Facebook Q&A Session 19th August 2014

Growing Assistance
- your horticultural questions answered.

View the answers to our previous sessions.


"Hi Sue, is there a rule of thumb re sowing seeds? Do we use seed trays and 'prick out' or cells then pot on? Also do I need to Vermiculite or just use the compost to cover? Thank you"

Sue - T&M
Horticultural Expert

Hi Cat. This is a great question - with a simple answer. If you are dealing with larger, quick growing seeds such as Sunflower, Sweet Pea, Marigold, and Calendula for example, then you can get away with sowing them straight into cells in late spring and early summer. Because these seeds germinate and grow quickly, then they will need the space provided by a cell much sooner than smaller seeds would, and they will not be at such a risk of rotting.

Most other seed will be best started in seed trays. Many need light to germinate so it is important to read the sowing instructions carefully. As a rule of thumb however, you can cover the seed with a sprinkling of vermiculite that is roughly equal to the depth of the seed, i.e larger seed can have a good sprinkling, while very tiny seed probably won’t need any at all. I hope that makes sense to you. I would always recommend following the sowing instructions as some seed do have very particular requirements.


"How do I encourage next year's growth on your illumination pink foxgloves?"

Sue - T&M
Horticultural Expert

Hi Michael. The best way to ensure a great display next year is to keep your plants in tip top condition. Water foxglove plants regularly during particularly hot periods. They will also appreciate the occasional feed of a balanced fertiliser this summer. Throughout the growing season you can deadhead any faded flowers to promote more flower production this summer.

In autumn, cut back any remaining old flower stems to encourage plenty of new side shoots. Although Foxglove 'Illumination Pink' is hardy in mild parts of the UK, I would recommend that you move any that are in containers to a position with a minimum temperature of 0°C (32°F), and water sparingly during the winter months. Border-grown plants can be lifted in autumn and potted up for over-wintering. Better safe than sorry! I hope that helps.


"I am going to try to grow rainbow eucalyptus as bonsai, do they need any special food or temperatures?"

Sue - T&M
Horticultural Expert

Hello Claire. This is quite a specialist question - and I am certainly not a Bonsai expert (although it is an absolutely fascinating science!). However, I can tell you that Eucalyptus is not a particularly easy Bonsai as it is such a fast growing tree by nature. Don't try to make it too small - I would suggest that you aim for a height of around 3ft. You will need to keep on top of the new growth as it will be produced rapidly and will need lots of pinching out.

You will need to use a fairly light sandy soil mixed with plenty of organic matter, and it will require frequent watering, especially during root establishment. Once it is established then a monthly feed with a balanced Bonsai fertiliser will be appreciated. It will enjoy a sunny position outdoors during the summer months. Rainbow Eucalyptus is not frost hardy so it will need to be brought into a frost free greenhouse or conservatory during the colder months of the year. Avoid putting it into a warm room indoors though as this will produce weak, spindly growth.

There are some superb Bonsai nurseries in the UK who I'm certain would be able to give you more specific information about how to grow these fabulous trees. Best of luck with it, Claire.


"In our school gardens we created a Pumpkin Patch. Went away for 2 weeks holiday and now it's more like a Pumpkin explosion. The plants are huge with runners going very where. Any advice on how to look after these monster plants? Should we cut them back or limit the number of Pumpkins to 1 per plant for example?"

Sue - T&M
Horticultural Expert

"Hi Andy. Yes they do travel! Pumpkins will begin to produce long stems which can be trained in a circle around the plant to prevent them spreading too far. There's no need to limit the fruits unless you are planning to grow giant pumpkins!

You will need to feed and water your pumpkins regularly. When growing pumpkins, a thick mulch of organic matter spread around the plants will help to conserve moisture at the roots. If possible, hoe between the plants regularly to prevent weeds from establishing.

Leave the pumpkins on the plant for as long as possible until the skin has hardened and the fruits start to crack near to the stem. You will need to harvest the pumpkins before the first frosts by cutting each fruit from the stem leaving several inches of the stem attached. Take a look at this article for more information on growing Pumpkins."


"What's the best way to prune Pyracantha, to keep it within its boundaries, and keeping as many flowers and future berries as possible? Thanks!"

Sue - T&M
Horticultural Expert

"Hi Nathan, now is the time to prune your Pyracantha but it will mean that you will lose some of the flowers and berries – there is really no way to avoid this. Bear in mind that it flowers and fruits on two year old wood so the more of this that you can retain, the better.

If the plant is a free standing specimen then simply remove any wayward branches completely to reduce its size. If you are growing a wall trained Pyracantha, start by cutting back outward growing shoots and then shorten the remaining shoots to fit the space available. Make sure that you use clean, sharp secateurs to reduce the risk of Fireblight."


"Should you take the runners off raspberry plants and if transplanted do they stay true to parent plant?"

Sue - T&M
Horticultural Expert

"Hello Jean. Yes it's a good idea to remove Raspberry suckers to keep the plants with their allotted space. If you would like to use them elsewhere in the garden, or share them with a neighbour, then they can certainly be potted up and they will be true to the parent plant. When you remove the suckers try to dig down a little and get some roots. These can then be potted up at the same depth that they were growing in the ground. It's really that simple!"


"I also have brought a Yellow Gooseberry from T&M; how do I plant it as I have never had one before. Thank you"

Sue - T&M
Horticultural Expert

"Hi Ann. Planting bareroot gooseberries is fairly straightforward. Here is a short video to help you."


