Thompson & Morgan Facebook Q&A Session 4th March - Your horticultural questions answered.

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Name: Calum Wiley

Question:Hi Sue & T&M, I've received my 3 hardy orchid bulbs today, but the instructions don't tell you to plant them. They have green/white shoot on each bulb, so I've planted them in 3 4inch pots with the shoot 1/2 way above the compost. Please can you tell me if this correct or should be shoots be beneath the compost?

Answer: Hi Calum. Your hardy orchid tubers will be very small (about the size of a peanut) so they will only need a very small pot. You can either pot all of them together in a 7.5cm (3") or pot them individually in 5cm (2") pots. The tubers should be planted in specialist orchid compost at approximately 2.5cm (1") deep, so you may need to carefully exhume yours and repot them slightly deeper than they are at present.

Until you see the shoots above ground you should keep the compost just moist. Once the shoots appear above ground you can increase watering and give them an occasional feed. Grow them on a windowsill or in a cool greenhouse provided that they are protected from strong sunlight at all times. After flowering, decrease watering as the foliage dies back. Move the tubers to a cool position over winter (0° to 5°C, or 32° to 41°F) and keep the compost barely moist until new shoots appear the following spring. Hope that helps Calum.

Name: Becky Whitehead

Question: Hi sue i planted my lily tree bulbs in November last year. When are they likely to start sprouting, no sign yet. So i am starting to think i have done something wrong!

Answer: It’s still very early Becky, so don’t worry just yet. You may not see any growth from your tree lilies for another month until it warms up a bit. If you still see no growth by mid May then you could gently scrape back some of the compost to investigate, but I doubt that you will need to wait this long.

Name: Yvette Britton

Question: Hi Sue,I moved a medium sized (10' tall) Myrtus Communis 'tree' in the Summer and it has been hit hard by frosts here in Cornwall - down to -8 for a few nights in a row, on 2 occasions + other less severe frosts. The leaves are nearly all brown and crispy. Will it recover or is there anything I can do to help it?

Answer: What a shame Yvette. It rather sounds as though your Myrtle has died. The best way to check is to scrape a tiny bit of bark back on the main stems with your thumbnail. If the stem is green beneath then it is still alive.

If you do find that some stems are alive then give it a good mulch of well rotted manure or compost (take care not to mound it up around the stem). Wait until late spring before you begin to prune out any dead wood and keep it well watered this summer while it’s new root system is developing. It will take a year or two to fully settle into its new home.

Name: Mary O' Donovan

Question: When is the best time to plant gladoli corms and crocosmia bulbs!

Answer: Hi Mary. Gladioli can be planted any time from now until mid summer. If you plant them at two week intervals you will get a continuous display!

The crocosmia corms can be planted in late spring at about 10cm (4") deep. So you have plenty of time yet, Mary!

Name: Diana Hills

Question: Hi Sue, I am looking for shrubs to go into a north facing border that will produce pollen/ flowers for bees in spring or summer, and also berries in winter for the birds any ideas please. Thank you.

Answer: Cotoneaster is ideal as it’s spring flowers are attractive to bees and other insects, and it’s autumn berries are eaten by several bird species. Chaenomeles, Symphoricarpus and Pyracantha are also attractive to both birds and bees.

Leycesteria and Holly also produces berries that attract birds (although you will need to make sure that you have a female holly with a male nearby to pollinate), and Sarcococca provides a good source of winter berries when there is little else for birds to eat.

You might also consider under planting with nectar rich herbaceous plants such as Heuchera or Pulmonaria which provides valuable spring flowers for bees. All of the plants mentioned here are suitable for a shady or semi-shady position. Hope that gives you a few ideas Diana.

