Thompson & Morgan
Facebook Q&A Session 30th May 2014

Thompson & Morgan Facebook Q&A Session 30th May 2014
- Your horticultural questions answered.

Our horticultural expert Sue Sanderson runs a fortnightly question and answer session - so if there is something that has been eluding you in your garden, post your question on our facebook page and she will get back to you during her next Q&A session.

View the answers to our previous sessions.

  • Lucy Garden
  • I have some rose bushes in my garden that were left by the previous owner. A couple of them seem to have flowers with very floppy stems - they're not strong enough to hold up the flowers. Is this just a problem with the varieties I'm growing - but there are two different (unknown) ones with this problem, growing near each other - or are they short of minerals or trace elements, which would help them hold their heads up properly? They are growing on clay and I don't cosset them.....but my other roses seem fine with similar unkind treatment!

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Lucy. This is quite a common problem with roses, particularly the large flowered English Rose types. It is simply because the bid puffy flower heads are too heavy for the stems, particularly in wet weather. This is their normal growth habit and tends to improve as the plant matures. You can help to prop them up by inserting a few twiggy sticks discreetly around the bush to hold the growth more upright.

    Insufficient sun can also be a contributing factor to weak spindly growth. It may be worth reviewing the position of these roses and moving them in the autumn if necessary.

    You can encourage stronger growth and thicker stems by pruning them back in winter by no more than a half. Don’t worry about your soil type - roses growth well on clay. They are quite greedy plants however, so an application of slow release fertiliser in spring and autumn will be beneficial. I hope that helps you Lucy.

  • Robin Woodford
  • Sue, I have a tree peony which I bought from your company 2 years ago. It does not seem to progress at all. It is still a small pathetic looking plant and has never flowered. I was thinking of replanting it but I would like to know what sort of compost to fill the new hole with. Best wishes Robin

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Robin. Tree Peony’s are notorious for being slow to flower. They really need to be well established before they start to produce blooms and this can take 3 years or more. It’s also worth checking that they are growing in suitable conditions and making improvements where necessary. If conditions are unsuitable for the plant then it may be better to move it, but remember that this will delay establishment further still.

    Here are a few tips. Tree Peonies are at their best in sunny positions and won’t do well in shade. They also need shelter from cold drying winds and strong early morning sunlight. Check the soil isn’t too wet as the plant will struggle and eventually rot - Tree peonies like moist soil, but it must be well drained.

    If you do decide to replant it then you can mix some ordinary multipurpose compost into the soil before you dig your hole. Don’t be tempted to backfill the planting hole with just compost - it needs to be mixed thoroughly with your own garden soil. It’s important that the peony is planted so that the grafted union sits at least 10cm (4") below the soil surface. I know that this sounds very deep but it is necessary as shallow planting may hinder establishment and delay flowering.

    Feed your peony with a high potash fertiliser during the growing season as they are heavy feeders. The potash will encourage flower production. I hope that these tips help you. Tree Peonies do require a lot of patience but they are well worth the wait!

  • Ray Ormsby
  • Every year we have more and more ants in our garden - the lawn has more and more nests. I use ant powder but it doesn't seem to work. Any ideas? Ants are generally quite beneficial in the garden as they feed on sap sucking aphids and the honeydew that they produce. But I can appreciate why you wouldn’t want them living in your lawn.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • There are numerous products on the market from powders to gels that can be used to kill a nest. I believe that the gels are often found to be slightly more effective so it might be worth trying one of them during a period of drier weather. You can also buy nematodes that are watered onto the area and these are found to be very effective too. You could try the old fashioned remedy of pouring boiling water over the nest - this will certainly upset them but also tends to kill the grass leaving unsightly bare patches!

    The other option is to find a way to live with them. You can reduce the mess made when mowing by raking over and excavated soil mounds on a dry day prior to mowing. If you can encourage birds into your garden then they will readily dispose of any ants and eggs that are brought to the surface by this process. I hope that one of these suggestions works for you Ray. If all else fails, try watching them for a while - they are fascinating insects and you may even grow to like them!

  • Jane Wells
  • I have an ornamental cherry tree in the front garden and its leaves have started going brown but not falling off, it is on three branches so far, is it dying? The tree is about twelve foot tall and has been in ten years. It is Autumnus or something x

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Jane. It sounds as though your tree is definitely struggling. Without seeing it or having a little more information, it is almost impossible to say what the cause is. I would suggest that as it has been there for 10 years already and the damage is fairly localised then the cause is likely to be a disease of some sort, such as cherry leaf scorch. However it is still worth checking that there is no obvious mechanical damage to the tree, and no obvious changes to its growing conditions. If you have some pictures or can describe the symptoms in more detail then it might be possible to give a more precise diagnosis.