"In the school gardens we don't have room to plant potatoes in our beds. We are going to use Potato growing bags. Our compost bins are still too young to produce any compost as yet so can you advise what is the best compost to use? Also a sneaky second question - can we companion" plant potatoes with anything? Many thanks in advance."

Sue - T&M
Horticultural Expert

"Hello Andy, a good quality multi-purpose compost is best to use for growing potatoes in containers. The light, airy structure is perfect for easy root growth and tuber formation. When growing potatoes in bags and containers it's best to feed them every other week with a balanced liquid fertiliser or work in some slow-release potato fertiliser before planting for the highest tuber production. Ordinary multi-purpose compost generally only has enough nutrients to keep plants happy for 6 weeks.

With regards to companion planting, I can't recall any specific companion plants for potatoes as they mainly suffer from fungal and bacterial diseases. However, the principle of growing herbs, and encouraging insects and birds into the garden is still a good one to follow as it encourages a healthy garden. Take a look at our Companion Planting Guide for some ideas. You could even grow mint as an accompaniment to the finished crops! I hope this gives you some ideas Andy, best of luck."


"I sowed sweet peas into those cardboard like pots (tiny) and they have grown really big - do I leave them in the cardboard pots when I re-pot them and how big a pot do I pot them up into? When can they go into the garden?"

Sue - T&M
Horticultural Expert

"Hi Annie, in theory you are supposed to be able to leave plants in cardboard (or coir fibre or peat) pots and roots should grow through. However this isn't always successful and the cardboard can become a barrier to the roots, resulting in slow growth. You could either completely remove the plants from their pots and re-pot them or make sure the bottom of the cardboard pot is removed to allow for root growth. Tearing away the top of the pot will also help, or planting deeply enough that the top is completely below soil level. Wetting the pot will make tearing easier.

Sweet peas are normally sown in deep pots as they are deep rooting and then planted straight out into the garden once ready. To pot up into bigger containers, choose a pot which is about 5cm (2") bigger in diameter than the original pots. To stop your sweet peas falling over or becoming tangled its good practise to pinch them out just above a set of leaves to promote bushier growth. This will also delay growth if the weather is unfavourable for planting. Sweet peas are hardy annuals so can be planted out from mid to late spring once the weather has reliably started to warm up. If they've been raised indoors in a warm environment then its best to harden them off for a week by putting them outside during the day and bringing them in at night. If we are still having regular frosts then wait until milder weather before planting out. You can find out more about growing sweet peas with our 'How to grow sweet peas' guide. I hope this helps Annie, let us know how you get on."


"When is the best time of Autumn to cut back / prune my apple & cherry trees. Also how far from the branch - meaning the minimum of branch left. They are not OLD TREES 5yrs, still small girth. I want to prune hard as the rain this year has made thin branches & Apple Tree top bent over branches @ top. Also what's the latest I can buy from T&M; a very sweet Apple tree this year, I will also have a Pear tree from T&M; this yr. approx November delivered. Sincere thanks."

Sue - T&M
Horticultural Expert

"Hello Ann. Your apple tree is best pruned during the winter months. Begin by removing any dead, diseased or misplaced branches entirely. Does your apple only produce fruit at its tips? If so then it is probably a tip bearer and so you will only need to shorten the main branches by a quarter of the previous season's growth. The laterals can be left unpruned.

If your apple produces fruit from spurs further down the branch then you can shorten the main branches by a quarter of the previous season's growth. The laterals can be cut back to 5 buds from where they join the main branches.

Regarding your Cherry tree, you should avoid winter pruning as this leaves cherry trees prone to silver leaf disease. Established cherry trees with a decent framework should require only occasional pruning to remove damaged, badly placed or diseased wood, and to shorten strong growing laterals by half.If you are planning to order some more fruit for delivery this autumn then I would recommend that you place your order early to avoid disappointment."


"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

"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. "


"I have some Kleim's Hardy Gardenias; this will be year 4 and still no flowers. Do feed every summer when feeding pots. How can I get them to flower? Kept in cold greenhouse first 2 winters but outside for last 2."

Sue - T&M
Horticultural Expert

Hi Julie, Gardenias originate from open woodlands and savannah in tropical or subtropical areas of the world and as such do like to have plenty of light and warmth, even in the winter, as they are evergreen. Placing them in a relatively sunny position throughout the summer should help to stimulate flowering. It is often recommended that indoor Gardenias are shaded from direct sunlight, but outdoors Gardenias are growing in a much cooler environment and need all the warmth they can get. Over winter, a cool greenhouse or conservatory will be appreciated to offer a little protection. It's also worth having a look at the fertiliser you're using. A fertiliser with a high nitrogen content can encourage leaf growth at the expense of flowers - try using a high potash fertiliser. One other thing to consider is that any check to growth, such as drought conditions, can prevent flower buds forming or abort those which have already started to form. Make sure the compost stays relatively moist, particularly during hot weather to give your Gardenias the best growing conditions possible. I hope this helps Julie, let us know how you get on.


Sue Sanderson T&M horticulturalist

About Sue Sanderson

Plants and gardens have always been a big part of my life. I can remember helping my Dad to prick out seedlings, even before I could see over the top of the potting bench. As an adult, I trained at Writtle College where I received my degree, BSc. (Hons) Horticulture. After working in a specialist plantsman's nursery, and later, as a consulting arboriculturalist, I joined Thompson & Morgan in 2008. Initially looking after the grounds and coordinating the plant trials, I now support the web team offering horticultural advice online.

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