Name: Janet Howie

Question: Hi! I have to move home and therefore would like to take my fave fruit and flowers with me... Eg peonies delphiniums agapanthus kiwi raspberries blackcurrants blueberries comfrey hollyhock gooseberries strawberries dicentra wisteria Daphne ...etc etc... Any advice? I plan to dig up and pot then hopefully replant at my new house or leave in pots if nec! Timing? Medium? Feed? Thanks, Jan xxx

Answer: Hi Jan. Now is the time to do it, before the plants start into active growth. To take the herbaceous perennials, simply dig them up, shake off most of the soil, and divide the bareroots into portions. Discard the old woody portions and pot up the young, healthy portions using good quality compost such as John Innes No.2. They won’t need feeding as the fresh compost will contain plenty of nutrients for the time being.

The fruit bushes should also be lifted now. Make sure that you take as big a root ball as possible to minimise root disturbance. Pot them into containers using your own garden soil or John Innes No.3. When you get to your new garden, take time to improve and prepare the soil properly before planting them out again. If the summer is rapidly approaching then you may want to wait until autumn before planting them out again. They will be in their containers for a season so long as you keep them well watered. You may find that you will lose this year’s crop or have a reduced crop, but once they are settle in normal crop production should resume.

Name: Anna Simon

Question: How do I know when potatoes have 'finished' chitting and are ready for planting out? How long do they usually take? Mine have been in the shed for a fortnight now and don't seem to be doing much!

Answer: Hi Anna. Make sure that your potatoes are chitting in a frost free position in natural light. I tend to put mine on a north facing windowsill indoors. Chitting normally takes around six weeks or so and sturdy 'chits' should attain up to 25mm (1") in length.

Planting them will depend greatly on the weather and what type of potatoes you are growing. For example, first earlies can be planted from the end of February but if the ground is frozen or very wet then you will need to delay until conditions improve. Why not take a look at our potato growing guide. This should be able to answer many of your questions.

Name: Bill Holder

Question: Hello Sue, I have just bought a very nice phalaenopsis orchid that is a massive one thats sitting 1m high, ive been looking at so many peoples views on how to water and keep the plant healthy. I bought one nearly a week ago, most advice is ...going on that you should let the plant almost go dry before watering it. Someone also said stick you finger in pot and if dry then needs water. Other person said if the roots have gone from green to silver colour then time to water. Im guessing this is all right, now the right type of water do I use? Most say rain water is best, now I have rain water but brown colour from water butt, will this affect the plant?, some says room temp filtered water thats been left out all night on side and everyone is saying water in morning. I do have hard water where I live to. Last of all feeding it, is baby bio orchid feed?, it says on bottle to feed everytime I water, is this right? as garden center said once a month and some say on feed in spring/summer not winter. Im sorry I might sound like im going on here, but ive managed to kill off all my supermarket bought ones and this one cost me £30 and looks so nice. I hope you can help here. Thanks.

Answer: That’s a long question Bill! It sounds as though you are on the right tracks though. Phalenopsis is an epiphytic orchid that enjoys warm temperatures. While your plant is in active growth from spring to autumn you should be watering it with soft water or rainwater to keep the compost continually moist but not waterlogged. Don’t worry about the colour of your rainwater - the main point is that it doesn’t contain chlorine or lime. In winter you can reduce watering and allow the compost to almost dry out between waterings. The idea is to keep the roots dry but still provide a little water to prevent the plant becoming dehydrated.

From spring to summer, feed your phalenopsis every three weeks (once a month will be fine if this is easier to remember). Use a specialist orchid fertiliser. Alternatively use an ordinary balanced liquid feed diluted to a ¼ strength solution. You do not need to feed the plant during the winter months while it is not in active growth.

Two final things to remember are that your orchid will need a warm position in bright, filtered light throughout the year. Remember that positions close to heaters or radiators should be avoided as these create very dry air, and direct strong sunlight can also be damaging. Also during the summer you should mist your phalenopsis at least once a day to increase humidity around the leaves. There is no need to mist in winter however.

These plants are really quite specialist, but if you can find the ideal position for your orchid then the rest is just a matter of good care and attention. Good luck, Bill.

