Facebook Q&A Session 21st March 2014

Thompson & Morgan Facebook Q&A session 21st March 2014
- your horticultural questions answered.

Thompson & Morgan Facebook Q&A session 21st March 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.


"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.


"This may be a really stupid question but I'm not sure what they are. I planted thousands of poppy seeds last year, are these young poppy plants or stinging nettles coming through?"

Sue - T&M
Horticultural Expert

Hello Clare, don’t worry these definitely aren’t stinging nettles. They look like Honesty (Lunaria annua), a hardy biennial plant which makes a rosette of leaves in the summer and autumn before flowering in the spring. Much like forget-me-nots, they have a weedy nature but are often cultivated in gardens for their colourful show of spring flowers. Honesty also has attractive flattened seed pods which look like coins, and the flowers are an excellent source of nectar for early butterflies. The largest plants in your photo will probably flower this spring. I hope this helps.


Annie Polgara (first timer question)

"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.


"I emptied a large compost bin which had top soil - however I did not find any worms. Does this mean the soil is unhealthy?"

Sue - T&M
Horticultural Expert

Hi Santosh, this is nothing to worry about. Worms will only be present in soil if there is a supply of organic matter for them to eat, such as dead leaves, decaying plant material or manure. I’m also not sure if your compost bin is sitting on the ground with easy access for worms or whether it is raised up on feet. The soil in the compost bin could have lacked organic matter or it may have become too saturated with water or too dry for worms to be happy. Also if it has been in there for a while there could be a lack of oxygen in the soil. Once the topsoil is spread back out in the open many creatures should start to inhabit it again. You can help improve your soil by digging in lots of organic matter such as well rotted manure or compost. I hope this helps.


"Hi, we have a small garden, in one corner the soil is always wet and never gets direct sunlight, would like to plant a tall shrub to fill the corner, or anything, any recommendations. Thank you. Eva x"

Sue - T&M
Horticultural Expert

Hi Eva, lots of people have these trouble spots in their gardens caused by buildings, fences and trees. You could try Mahonia, which grows very well in full shade and produces highly fragrant yellow flowers in the winter and spring. Other tall shrubs for damp shade include Viburnum, Eleagnus x ebbingei, Aucuba and Holly. Daphne laureola and Daphne pontica are nice evergreen shrubs with fragrant green spring flowers although they only grow to around 1 metre. There are also many perennials which tolerate or prefer shade such as Euphorbia amygdaloides which is a lovely plant for structure and fresh green colours, although take care if you have children or pets as it is poisonous. Hardy Geraniums are good groundcover in the shade producing flowers in early summer though to autumn - Geranium phaeum is particularly tolerant of heavy shade. Vinca (periwinkle), Epimedium, Brunnera, Hosta, Pulmonaria and Tiarella cordifolia (Foam Flower) will also do well in damp shady conditions. For more plants for damp shade take a look at our 'Plants for shade' article. I hope this gives you some ideas Eva, good luck.


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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