Thompson & Morgan Facebook Q&A Session 28th July - Your horticultural questions answered.

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Name: Pauline Irvine

Question: Hi I've a red rose that flowered beautifully in it's 2nd year but someone beheaded it on me and for the last 2 years the bud has come up but it doesn't open, any ideas? It's still continuing to grow but the bud just doesn't open and there's only 1 bud on it each year.

Answer: Hi Pauline. It is unlikely that beheading it would prevent it from flowering in following years but there are quite a few reasons why roses might not flower. Often it is something to do with their growing environment so it’s worth reviewing this.

Firstly take a look at how much sun it is receiving. Has the surrounding vegetation started to shade it over the last couple of years? Many roses prefer at least 6 hours of sunshine a day to flower well, so you might need to move it this winter to a sunnier spot.

When was the last time you fed it? Roses are greedy plants and enjoy a rich soil. If you have not fed it recently, then start giving it a balanced fertiliser every few weeks throughout the rest of the summer. Next spring, spread a good layer of well rotted manure or garden compost around the base of the plant too. If you have already been feeding it then check the nitrogen content on the feed you are using. Too much nitrogen can cause lots of foliage growth at the expense of flowers.

Did the flower bud swell but fail to open properly. This could be ‘capping’ or ‘balling’ which is caused by heavy rain or hail. A period of cold or drought during bud development can also prevent proper buds from forming or opening. Obviously there is little you can do about the weather but you can make sure that it is well watered during dry periods. I hope that one of these suggestions rings a bell with you. Pauline. Hopefully it will flower for you next year.

Name: Denise Glover

Question: I have a clematis that flowers from summer to autumn,{sorry not sure what its called} its stunning but about a foot of the base from the soil is all brown and dead. Does anybody know how i can rectify this for next year’s growth. Thanks

Answer: Hi Denise. It sounds to me as though your clematis is thriving. It is quite common for the lower part of a clematis stem to become woody as it matures. They often start peeling and it may look as though thin fibrous strings of bark are flaking away - don’t worry, this is absolutely normal.

Name: John Goss

Question: A friend of mine keeps finding small mounds in his lawn - sand like mounds that seem to be appearing in different places. Any idea what might be causing these mounds? Ants seem to have been ruled out as they can't be found on/near them and they seem to small for a mole.

Answer: Hi John. How fascinating. The normal cause of soil being pushed to the surface is earthworm activity, but what you are describing does sound rather different. I think that Wes could be right when he suggests that this is a sign of tawny mining bee activity. They are mainly distributed throughout southern and central Britain, and are active between April and September. Tell your friend to keep his eyes peeled for them as they are fairly easily recognised with their bright orange fur!

Name: Trudi Sagar

Question: After filling our new raised veg bed with stuff which is doing really well so far, we are thinking what we could use the bed for in the Autumn/Winter - can you recommend anything we could get started now so that when we pull our carrots, parsnips, beetroot, onions and leeks we can fill it again - also, what do people put in their greenhouses over winter? can we grow anything to maximise it's use? Thank You!

Answer: Many Brassicas make ideal winter vegetables. Try sowing Cabbage ‘Advantage’ or ‘Durham Early’  for harvesting in spring. Similarly Kale also makes an excellent autumn/ winter vegetable and some varieties, such as ‘Black Tuscany’ can be quite attractive.

Hardy lettuce ‘All the Year Round’ is a great crop for sowing now for winter salads. You could also try onions  and garlic for autumn planting. What about Swiss chard for a colourful crop?

What you can grow in the greenhouse will really depend on whether you decide to heat it or not. If you keep it frost free then you can grow salad leaves or try some Spinach ‘Scenic’. New varieties of carrots such as ‘Nantes Frubund’ are also ideal for sowing under cover. You could also plant some second cropping potatoes  in bags outdoors now, and then move them into the greenhouse before the first frosts. Hope that gives you some ideas.

Name: Christina Goozee

Question: More mould. What did I do wrong as this is the 1st year this has happened, even with a good edible crop.

Answer: Hi Christina. The most common cause of this type of damage is the fungal infection Brown rot. It appears particularly during wet a wet season causing small brown spots on the flower petals, stems and fruits where it normally where the spores enter the plant through minor lesions. As it the fungal infection progresses it causes sunken brown cankers on twigs where the rotting fruit touches them, and rings of grey spores on the rotting fruit. The fruits will eventually shrivel and become mummified, remaining on the tree over winter. The spores overwinter in the fruits and stem cankers before releasing more spores the following year.