Name: Rachel Ferris

Question: Hi Sue, We have a Wisteria in a pot, the pot seems quite small for the tree now. I would like to move it to the garden and let it grow up the side of a trellis as some of it didnt flower last year or grow new leaves as it did the previous year. Should i move a Wisteria? and if so, when's the best time of year? How to i go about moving it and caring for it once moved? We have clay soil in the garden.Thanks x

Answer: Hi Rachel. You can certainly move your Wisteria - between now and mid-March is the ideal time to do this (it’s best to move trees and shrubs whilst they are still dormant). Although Wisterias will grow well in clay soil I would prepare the soil first by digging in a good 5-10cm layer of organic matter (well rotted manure, compost or recycled green waste are all good). Before you transplant it, I would recommend that you prepare some heavy duty supports for the twining stems. It may not look very big at the moment but in time Wisteria can reach up to 9m (28’) and it is much easier to put suitable supports in place now than to do it later when the stems have become woody.

Make sure you water the plant thoroughly before transplanting it. I’m assuming your Wisteria has been in its pot for some time so it may be a bit root-bound! Gently tease out the roots if you can, you may find this easier with a hand fork. Cut off any broken roots with secateurs. Dig a hole and place the plant so it is at the same level it was in the container, taking care not to plant too deeply as this may cause the trunk to rot. Backfill around the roots with soil and gently firm in, making sure there aren’t any big air pockets remaining. It’s a good idea to mulch around the base of your Wisteria to help it retain moisture this summer and suppress weeds. Make sure you leave a little collar of about 10cm (4 inches) free of mulch around the trunk of your Wisteria to prevent the bark rotting.

Once you’ve completed the task it’s just a case of letting the Wisteria settle in. Keep the soil moist this summer, especially if we get long periods of sunny weather. If you need to carry out any pruning, wait until next year to give your Wisteria time to recover. Good luck Rachel.

Name: Daniel Stewart Marshall

Question: Hi Sue, I am growing both autumn and summer fruiting raspberries in a border about a foot wide. They are planted a foot and a half apart. All the plants are growing a lot of new canes. Do I let them all grow or is best to get rid of some and if so how many do I keep for each plant? Thanks x

Answer: Hi Daniel. You need to treat the summer ones slightly differently to the autumn ones. Prune all of your autumn fruiting raspberry canes to ground level now.

The summer ones should have their stems loosely tied in to their support wires as they grow. In autumn, prune the canes which have fruited over summer to ground level. Canes which have not fruited should be ‘tied in’ to their supports. Aim to have 6 to 8 fruiting canes per plant.

For both spring fruiting and autumn fruiting varieties you can apply a mulch of well rotted manure or garden compost to the base of the canes in spring. This will help to retain moisture throughout the summer.

Name: Anna Mason

Question: Lost all my little pansy plug plants and I suspect Botrytis now some of my Pansies in containers seem to have Mould on the flowers as well ummh err Help. MANY THANKS!

Answer: Oh dear Anna, what a shame. If it is confined to just a few plants then destroy those affected by burning them or putting them in your household waste bin - do not add them to the compost heap! It is still very early in the season, so there is time to order some more pansies. The remaining plants can be sprayed on a dry day with a fungicide that is suitable for use on ornamentals.

Many fungal problems can be reduced by good hygienic cultivation practices. Water the plants from beneath the foliage rather than over the top, as this may cause the plant to rot and also creates ideal conditions for the spread of fungal spores. Don’t crowd the plants too closely together - the better the ventilation, the less the risk of fungal infection. Also, remove and destroy any infected plant material as soon as you spot it. Finally, use fresh, sterilised compost when potting up plugs and before reusing pots then they should be thoroughly washed clean.

Name: Gill Le Fevre

Question: Hi Sue, lots of questions: 1. I've propagated shrubs via cuttings last autumn and now have lots of mini plants growing. What do I do next? When should I plant them out or should I pot them on first? 2. Is it too late to replant strawberries... in the spring or will that reduce the fruit I get? 3. what plants would you recommend for growing at the base of a tree? 4. when is the right time of year to prune St John's Wort / hidcote and how hard can it be cut back? 5. what plants would you recommend to grow along a garden fence, to prevent weeds from growing under from next door? Many thanks!

