Thompson & Morgan Facebook Q&A Session 11th November - Your horticultural questions answered.

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Name: Jackie Galliford

Question: Can you tell me what is eating my plant?

Answer:

Hi Jackie, there are a few pests which could be chewing the leaves on your plant. If you can’t see any slime trails left by slugs and snails then the most likely candidate is earwigs, as the holes have appeared in the centre of the leaves, not just around the edges. It could also be some sort of Sawfly larvae (which look like small caterpillars). You may find it difficult to spot the culprits at this time of year as they may have gone into hibernation. However I’ll give you some advice just in case - or for next year.

Earwigs start to feed once the weather becomes warm in spring. They are active at night so you’re unlikely to spot them doing the damage during the day. To diagnose if this is earwig damage, place a pot loosely stuffed with straw or shredded paper upside down at the base of the tree. Earwigs will hide in the pot during the day so you should find them there in the morning. If you do find earwigs you can either keep emptying the pot each day and destroy them, or spray them with an insecticide at dusk when they are active, or spread ant powder around the affected area. Although earwigs can be a pain they are actually beneficial to the garden too! They eat small insects and eggs so are a good natural pest control.

Sawfly larvae are also active between mid-spring and the autumn. You can remove them by hand or for heavy infestations you can spray with a chemical spray which will be available at all good garden centres (the label should guide you as to which pests it is effective against). You could also use parasitic nematodes if you prefer to garden organically. Best of luck Jackie, hopefully you will find the culprits so you can decide the best course of treatment. Let us know if you need any further help.

Name: Pauline Irvine

Question: Do I need to lift my Gladiloi for the winter, and if so when should I lift them I have 2 that have only just flowered?

Answer: Hi Pauline, how lovely to have flowers this late in the year! In milder areas Gladioli can be left in the ground over winter but they do require good drainage. If you have light, free-draining soil you can simply add a dry mulch of bark chips or leaves to the soil surface to protect the corms from the worst of the winter weather. If you live in a colder part of the country or your soil is heavy then corms are best lifted for the winter. Wait until the foliage dies down, then lift the corms and brush off any excess soil. Dry them on a tray in a well ventilated area for 2 weeks before storing them somewhere cool but frost-free for the winter. You can re-plant them from April onwards.

Name: Vicki Martin

Question: I have some young strawberry plants I've made from runners, and some new raised bed frames which I hope to make up and fill with new topsoil in the next week or so. Would you plant out the strawberry plants now, or over winter them in pots and plant in the spring?

Answer: Hi Vicki, strawberry plants are fully hardy so I would plant them out now. If the soil is still warm enough this will give the strawberry plants some time to establish new roots, resulting in better growth next spring!

Name: Louise Rowley-Spendlove

Question: Question about Dahlias. 1/2 are in the ground and the rest in a massive pot and all still with loads of foliage and flower. So what do i need to do to keep them for next year? I dont have a greenhouse but do have a garage but not convinced its frost free.

Answer: Hello Louise, it has been quite a mild autumn this year so plants are not dying back as quickly as usual. Wait until the frosts blacken the flowers and foliage before lifting the tubers out of the ground. Trim away the old stems to 5cm above the tuber. Clean off any remaining soil and if the tubers are wet, place them upside-down somewhere cool but frost-free for a few weeks to dry off.

You can then put the tubers into trays of dry sand, wood shavings or wrap them loosely in newspaper and store them somewhere cool but frost-free for the winter. Your garage is the perfect place to store the tubers - you can always place the trays of tubers into a cardboard box for further insulation if you’re concerned about the temperatures. It’s a good idea to check the tubers occasionally just in case one has started rotting, as this could spoil the other s. You can re-plant your tubers next May or June. I hope this helps Louise.

Name: Daniel Stewart Marshall

Question: Hi Sue, I have loads of white fly on my spring cabbages. It seems they are hard to get rid of, do you have any tips? Also, is there a chance any survivors will also move onto all next years brassicas? Thanks

Answer: Hi Daniel, this is common problem when growing brassicas; unfortunately the thick waxy leaves are hard to wet with sprays so controlling them is difficult. Fortunately the whiteflies don’t do much damage to the plants and normally only infest the outer leaves, which can simply be removed, leaving the centre of the cabbage edible.