It is too late to do much about it this summer but in autumn you should collect up all of the infected fruits from the tree and the ground and destroy them. Once the leaves have fallen you can also take a look at the stems and prune out any cankers that might harbour spores over winter. In spring, you can also try spraying the tree with a fungicide at the beginning, peak and end of flowering. Use a fungicide that contains the active ingredient difenoconazole such as Westland Plant Rescue Fungus Control. Hopefully this will clear many of the spores before next years crop develops. Best of luck Christina.

Name: Anna Mason

Question: Hi T&M question for Sue should I cut down the leaves of bearded Iris they are in one of my ladies gardens and she wants me to but I thought they should be left to feed the rhizome.

Answer: Hi Anna. You are quite right to leave the foliage in place. Removing foliage now simply prevents the plant from photosynthesis and therefore starves the rhizome until new foliage is produced. It will die back naturally in autumn and you can remove it then. All you need to do at this time of year is to remove any faded flower stems.

Name: Anna Mason

Question: Another for Sue - Chrysanthemums for cutting. I have just dug mine up as they were struggling and being eaten they are now in containers. What compost is best and what growing conditions. They were very leggy (even though I pinched out) and the tops broke when I moved them. I have cut them back as I decided they need a short kip having been rudely moved. They weren’t yours they are from Blooms.

Answer: Chrysanthemums enjoy a fertile, well drained, neutral to acid soil that is enriched with plenty of well rotted manure. Grow them in a sheltered position in full sun. If you are growing them in containers then young plants can be started in pots of John Innes No. 2, before transplanting them up to larger pots of John Innes No.3 as they increase in size.

Some varieties of Chrysanthemum are naturally quite tall and will require staking to prevent the stems from being damaged. If they are not a hardy variety then you will need to cut back the faded stems in autumn, and lift the crowns. Store them in fresh compost in a frost free position, until they can be replanted in spring. The short hardy varieties can be left outdoors overwinter. In late autumn the application of a deep mulch will help to protect the crowns of the plants from winter weather. Hope that helps Anna.

Name: Louise Rowley-Spendlove

Question: Overwintering Onions from seed. Is this best started now in cells or in the ground next month? How do they cope with root disturbance? What can i interplant these with?

Answer: Hi Louise. You can sow onions in modules quite easily and they will transplant perfectly well. We sell a variety call ‘Hi Keeper’ that can be sown in September. However most people grow overwintering onions now from sets which is much less bother. You could try the Japanese variety ‘Senshyu’  or ‘Shakespeare’.

Your question about interplanting is a tricky one. The problem is that most winter hardy crops such as Brassicas and garlic really require their own space as they are not fast growing crops. There are winter salad crops that you could grow but these really need cloche protection. The main reason for interplanting is to maximise space by cultivating a quick growing crop that can be harvested while its neighbours are still growing. In the summer this can be a great benefit as space is normally tight on most people’s vegetable plots. But in the winter there is normally much more space available so intercropping isn’t really necessary.

Name: Liz Cable

Question: Hi I have planted parsnip seed twice this year and as a result have about 6 parsnips. I know it's dry, but I have kept the rows well watered, but nothing is coming through - I know they're slow to germinate but about 6 weeks have gone by now. Help!!!!

Answer: Oh dear Liz - don’t be too disheartened as I have had exactly the same problem this year. It is particularly frustrating because last year my crop was superb! It’s a bit late to be sowing again now but here are a few tips for next year.

Always, always use fresh seed. Parsnip seed loses its viability quickly and last year’s seed is unlikely to have a good germination rate. Parsnips prefer a deeply dug, rich fertile soil that is slightly on the heavy side. Don’t be tempted to add manure just before you sow as this can cause canker. Your best bet is to manure the soil well in the autumn so that it has plenty of time to break down in the soil before you sow. You are right to keep them well watered especially at germination and in the early stages of development. In dry conditions you can help them along by giving the seed drill a good soaking before you sow the seeds. This will keep them nicely moist from the very start. A lot of people find success by pre-germinating the seed on the surface of some wet kitchen towel, much as you would with cress. You can then transfer them to old toilet rolls filled with compost to get them going, before transplanting the whole loo roll into the ground where it will rot down. I have never tried this method myself, and it sounds like a bit of a fiddle, but it might be worth a go. I hope you have better luck next year.