Answer: Hi Gill. I would pot on your young shrubs into their own containers to grow them on this summer before planting them out in autumn or next spring. Use a good quality compost such as John Innes no.3.

Now is an ideal time to move your strawberry plants and this won’t have any detrimental effects to the plants or your crop. Dig some organic matter and a slow release fertiliser into the soil where you will be planting the strawberries. Make sure you remove as much of the root ball as you can when moving the plants and water them in thoroughly once transplanted. This should get them off to a good start!

Many plants find it tough to compete with the roots of a tree although bulbs will normally do well. Cyclamen thrive in the conditions underneath trees and shrubs, enjoying the dry soil throughout the summer; they will brighten up the base of your tree when planted en mass. You could also try Bluebells, Snowdrops, Crocus and Lily of the Valley. Hostas tend to do well at the base of trees and thrive in the shade that the canopy provides. Hardy Geraniums (Cranesbill) and Periwinkle (Vinca) are also of woodland origin so will do well at the base of a tree.

Pruning a St John’s Wort (Hypericum) can vary depending on the species you’re growing. ‘Hidcote’ should be pruned in the spring, removing any weak, old or thin growth. Shorten the remaining stems back to the base or to strong shoots. Always make your cut just above a bud. If your plant has got out of hand you can prune all the stems to ground level now - you will probably get quite vigorous new growth in response!

Unfortunately there are few plants which will stop weeds creeping under the fence, particularly if they are persistent and vigorous perennial weeds like stinging nettles, brambles and bindweed. You might try to dig down under the fence (about 30cm deep) and place a barrier between yours and your neighbour’s garden, using a material such as weed suppression fabric (available at most garden centres), but this is unlikely to prevent them coming through on your side. Dense evergreen shrubs planted along the fenceline would ultimately block out the light source and discourage the weeds; however persistent weeds such as bindweed will simply use your shrubs as climbing frames!Unfortunately all that you can really do is to attack the weeds as you see them appear and try to keep on top of them. You could always politely ask your neighbour if they could remove them, or even volunteer to do this for them!

Name: Sandra Marshall

Question: Hi Sue, I have a wisteria which I planted about 5 years ago, the plant is growing very well up the side of the house, unfortunately the flowers are a very pale lilac, is there any way I can get the blossom to be a deeper shade? Thanks

Answer: Hi Sandra, the colours of the flowers on your Wisteria are determined by the variety you grow. Wisterias can flower in shades of mauve, blue, white or pink depending on the species and cultivar. Unfortunately there is no way to achieve a deeper flower colour. Make sure you mulch around the base of your Wisteria now to provide it with nutrients throughout the growing season and to keep it in tip-top condition.

Name: Natalya Boyd

Question: Hi Sue, I would like to try tomato and cucumber grafting this year. Please could you advise the best varieties to use as rootstock for each of these plants? Thank you.

Answer: Hi Natalya, this is an interesting subject area! Rootstocks are normally chosen for their vigour and resistance to soil-borne pests and diseases such as fusarium, verticillium wilt and the root-knot nematode. Grafting is mainly used to improve vigour and disease resistance on plants which naturally have neither of these qualities.

 

A classic example is heritage tomatoes which may not have the vigour or disease resistances of modern cultivars. Many modern cultivars have been bred to have natural disease resistance; strong growth and heavy cropping (so do not need to be grafted). A good example of this is ‘Falcorosso’, which is an excellent tomato in its own right but would also make a good rootstock due to its disease resistance. Another good variety to try would be ‘Ferline’ which is a vigorous plant with resistance to fusarium and verticillium wilt.

 

For cucumbers you can experiment with using gourds, squashes and pumpkins as rootstocks as they are all closely related. If you would like a cucumber rootstock try using ‘Flamingo’  for its vigour and disease resistance.Good luck Natalya, we’d be very interested in hearing the results of your grafting!