Thompson & Morgan
Facebook Q&A Session 2nd May 2014

Thompson & Morgan Facebook Q&A Session 2nd 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.

  • Jane Scorer
  • Hi Sue. Helppppp! My year old Rosa Garden Party plants were fine and healthy last autumn but have developed dreadful powdery mildew after our wet winter. I was hoping that drier weather coupled with new fresh growth would overcome this problem but they are still looking very sad. I try to garden organically where possible, but would consider anything to save them!

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Jane, you’re absolutely right – this fungus thrives in moist and humid conditions. Soft new growth can be prone to attack so it is recommended to use a low nitrogen fertiliser if you’re feeding your roses. Luckily rose powdery mildew mainly grows on the surface of leaves and stems so there are a number of organic substances you can use to control it such as those based on natural plant or fish oils. You’ll see these sprays labelled as 'organic', such as Vitax Organic 2 in 1, and they will list on the back whether they control powdery mildews. You’ll probably need to spray several times throughout the growing season to maintain control. Make sure you spray plants in early autumn too as this may help control the amount of overwintering spores. If you feel the need to use chemicals then try sprays which contain difenoconazole or myclobutanil, such as Westland Plant Rescue Fungus Control or Bayer Garden Systhane Fungus Fighter. They are systemic (enter the vascular system of the plant) so will provide 2 or 3 weeks protection per treatment. I hope this helps Jane, best of luck.

  • Tracey Williams
  • Hello sue, we have a plum tree which is only three years old. Last year we saw our first sight of a plum (only two) but they shrivelled up and dropped off. We had some terrible leaf curl last year which seemed to be aphids. The same thing has happened already this year complete leaf curl with aphids in the curled leaf. There are also ladybirds on the tree but they can't keep up with the extent of the problem. Please help thank you.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Tracey, this does sound like plum leaf-curling aphids which are most active in mid to late spring. In summer they can also be followed by mealy plum aphid. The stress of heavy infestation by these aphids could be causing the tree to abort fruit so it’s best you tackle the problem to ensure good crops. The best way to control leaf-curling and mealy aphids is by using a systemic insecticide containing thiacloprid, such as Bayer Provado Ultimate Bug Killer. This spray is safe to use on edible crops and fruit trees, although never spray while the tree is flowering - wait until afterwards. For heavy infestations, spray several times throughout the growing season, at the recommended intervals and take care to stop spraying a number of weeks or days before picking the fruit (check the label for further advice). Mealy plum aphid (pale greenish-white in colour) can also be treated with sprays containing lambda-cyhalothrin or pyrethrum such as Westland Plant Rescue Fruit & Vegetable Bug Killer. You can also tackle the overwintering eggs by applying a winter tree wash on a dry day in winter – they’re available in all good garden centres. This dual approach should help to bring the problem back under control. I hope this helps Tracey, let us know how you get on.

  • Jill Wheeler
  • I've sown some Okra seeds & the seedlings are just coming up - can you offer some advice on how to nurture these plants successfully? Should I keep them in the greenhouse? Pots/ground etc? I did one in a pot last year but only got 2 okras.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Jill, okra is a tropical or sub-tropical plant so will produce the best crops in a greenhouse. They are sensitive to frost so are best grown on in warm conditions until ready to plant in their final position. Okra will grow in a sheltered sunny spot on the patio but cropping won't be as prolific, particularly if we have a cool summer. They will be perfectly happy in pots, grow bags or the ground, similar to tomatoes and cucumbers. Place the okra somewhere bright, making sure they’re not shaded by other big plants and ventilate the greenhouse on hot days to allow good air flow. Once the plants start flowering, feed them weekly with a potassium-rich fertiliser such as tomato feed or a general high potash fertiliser, following the instructions on the packet. Hopefully with a little heat, fertiliser and plenty of light you should get a bumper crop this year! I hope this helps, good luck.

  • Elaine Galer
  • Hi Sue, I'm a trustee of the charity Save Hemsby Coastline. As you are probably aware, we lost a large amount of sand dune (the village's only coastal defence) and several homes during the storm surge in December. We are looking to transplant marram grass onto the denuded dunes to try to build up sand defences. Any advice please?

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Elaine, sorry to hear about the devastation to your village caused by the storms – I have taken a look at your very inspiring website. As you’ve found, any work to the coastline is quite specialist, requiring planning permission and an understanding of the local ecosystem. Marram grass is a great natural defence, having an extensive fibrous root system, which binds the sand together. However it can take several years before these benefits are realised, while the young grass establishes. I have limited knowledge of marram grass although I am aware that specialist nurseries can supply cell-raised young plants and should provide detailed planting advice. From what I have read seed is difficult to establish due to the ever-changing nature of the dunes and bare-root plants have limited success in comparison to module or cell-raised plants. The most important thing is to protect and nurture these young plants while they establish by preventing trampling, and perhaps even applying a slow-release fertiliser to help them get started. They will also grow most vigorously if sand can accumulate and bury the plants as they grow (as would happen in nature) – this helps them build up complex and deep root systems. Planting small bundles of dead reed or similar amongst the marram grass can help sand accumulate and these will naturally break down over time. It may also be a case of gradually planting the dunes over time, replacing any young plants which have failed and filling large gaps as the plants grow. There is some excellent information about planting on this grower’s website: Cheviot Trees and the Scottish Natural Heritage website. I hope this helps Elaine – best of luck with the project.

  • Jane Wells
  • Hi Sue, I have grown the Cup and Saucer Vine from seed every year with no problems but this year the seedlings come through and just as the second leaves grow they wither and die. I have sown a second lot in new compost and sterilised pots but the same is happening again. All the rest of my plants are perfectly fine .Thanks x

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Jane, this sounds most like damping off, although it’s strange that no other plants have been affected. Damping off is a fungal disease caused by a variety of water moulds that flourish in wet compost and need water to spread from plant to plant. They penetrate the plant cells and cause plant collapse which looks like wilting. These fungal diseases can easily be introduced in compost or rainwater and take hold when presented with moist and humid conditions. Try watering the compost sparingly after sowing the seeds and allow the compost to dry out slightly between watering to reduce the risk of damping off. Take care to keep them away from cold chills too as they are tropical plants. If you think there may be an issue with the seed please contact our customer care team by emailing ccare@thompson-morgan.com or phoning 0844 573 1818 and they will be able to arrange a replacement for you. I hope this helps Jane, let us know how you get on.

  • Daniel Hollywood
  • Hello sue how do you stop the leek moth? My leeks last year got hit by it and were devastated. Don't want it to happen this year. Many thanks, Dan.

  • Sue - T&M Horticultural Expert
    Sue Sanderson - T & M Horticulturalist
  • Hi Daniel, I feel for you on this – it is so devastating to have your crop ruined. Unfortunately there are no chemical controls for leek moths. The only way to stop them is to erect a physical barrier over the area to prevent the female moth laying eggs. You can use either horticultural fleece or ultra-fine Enviromesh. If you spot any white cocoons at any point then squash them! Best of luck.