of the weeds first before planting (which I would definitely recommend) then it would be best to use a black plastic polythene sheet. This will cut out water as well as light, making it just that bit tougher for the weeds to survive. However this method will take a long time to be effective and you will certainly need to leave the plastic in place until next autumn to properly kill off the perennial roots. The idea is to starve the weeds throughout spring and summer when they would normally be in active growth. There is no point in trying to do this during autumn and winter when the plants are dormant, because they will just re-emerge in the spring. Once you do remove the plastic then you will need to keep on top of weeds by hand to remove the roots of any that re-emerge.

Weed membrane is a woven fabric that allows water to pass through it, and this is best used after you have cleared the ground and it is ready for planting. You can cut holes through the membrane to plant your chosen plants and the membrane will prevent weeds growing up around them. This tends to be most effective around permanent perennial borders where you won’t need to access the soil regularly. To be honest it is not ideal for your allotment crops unless you are growing fruit bushes or similar long-term crops.

If you were hoping to use this land next year then I’m afraid you will need to use a different method - organically this means manual hand weeding and hard graft. If you are prepared to put aside your organic techniques just until the weeds are clear then a weed killer would be much quicker, but this really depends on your own views about chemicals. Best of luck with it Gaz.

Name: Steve Linden Wyatt

Question: Question for the wonderful Sue. What tips do you have for looking after strawberries in the winter? Do you suggest covering them in a cloche or would they be ok?

Answer: Hi Steve. Strawberries are perfectly hardy and will benefit from being subjected to some cold weather - this helps to kill off any pest and diseases lurking around them. You can leave them outside in the ground without cloche cover and they will be absolutely fine. The main cause of strawberries dying over winter is when they are sitting in wet soil which makes the crown rot away. Provided that your soil is reasonably well drained then this shouldn’t be a problem.

If your strawberries are planted in containers then there is a risk of the compost freezing and damaging the roots. It might be worth moving the containers against the house or next to a sheltered fence or wall just to give them a little protection. Hope that helps, Steve.

Name: Udaya Kumar

Question: Hi can you please tell what chemical to control leaf miner in beans and wattex.

Answer: Hello Udaya. Unfortunately I’m not really in a position to advise you on chemical controls as I notice that you are in India where there will be different legislation regarding chemicals to that in the UK. Also I suspect that many of the products available to you will be different to those over here. However I have read that Neem oil (which is often used as in insect repellent), may interfere with the life cycle of leaf miner - so maybe this is worth a try. If only a small area of your crop is infected then you can remove the infected leaves by hand and burn them. You can also try covering the soil around the plants with a plastic mulch to act as a barrier which will prevent the larvae pupating into adult flies. I hope that this points you in the right direction. Sorry that I can’t be more specific.

Name: Lydie Taylor

Question: A question for the experts. 15 yrs ago I planted a custard apple seeds and several began to grow. One outgrew its pot and I planted it in my mum’s large garden to see what would happen. Each time I visit it has grown, and this yr it is easily 10foot tall. She is now moving and I know whoever moves in will look at the ugly tree in the corner and remove it! They won’t know its story! Is it possible to remove a tree at this size (I have read eye masks are essential when handling!) and replant and would it enjoy a northwest coastal garden? It currently resides in a north facing woodland garden in Nottinghamshire. Here it would face west.

Answer: Hi Lydie. It sounds as though your custard apple is thoroughly enjoying your Mum’s garden. To be perfectly honest it is probably best left where it is. Moving it would be a large job and a plant of this size is unlikely to appreciate being uprooted from its current position. I would also be cautious of moving it to a coastal west facing position as this is more likely to be exposed to drying winds and extremes of weather. Its current woodland position is probably offering it the shelter and humidity that this plant needs in order to thrive. Maybe it’s time to grow some more from seed and start afresh?

Name: Daz Mad Head Gilbert

Question: Do you cut back all your raspberries canes? Or just the ones that have given fruit. I’m a novice at this. Plus do you sell support fencing for them?

Answer: Hi Daz. It depends on what variety you are growing. If you are growing a summer fruiting variety then you only cut back the canes that fruited this year. You can do this over the winter - February is a good time. Leave any young shoots that have appeared from the base of the plant this summer and tie them in to the supporting wires. These will become the fruiting canes for next year. However if you are growing an autumn fruiting variety (which will just start to be ripening about now) then you can cut all of the canes back to ground level in February, as these will fruit on new canes produced in the spring.

Regarding your query about supporting fencing, the easiest method is to bang a post into the ground at either end of your row of raspberries and then attach wires horizontally between the posts.

For more information about growing raspberries take a look at our ‘How to grow raspberries’ article.

