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Facebook Q&A Session 13th June 2014

Thompson & Morgan Facebook Q&A Session 13th June 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.

  • Simon Gibbins
  • I have an apple tree. When we first moved here it fruited. Now for the last three years it has had blossom on it but all the leaves die and nothing comes.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hello Simon. It’s really impossible for me to say what the problem is without further information such as how and when the leaves die back. For example, curling apple leaves are often caused by pest such as aphids. Take a closer look at your tree to see if you can spot the problem.

    In the first instance, if you can find no evidence of disease or pests then I would aim to improve the growing conditions of your tree. Compacted soil can be critical to the health of a tree, reducing air, water and the availability of nutrients at the roots. You can improve the soil conditions in late autumn by aerating the ground around the root zone. Simply penetrate the soil repeatedly across the entire root zone with a garden fork, preferably to a depth of around 30cm. Remember the root zone may spread beyond the extent of the canopy. Follow this by spreading a thick mulch of organic matter such as well rotted manure across the area but avoid mounding it up around the trunk. Don’t try to dig it in. Just let it break down naturally to improve soil fertility and retain moisture in the soil. This may not solve the problem directly, but will certainly improve your trees health and vigour which will make it more resistant to pest and disease problems.

  • Elizabeth Crowe
  • Can you give me any advice on getting rid of fairy rings on our lawn, they are spreading out in ever increasing circles.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hello Elizabeth. Fairy rings are quite interesting things really. They are caused by a fungus such as Marasmius oreades which grows within the roots of the grass. The fungus causes characteristic circles of toadstools in autumn, but are visible throughout the year as circular areas where the grass dies back. The spores are airborne so there is little that you can do to stop a colony forming in the first instance. Once a colony forms it begins to spread gradually outwards, dying back from the centre and so takes on a ring like appearance. Incredibly, a colony may spread up to 30cm a year! Fairy rings are not particularly harmful in any way.

    In terms of control, I’m afraid that there is little that you can do. There are no chemical controls available. Given that the mycelium grows outwards through the soil then in minor instances you could dig out that area of soil (from beyond the outside of the ring, and to a depth of around 30cm) and replace it with fresh topsoil and turf. However, if you have lots of rings then this would be very expensive and make a horrible mess of your lawn. Being realistic, you may have to learn to live with them, as a colony can survive for up to 100 years! Sorry Elizabeth, that’s not the answer you were hoping for, is it?

  • Elvira Massa
  • We have recently moved and now have a south facing entry porch. I would like to place a plant in there in a big pot to add a bit green when coming in. But what is suited for this situation. It can get very hot in there with the sun on it (it's all windows), but it's not heated in winter. I was thinking of something that was on the bigger side, about 50 cm high or so... Any suggestions what type of plant would do well there?

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hello Elvira, I hope you’ve settled into your new home now. Given that this plant will be under cover throughout the year and therefore reliant on you for water, I would suggest a plant that enjoys Mediterranean conditions - hot and dry in summer, and cold and dry in winter!

    My first thought is Lavender. There are some lovely English Lavenders that will be hardier in winter than the French ones , such as ‘Munstead’ or ‘Hidcote’. Once established these can easily reach about 45cm (18") high. Lavender has the added bonus of being beautifully fragrant, especially in a confined space.

    If you want something a little more formal then maybe some topiary, although you will need to keep these fed and watered more often than Lavender. Box, Privet, and Lonicera nitida all make useful plants for topiary that can be trimmed to whatever size and shape you want. You can always add a splash of colour by adding a few Allium bulbs to brighten them up, if the container is large enough.

    A standard Bay Laurel, Olive or even astandard Holly might also look quite nice. A variegated Holly would give you some year round colour too. There are plenty of plants that will enjoy these conditions. You could even change the containers from season to season, to provide you with more interest. Maybe use colourful bedding in the summer and evergreen grasses, winter pansies or Heucheras in winter. I hope this gives you a few ideas, Elvira.

  • Jonna Cisneros Künzl
  • Hi Sue, I have sown some Judas tree seeds and I have around 10-15 of them growing last two weeks ago, but something was eating the leaves of the seedlings, leaving only the stems and then eventually dying. Two days ago, I have two seedlings left so I repotted it, thinking it was the snails/slugs, but today I checked the two remaining seedlings and I saw very little green insects on its stem, I wonder what are these called and how to get rid of them???

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Jonna. It’s a shame that the picture doesn’t show the damage very well so I can only really guess at the cause. From your description I would imagine that there are two beasties at work here. You are probably correct that your plants have been attacked by slugs or snails. The best thing to do it to protect your seedlings with a sprinkling of slug pellets - you will soon know if they are to blame as you will probably find them dead the next day!

    The green insects that you describe are most likely to be aphids. They tend to be quite prevalent at this time of the year. You were right to squash them. Keep a close eye on your plants, particularly beneath the leaves where they are harder to spot. You can use a homemade spray of diluted soapy water on them or try a shop bought insecticide that is suitable for aphids/ greenfly. Best of luck with your remaining seedlings.

  • Julie Atkinson
  • Hi Sue, I have the perennial collection, arrived at the end of May. Plants are looking healthy but still small. Can you tell me what size they should be before I plant them out in their final place? I don't want them to get lost in beds. Thanks

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Julie. Your perennials where probably miniplugs when they arrived, but they will bulk up quite quickly at this time of the year. Don’t be in too much of a hurry. Remember that they probably won’t produce a great deal of flowers this year. In an ideal world they would be grown on this summer and then planted out in the autumn when the soil conditions are most favourable for plant establishment.

    I expect that you would have potted them up into 7cm diameter pots or similar. Wait until the plants are well rooted in. You will be able to check this by lifting them and looking at the bottom of the pot. Once you can see roots appearing through the drainage holes then you know that the plants are developing a good root system. At this stage you can either continue to grow them in containers until autumn, potting them into larger pots when as and when necessary; or you can plant them into your border - but you will need to keep them well watered if you decide to do this during the hot summer months. Best of luck with your perennial border. It will look fabulous next summer!

  • Carole Green
  • Hi sue, I have got 5 Pieris dotted about in different places in the garden, they have all got black sooty type dust on the leaves. I have tried rinsing with fairy liquid but to no avail. Can you please advise how I could get rid of it, thank you.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Carole. It sounds as though they are suffering from sooty mould, which can be caused by numerous different fungi. Fungal Sooty moulds often occur as a secondary infection where there is already an aphid infestation. Aphids excrete a sticky substance called honeydew which in turn, attracts sooty mould that colonises these sticky areas.

    Firstly you need to check your plant for signs of aphids. They are not always obvious so take a really close look, especially at the growing tips of the shoots where the stems are softest. These can be treated by squashing between your finger and thumb or spraying them regularly with a diluted solution of soapy water. If the infestation is very heavy then you may need to resort to chemicals. Once this problem is under control you will find that the sooty mould will decrease naturally. If you have the patience then you can wipe the leaves clean again with more soapy water but patches of sooty mould will often flake off over the course of the summer. I hope that helps.