Thompson & Morgan Facebook Q&A Session 16th September - Your horticultural questions answered.

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Name: John Fowell

Question: If I was to grow moss on the top of my hanging baskets, and then plant plugs in them through it, would it work? Would the moss help retain moisture? Would you need to feed much more? Cheers. John

Answer: Hi John. Moss will use water from the compost surface (moss doesn’t have a root system as such) so you would need to keep it constantly moist, which could be time-consuming and may not suit the plants in your hanging basket! Moss does use a small amount of nutrients from the soil surface but shouldn’t affect the amount you need to feed your plants. You would find that once your plants grew they would smother the moss and it would die from lack of light and competition. You would find a layer of pebbles or stones much more effective at retaining water in your hanging baskets. I hope this helps John.

Name: Lucy Garden

Question: A question for Sue's next session please - a friend has a leggy rhododendron that she says she's neglected, but she's nervous about pruning it - can you help? What time of year should she do it? She lives in Aberdeen. My friend says its lower leaves go yellow and drop off, and that it looks sick - but it has lots of flower buds. She plans to give it some extra ericaceous soil and maybe feed it.

Answer: Hi Lucy, yellowing leaves are often a sign of nutrient deficiency although leaf drop can occur after periods of drought or water logging. The Rhododendron may also be unhappy if growing in an alkaline soil - it might be worth purchasing a simple soil testing kit to find out the pH of the soil.

It’s also not uncommon for older Rhododendron specimens to become naturally bare lower down on their branches. As growth seems to be limited to the top of the shrub it’s probably best to undertake some drastic pruning to encourage leaves to grow further down. Many Rhododendrons respond well to being cut back hard although without knowing the specific type your friend has it may be best to cut back in stages to prevent shocking the plant.

Pruning should be carried out just after flowering, either in late spring or early summer. I would recommend firstly cutting out any dead, damaged or diseased branches. To renovate, cut up to half of the main stems almost to ground level. All remaining stems can be cut down to about half their height or to an appropriate side shoot or healthy-looking bud. It’s very important to feed and mulch the Rhododendron after this kind of work is carried out. Use a special ericaceous feed - you could use a liquid feed or a slow-release fertiliser. After feeding, mulch around the base of the Rhododendron with well-rotted manure or ericaceous compost.

The year after pruning you should hopefully see some vigorous new growth at the base of the plant. You can remove some of these new shoots if they are overcrowding each other. The remaining older branches can then be cut back completely or shortened to form a pleasing framework. This may seem drastic and a little scary given the size of the shrub but it is unlikely to sprout new leaves from the current old wood. Once the shrub regains its vigour it is worth giving it a light prune each year after flowering to maintain a good shape. Good luck Lucy, let us know how you get on.

Name: Catherine Johnson

Question: Picked the last of the runner beans and tomatoes. Can anyone help me as to why all my butternut squash have failed? I got perfect little green 1 inch long fruits that then wrinkle up and turn yellow and fall off- haven't had a single success this year :(

Answer: Hi Catherine, it sounds as though your squash fruits weren’t sufficiently pollinated. Female squash flowers have a baby fruit just below them, which when pollinated successfully, begins to swell and change colour. If not pollinated, they will shrivel and fall off. Normally insects will pollinate the flowers for you but if you’re having trouble you can always pollinate the flowers by hand to ensure the fruits set. You’ll need to wait until male and female flower are open at the same time (females have the baby fruit behind them, males just have a thin stem). Use a soft paintbrush to pick up pollen from the male flowers and gently but thoroughly brush this on to the stigma of the female flower (the long stem arising from the centre of the flower). You can also pick the male flower off completely and just rub the pollen directly on to the stigma. I hope this helps and that you have better luck next time!

Name: Leigh Arthur

Question: What plants would you advise for planting under an established beech hedge? I'd prefer that they be native if possible, and attractive to bees and/or butterflies at the least.

Answer: Hello Leigh. Planting beneath hedges is always slightly tricky as the hedge will generally out-compete most plants starving them of light, moisture and nutrients. However, with deciduous hedges there is a window of opportunity for spring flowering plants to receive sufficient light to thrive while the hedge remains dormant. Beech retains many of its old leaves until spring, creating useful dappled shade. Many spring flowering bulbs are well suited to such conditions and will also benefit from the leaf mould that develops at the base of the hedge if fallen leaves are left to break down.

I would suggest that you try spring flowering bulbs such as bluebells, crocus, snowdrops and muscari which also provide bees with valuable nectar at a time of year when it in short supply. Lily of the Valley and our native Primrose might also be worth a try if the soil is reasonably moist.

Name: Christina Goozee

Question: My "Day Lily" is amass of seed pods after the flowers Should I pick & store them now or wait until they have dried on the plant first please?

Answer: Hi Christina. I’m a little confused as the picture that you sent is not a Daylily (Hemerocallis) and I’m afraid that I can’t make out what it is from the picture. However, You can certainly start to collect the seedheads. I would suggest that you collect them at different stages to ensure that at least some of them will be ripe. Perhaps this article will help you.

Name: Christina Goozee

Question: Thanks 2 Peach trees Avalon Pride & Peregrine I bought from you this year .. To over winter can they stay outside, sheltered in my clothes drying area which has 3 sides & roof covered but the breeze or wind does get through or should they come in to the cool heated conservatory?

Answer: Your peach trees should be perfectly hardy and a sheltered position outdoors will be fine during the winter months. If the area is covered then this is even better as it will protect the emerging stems and foliage from late winter/ spring rainfall, thereby reducing the risk of peach leaf curl infections. However you will of course need to remember to water them throughout the winter if they are not receiving rainfall. Hope this helps Christina.

Name: Victoria Lewis

Question: I bought one of your perennial packs last year and planted them in October/November time. Only the eryigiums (sp) came up this year. Do you think I would have better luck planting them earlier this year?

Answer: Hi Victoria, the earlier you can plant your perennials in the autumn the more chance they have of establishing before the really cold weather sets in. You may also have less success with autumn planting if your soil is heavy clay, as these soils retain water and cause the plants to rot. Make sure you improve your soil by digging in lots of organic matter (well-rotted manure, compost or recycled green waste) each year. If your soil is heavy then make sure you break up the bottom of each planting hole with a hand fork to prevent water collecting. It may also be worth putting a layer of grit into the bottom of the planting hole to improve drainage. I hope this helps and good luck this year.