Name: Tracie Watson

Question: I bought my raspberry bush months ago (more like a twig to be honest) planted it following instructions but nothing has changed, it's still a twig help anyone x

Answer: Hi Tracie. That’s very disappointing. I planted some this spring and they have put on some astonishing growth - I would have expected yours to do the same. If your raspberry plant is still a twig and has no foliage on it then I think that you can safely assume that it has died. You can confirm this by scratching the surface of the bark with your thumbnail to see whether there is any trace of green beneath. If not, then your plant is dead.

However, if there is some foliage on your plant, but it just hasn’t got off to a very good start, then I would suggest that you leave it for this year and let it get established. Hopefully in spring you will start to see some new stronger growth appearing from the base of the plant. It may just be taking its time to settle in. If you see no strong growth in the spring then pull them out and replace them with new, more vigorous plants. Best of luck with them.

Name: Raju Patel

Question: I received my Gardenia plants and have potted them in John Innes 3 compost and water as required. However the leaves are turning black and dropping. How do I correct this?

Answer: Hi Raju. It’s always much easier to give an accurate diagnosis of the problem if you are able to provide a picture. Without seeing the plant it’s hard to say what is causing the problem but it’s always a good idea to review the plants growing conditions as a starting point. Physiological conditions such as overwatering and cold temperatures can cause foliage to become discoloured and fall from the plant. Take a look at your gardenia and ask yourself the following questions. Is the compost very wet/ dry? Is the plant getting enough light? Is it located in a very windy spot? Make any changes that are necessary. You can check the required growing conditions on the individual product pages on our website.

The other obvious possibility is that the plant is suffering from sooty mould. Take a damp cloth and see if the black colouring wipes off of the leaves. If so then this is a fungus that grows on the surface of the leaves and prevents the plant photosynthesising in severe cases. Sooty mould is generally a secondary infection that colonises leaves which are covered in clear sticky honeydew (aphid excretions). Therefore the presence of sooty mould is generally an indicator that your plants are also/ have recently been infested with aphids. Clear the aphid problem and wipe the leaves clean to rectify the problem. If you are still uncertain of the cause of the problem then you can post a picture on our facebook wall and I will try to give you a more precise diagnosis.

Name: Kevin Joseph

Question: Hi, I am currently growing 'black cherry' tomato however the tomatoes themselves aren’t going a dark purple colour like the pictures on your site, they stay orange. What could be the reason for this?

Answer: Hi Kevin. That’s rather odd as ‘Black Cherry’ tends to ripen from green to a green-red colour through to a rich mahogany shade. I wouldn’t expect to see them orange at any point. Are you certain that you have not got your labels mixed up anywhere? This variety is not normally a particularly heavy cropper so if you have a good crop of orange tomatoes then there is a distinct possibility that these are not ‘Black Cherry’ tomatoes. I’m afraid that I can’t think of any other likely reason for them ripening to the wrong colour.

Name: Malcolm Walker

Question: How do I overwinter "Lady in Black" climbing fuchsia?

Answer: Hello Malcolm. If your plant is well established in the ground in a sheltered part of the garden then you can apply a deep bark mulch around the base of the plant in autumn to protect the roots from winter cold. During very cold periods it is advisable to throw some horticultural fleece over the plant at night for an added layer of protection.

However, if your plant is growing in a large container then it is likely to be more susceptible to damage caused by the cold. If possible, move the container to a sheltered spot against a house wall which will give it some protection, or pop it into a cold greenhouse if you have the space.

Don’t prune the plant back until you see new buds breaking in the spring as there is likely to be some dieback of the stems over winter - this is perfectly normal in hardy fuchsias and they do tend to look pretty awful over the winter months! Once you can see where new growth is breaking from then you can see how much of the stem to prune out. Hope that helps, Malcolm.

Name: Ann Doris

Question: I would like to plant a tallish plant in a pot. Where I want to place it is very windy could you please advise me?

Answer: I would like to plant a tallish plant in a pot. Where I want to place it is very windy could you please advise me?

Answer: Hi Ann. I think it would be best to choose either a shrub or some grasses in this situation as they are generally the most wind-tolerant plants. You could try Heather (although make sure you plant it into ericaceous compost), Euonymus japonicus, Privet (Ligustrum), Holly, Skimmia, Viburnum, dwarf conifers or Rosemary. If you can find dwarf versions of these shrubs they would be more suited to container cultivation but with regular pruning even the full-size varieties can be kept within bounds. You could also try Purple Moor Grass (Molinia caerulea) for a contemporary look – these are very wind tolerant and suitable for container cultivation. Other good grasses include Stipa tenuissima (Mexican Feather Grass) and varieties of Miscanthus sinensis. I hope this gives you some ideas Ann!