The only way to treat this problem is with repeat applications of a spray on the underside of the leaves. Chemical sprays will state on the bottle whether they are effective against whitefly but do check they are suitable for use on vegetables and follow the application instructions carefully. You can also use insecticidal soaps or organic sprays, which can be applied more often. You will need to be vigilant as the sprays won’t kill the whitefly eggs and they will continue to hatch. Use organic sprays every 5 days - it may take 3 or 4 applications to work. In dry weather you can also hang yellow sticky traps to catch the adults flying around! In future you could grow your cabbages under a fine-grade enviromesh which will prevent the pests reaching your cabbages. I hope this helps Daniel, good luck.

Name: Diane Wilson

Question: Hi Sue, could you recommend hedging that would be dense and fast growing but suitable for a narrow garden?

Answer: Hello Diane, popular fast-growing hedging plants such as Laurel, Holly, Beech and conifers get quite big so wouldn’t really be suitable for a small or narrow garden. You could try privet (Ligustrum), which is fast-growing and dense. Privet is very tolerant of pruning and will thrive in any garden situation; Golden Privet (Ligustrum ovalifolium ‘Aureum’) is an attractive yellow-leaved variety.

Other ideal plants for narrow hedges are unfortunately quite slow-growing. I would recommend Box (Buxus) or Yew (Taxus baccata); both are excellent evergreen hedging plants and will withstand regular pruning well. Berberis verruculosa or Berberis thunbergii are good for creating a narrow hedge; both have a nice display of spring flowers followed by berries in the autumn. Berberis verruculosa is evergreen whereas Berberis thunbergii is deciduous. Both reach an ultimate height of about 1.5m.

Cotoneaster simonsii is semi-evergreen and bears attractive scarlet berries in the autumn; it can reach an eventual height of 2.5m. You could also try Osmanthus delavayi which is evergreen and produces fragrant white flowers in April and May. Osmanthus can become tall if allowed but is quite slow growing and very tolerant of clipping so makes an ideal narrow hedge. I hope this gives you some ideas Diane, best of luck.

Name: Kay Rogers

Question: Hi Sue,not sure how or when to prune my Cornus or blueberries. Any help please

Answer: Hi Kay, a lot of species in the Cornus genus require little or no pruning but if you’re growing a shrub for its colourful winter stems, such as Cornus alba, Cornus sanguinea or Cornus stolonifera, then it’s best to hard-prune these in February or March. Cut all the stems back to within 2 or 3 buds of the base, or to a permanent framework if you prefer your plants to be a bit taller. It’s important to feed and mulch your plants with compost or well-rotted manure after doing this to compensate for the loss of wood. For advice on pruning your blueberries we have an excellent article along with a video at the following link /how-to-grow-blueberries.

Name: Karl Hyde

Question: Hi, when is the best time to prune Pyracantha to ensure there is still a good showing of berries? Thanks

Answer: Hi Karl, unfortunately Pyracantha will lose some berries or flowers regardless of the time of year it is pruned, but as with other evergreen shrubs they are generally best pruned in mid-spring. If you have very wayward shoots that need removing simply cut these out completely, back to where they join the main branch. If you want to do a general prune to reduce the size of the plant then cut shoots to within two or three leaves of the main branches. This will ensure that some older wood remains as Pyracantha flowers on wood that is one or more years old. Hopefully you will still get a get a good show of berries next year!

Name: Angela Smith

Question: Why have I got no cauliflowers from my cauliflower plants despite lots of foliage?

Answer: Hi Angela, how disappointing; there could be several reasons for this. Firstly I’d consider the conditions your cauliflowers have been growing in. Unfortunately cauliflowers can be a bit fussy and heads will fail to form if growing conditions have been difficult. Cauliflowers resent dry soil at any stage of growth and need constant watering if the weather is hot and sunny. They will also sulk if left to become root-bound in modules or pots for too long before planting out.

