I’ve been tackling some of the gardening questions I frequently get asked at talks, events, on the radio and on the internet. I’m aiming to share my top 100 gardening questions with you and this is my next instalment. I do hope you find them interesting and that I answer some of your questions along the way. Of course if you have a question you would like answered, please post it in the comments section at the end of this blog post and I’ll tackle it in the next instalment of my top 100 gardening questions.
Question 1: Can I prune a stephanotis
I have stephanotis that I was given a year or so ago. It is trained around a hoop but has now outgrown the support and has produced long training shoots. Can I prune and if so when. Would it be a good idea to repot it at the same time?
Answer: Stephanotis is a really vigorous climber so it is not easily contained on the small hoop it was grown on as a houseplant. The good news is that it flowers on the new shoots that develop as the plant starts into growth in spring. Therefore the time to prune is late winter and early spring. I would repot at the same time into a larger pot using a lime free growing medium. Cut back those long shoots to within one or two nodes (where the leaves join the stem) from the main stems. Give your plant a larger support to grow up. Canes with flexible tie between them make a simple but effective trellis.
Question 2: Can I put sawdust on the garden?
I have quite a pile of sawdust left from cutting up logs: we have lost a couple of trees in the recent gales. Can I use the sawdust as mulch, can I put it on the compost heap, or should I just dispose of it?
Answer: If you use the new sawdust as mulch it will take nitrogen from the soil as it decomposes. I would only use it in this way under a mature hedge where you want to slow the growth. Even in this situation it can cause yellowing of the foliage of subjects such as laurel. It would be ideal added to the compost heap between layers of green waste such as grass cuttings and light prunings. It is never a good idea to use sawdust from treated wood on the garden.
Question 3: What's happened to bizzie lizzies?
I have always used impatiens, bizzie lizzies (impatiens), as summer bedding plants in my pots and baskets; I have a shady garden and these have always done well. They seem to have disappeared over the past couple of years because of the mildew disease that has affected them. Will they be available this year and if not, what’s the alternative?
Answer: Very few growers in the UK are growing impatiens, bizzie lizzies, because of the problems with the mildew. New Guinea impatiens seems to be resistant and will still be available however it does not seem to perform as well in shade. As an alternative I would look at begonias: there are some stunning new varieties appearing. The ‘Whopper’ series promise to be very popular for their stunning display and long flowering season. Fuchsias are also a good choice for your shady garden and they too have a long season. They are a bit hardier than begonias and impatiens and seem to survive those early frosts.
Question 4: Can you grow a blackcurrant in a pot?
I have moved to a house with a small garden and now most of my gardening needs to be done in pots. I miss my soft fruit, especially my blackcurrants. Could I grow a blackcurrant in a pot?
Answer: There is no reason why you can’t grow a blackcurrant in a pot. Because you cut the plant back after fruiting and allow the new stems to develop it will be very containable. Choose one of the more compact varieties such as ‘Ben Connan’ or ‘Ben Sarek’. Pot it in a nice big container, at lease 40cm (16”) in diameter and use loam based compost. It will need feeding with a high potash balance slow release fertiliser annually. A blackcurrant may not be the most decorative plant for a container but it does have wonderfully aromatic foliage and tan coloured winter stems.
Question 5: Is ash good for the garden?
We have a woodburner which produces a great deal of wood ash. I’ve been told I can use this as a fertiliser. Is this true and if so what quantity should I use around my plants?
Answer: Wood ash contains a small amount of potash and not much else. You can use it on the ground but it adds little. If left on the soil surface it normally just produces a slimy grey mess. I would recommend either forking it into the soil or adding it to your compost heap. It will not add much but it will not do any harm.
Question 6: What to do with a pieris?
I have an elderly pieris in the garden which has always produced lovely red shoots and sprays of white flowers in spring. Now over 30 years old it is very tall and leggy and most of the new growth is at the top. Can I do anything to revive it or should I replace it?
Answer: You should be able to rejuvenate your pieris by hard pruning, Wait until the flowers have faded and the plant has produced its first flush of new growth; then cut back hard by at least two thirds. Any lower, younger stems could be pruned more lightly. After pruning feed with an ericaceous fertiliser, mulch with leaf mould or ericaceous compost and keep the plant well-watered. It should soon produce a flush of healthy young shoots.
Question 7: How to no-dig growing veg
Can you tell me about the no-dig method of growing vegetables. I have really heavy soil which is difficult to cultivate. “No-dig” sounds very appealing.
Answer: The “no-dig” methodis based on feeding the soil organisms naturally and getting them to do the work. You clear the ground in autumn; it is really important to dig out any perennial weeds in the early stages. You then spread a layer of compost or manure over the compost in autumn and leave it for the worms to work on and drag down into the soil. If this is done annually and weeds are controlled with a hoe during the season the soil gradually improves and just needs raking is spring prior to sowing.
Question 8: How to help a thin privet hedge
I have a conical ornamental privet; one with tiny dark green leaves. Sometimes it produces tiny white flowers and it is now covered with tiny black berries but has become thin and lost a lot of its leaves. What can I do to revive it?
Answer: I imagine the privet you have is Ligustrum delavayanum. This has stiff twigs and tiny dark green leaves. It is not as tough and hardy as the common privet and does have a habit of shedding a lot of its leaves after cold weather in winter. This ligustrum is extensively used for topiary in warmer climates such as the Mediterranean. It grows well in pots but if it becomes starved it will often produce more flowers and consequently fruit in an attempt to produce seeds. I would trim it now if it wants trimming, Then I would feed with a controlled release fertiliser and top up with some fresh compost. You will find that the plant soon recovers as the weather warms up
Question 9: How to get rid of yellow patches in your lawn
My lawn has developed a number of yellow patches recently. I don’t have a dog and I haven’t applied any fertiliser or chemicals. The patches seem to have developed in the wet winter weather; any ideas?
Answer: If you’ve ruled out other causes this sounds like a fungal disease which could be fusarium or rhizoctonia. These are a problem where air is still and grass is fine during damp weather. Make sure that there are no leaves or debris lying around and rake the patches to remove thatch. Take care not to rake into healthy parts of the lawn. You could apply a lawn fungicide if available or contact a turf maintenance company. In the longer term application of an autumn lawn fertiliser and better lawn care to encourage stronger growth is the best solution.
Question 10: When to plant gladiolus
I have just bought some gladiolus corms to grow for cut flowers. Can I plant them straight away and if so how deep? Will I need to lift them and store them over winter to replant next year?
Answer: Yes, you can plant them as soon as the ground is workable. Choose an open sunny position on well-drained soil. Plant with three times the depth of the corm of soil over the bulb, about 20cm, 8” apart. If you are growing for cut flowers you can plant in rows; if using them as an addition to a bed or border I would plant in informal groups. Some lift the corms in the autumn and store them dry. In most areas with a milder climate they are fine left in the ground. In any case they are inexpensive to buy and I think it is worth the risk; you can always replant next year if the winter is severe.