    It’s hard to offer a solution without having a proper diagnosis. I would certainly suggest that you rake up any fallen leaves and burn them to prevent the spread of any fungal spores. Trees are often more resilient than we anticipate and capable of compartmentalising wood within their branches to prevent the spread of decay and disease that may have entered the branches themselves. Don’t despair just yet - it may well survive, even if it looks a bit scruffy this year!

  • Diane Allen
  • Can you recommend a small, upright-ish growing ornamental tree for our front garden please. Not too wide a canopy - don't want one that casts too much shade. It will be in a south facing garden. Reason - I have to replace a winter flowering cherry that has died of old age and need a similar open branched, delicate looking tree - but not a cherry again. Thank you.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Diane. I’m going to recommend one of my favourites - Sorbus vilmorinii (Vilmorins Rowan). I love this species! It has delicate ferny foliage, panicles of creamy white flowers followed by pink-red berries and astonishingly good autumn colour. Better still, it has a small canopy and an open habit. What more could you ask for?

    You might also consider one of the smaller crab apples but I should warn you that crab apples can be quite messy when they drop their fruits, so these are not great for paved areas! How about Amelanchier ‘Ballerina’? This is another good small tree for a long season of interest with pretty spring flower and lovely coloured foliage. Acer psuedoplatanus ‘Brilliantissimum’ is a good choice too and has lovely autumn colour, or you might like Acer griseum for its beautiful peeling bark. I hope this gives you a few ideas as a starting point. Let me know what you decide upon.

  • Carly Seaman
  • I have a dark red palmatum acer which is in a pot. It will come out in all its glory for about a month, then the leaves go brown and curl at the edges. Any ideas why this is? I have tried different positions.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • This is a very common problem with the finely cut foliage of Japanese Maples. It is caused by too much sun or exposure to drying winds. They are best grown in a sheltered spot in the dappled shade of taller trees.

    If you are growing it in a container then try to ensure that the compost is kept evenly moist throughout the summer as dryness at the roots will also have this effect. Avoid water the plant over its foliage however, as this may also damage the foliage.

    It’s a shame that you are only able to enjoy this tree for such a limited time. Hopefully you can find a more suitable spot for it in your garden. If not, then perhaps try one of the Japanese Maples with less finely cut foliage as these are slightly more resilient. Best of luck with it Carly.

  • Teresa Duncan
  • By our front door, in a pot, we have a shaped buxus. It seems to have some white dust type particles deep within it. Otherwise healthy with new green leaves and no sign of box blight. Any ideas if this is a fungus type issue?

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Your Box plant may be suffering from Box aphid. These little aphids can be identified by the white, sticky dust that the nymphs excrete. In severe cases, this white dust may look like a dusting of talcum powder and will puff out of the plant if it is brushed past.

    Box aphid lays its eggs in late summer and the nymphs hatch in early summer of the following year and create this dust like substance. By midsummer they will have matured and left the plants. At this point the plant will often have a noticeable growth spurt.

    Although a bit unsightly, these aphids are unlikely to cause much damage to your plant, except for a few misshapen leaves. Your Box plants will always withstand pests and diseases much better if they are kept healthy so it’s worth keeping them well feed and watered throughout the growing season. I hope this answers you question.

  • Jenny Erby
  • Both my damson merry weather variety and my sloe bushes are loaded with fruit but both have some deformed fruit larger than the other fruits. What is this, what do I do about it, will it spread? I have been removing the ones I can reach. This is the first year both have fruited other than one lone fruit so keen to keep them until they ripen.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hello Jenny. It’s always tricky to diagnose a problem without seeing it first. Deformed and enlarged fruits in Prunus species (including Damson and Sloe) can be caused by a fungal disease called Pocket Plum or Taphrina pruni. The fruits become elongated and hollow, and don’t develop a stone within them. Later in the season they fail to ripen and eventually become covered in white spores, before shrivelling up and dropping to the ground. You may also notice that twigs bearing these deformed fruits also show some thickening and deformity. This fungus is also responsible for the condition known as witches brooms in which a dense mass of live and dead twigs are produced in one spot giving the appearance of a birds nest.

    Chemical control is usually unnecessary. You can normally control the disease by cutting out any deformed twigs, witches brooms, or infected fruits before they develop spores. Burn any infected material or dispose of it in your general waste - but don’t add it to the compost heap. Hopefully this will control the disease sufficiently for the rest of your crop to ripen.