If neither of these things seems possible then lots of foliage can suggest that your soil is rich in nitrogen. Plants can put on lots of leafy growth at the expense of flowers when there is plenty of nitrogen available. Next year you could try feeding your cauliflowers with a balanced fertiliser and making sure you don’t use too much chicken manure or high-nitrogen fertiliser. Hopefully something here rings a bell Angela and you can resolve this for next year!

Name: Yvonne Neblett

Question: Why are the leaves on my tree peony (in container pot) going brown, even though I have fed same. How can I save it?

Answer: Hi Yvonne. Without a picture it’s very hard to say. Tree peonies are deciduous plants and they will naturally lose their leaves at this time of the year. New foliage will be produced in the spring. However, if you are concerned that there is something else the matter with your tree peony then it is well worth reviewing its growing conditions.

Firstly it’s worth noting that tree peonies can take a few years to settle in. Tree peonies are at their best in a sunny position and won’t do well in heavy 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 - peonies like moist soil, but it must be well drained. Large containers hold a greater volume of water in the soil and this can cause the soil to become too wet. If the container is too large for the plant then you may need to repot it into something smaller. You may also want to check that the peony is planted so that the grafted union sits at least 10cm (4") below the soil surface. 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. Finally, you may want to provide some winter protection this year to prevent the plant being damaged by cold, frosty weather. Although tree peonies are perfectly hardy, they are susceptible to winter damage while young, particularly when grown in a container. Hopefully something here will help you. Best of luck Yvonne.

Name: Anna Mason

Question:Can you tell me a good variety to grow for seedless Dessert Grapes? I have a vine a friend gave me in a huge container but the grapes are very sour, I would like to replace it with something plump juicy and edible. Also would it be ok grown against a fence where it doesn’t get Sun in afternoon?

Answer: Hello Anna. Grapes are best grown in a south facing position in order to take advantage of those long summer afternoons, so your intended planting position is not really ideal. You should also consider that grapevines can become very large and will grow for many years so they are best trained against a more permanent structure is less likely to need replacing in future years.

We offer the red dessert grape ‘Dornfelder’  which is a nice juicy variety and the green grape variety ‘Phoenix’ which are both suitable for growing outdoors in this country. Both are virtually seedless (they have such small seeds that you would not need to remove them). If you are hard pushed to find a better location for a full sized grapevine then you might want to consider the dwarf table grape ‘Moscato’. This little grape can be grown in the greenhouse or a sunny spot on the patio and won’t require such a large space as a traditional grapevine.

Name: Anna Mason

Question: I have had problems last year with Pansy plugs and a similar issue this autumn. I had very healthy plug plants form you last year but a lot of them just died. The little plants collapsed and when I went to check they just lifted away from the soil. Similarly I dug up some seedlings and popped in a pot of compost this autumn. 5 seedlings in a large pot. 3 flourished and two collapsed and again when I checked them they just lifted away from the soil.

Answer: This sounds very much like the type of damage caused by vine weevil larvae. Vine weevil is a particular problem in containerised plants. The adults chew notches out of the edges of leaves but the larvae are more damaging as they overwinter in the compost and eat at the roots. Try investigating the compost for little white grubs of about 1cm long.

You can control Vine weevil attacks by always ensuring that you use fresh compost. If you have some old compost from last season then spread it on the garden and buy yourself a brand new bag. The best way to control vine weevil is by biological means. Apply nematodes in the autumn and spring to destroy larvae, and during the summer months you can squash the adults - they are fast runners so you will need to be quick! Best of luck, Anna.

Name: Sarah Griffiths

Question: Hi, please can you give me some advice on the best apple and pear trees to grow in pots on my patio please, it is a south facing garden that gets very hot during the day. Thanks very much.

Answer: Hi Sarah. There are lots of miniature fruit trees that are suitable for your patio including plenty of patio apple trees and pear trees. This is really a question of your particular tastes and preferences, but I would suggest that you choose a tree that is grafted onto a dwarfing rootstock as this will make it better suited to growing in a container. One other thing to consider is whether that tree will be a self fertile variety - if not then it will need a pollination companion in order for fruit to set. However most of our patio fruit trees are self fertile so this should not cause you too much difficulty.

If you are struggling to choose just one tree then try one of our family fruit trees with more than one variety grafted onto them. Whatever you choose you will need to use a soil based compost such as John Innes No. 3 and make sure that you drill plenty of drainage holes into the bottom of the container. As it is a very hot position then you will need to be prepared to do a lot of watering or maybe set up an automatic irrigation system if necessary. Let us know how you get on Sarah.

Name: Angela Lee-Smith

Question: The last lot of daffodil bulbs bought from you were planted in a largish container they are coming up already, a bit early? Hope the snow when it comes doesn’t harm them.

Answer: Unfortunately the mild weather has confused your daffodils Angela! Don’t worry - this is perfectly normal (particularly if they were planted while the soil was still warm). Many bulbs put on a small amount of growth in the autumn, which is often fairly frost hardy and will over-winter quite happily. My Iris bulbs have started sprouting at home too!

Name: Jawahar Swaminathan

Question: I received a batch of tree lily bulbs today from T&M. The cultural instructions mention what to do if the bulbs were received September/October or February/April. The bulbs appear to be growing. What are your suggestions on how to deal with them in November? The weather is not frosty as yet down here in Cambs.

Answer: Hello Jawahar. In very cold areas Lilies can be grown in borders and lifted, cleaned and stored for the winter, but in mild areas most lilies should survive outdoors provided that the soil is not too wet. With that in mind you can either plant you Oriental lilies outdoors now in a moist, free draining soil or start them off in containers in a cold greenhouse, depending on your soil conditions and how hard the winters are in your area.

Prior to planting, add plenty of well rotted manure or garden compost to the soil to give your lilies the best start. If you are growing lilies in containers, use a loam based compost such as John Innes No.2. Lily bulbs should be planted at a depth of approximately 3 times their own height and 15cm (6") apart. Planting deeply helps to protect the bulb during particularly hot periods. Choose a sheltered, sunny position where lilies will grow with their heads in the sun and their roots in the shade. I hope that this helps you Jawahar.

Name: Tracey Williams

Question: I’m looking at planning some veggie growing for next year, but have limited space. I had a go at green beans last year. Could you advice me of green beans/ runner bean varieties that I can grow in pots or crates and carrots or any other veggies I can grow this way or any veggies you can grow in complete shade apart from herbs. Thank you in advance.

Answer: Beans are a great choice for containers! Try Runner Bean ‘Hestia’ - it’s a dwarf variety so it’s perfect for small spaces. If you like a splash of colour then I can certainly recommend Dwarf Bean ‘Purple Teepee’. I grew it myself this year and was astonished buy the quantity of beans that I harvested. I’ve often thought that ‘Borlotto’ might be interesting to grow too.

Carrots do very well in containers particularly the round types such as Carrot ‘Parmex’ and the quick growing varieties like Carrot ‘Mignon’.

You can certainly grow vegetables in partial shade. Some plants actually crop better with some shade from intense heat and sunlight. You can grow cool-season crops such as peas, radishes, lettuce, salad leaves and spinach. You could also try herbs such as parsley, chervil and chives, which will all grow happily in shadier conditions.

Name: Belinda Estell

Question: I have a tree peony; it's only 2ft high at the moment. I'd like to move it, when is the best time to do this?

Answer: You can move your tree peony now before the winter weather sets in, or leave it until the spring if you prefer. When you do move it, try to lift as much of the rootball as possible to reduce root disturbance, as peonies are slow to establish and resent root disturbance. Take care to replant your tree peony so that the grafted union sits at least 10cm (4") below the soil surface as shallow planting may also hinder establishment and delay flowering. Best of luck Belinda.

Name: Julie Atkinson

Question: I brought my potted olive tree indoors last month. It has produced lots of flowers which are now turning to little buds - is there any chance these will make it to fully grown olives in the UK if it remains indoors? I didn't buy it for olives anyway, just like the trees, but olives would be a bonus! Thanks

Answer: How exciting!! Most Olives are self fertile so there is a good chance that the flowers were successfully pollinated. If you keep the tree indoors over the winter and move it back outside next summer then there is a good chance that they may ripen. Olives require long, hot summers for the fruits to ripen properly so try to ensure that it stands in a sunny south facing position next summer and hopefully by next autumn they will be almost ready to harvest.