I’m trying to tackle the top 100 gardening questions I get asked on the radio, at talks and events, by post or when I am out and about amongst gardeners. Similar questions are posed time and time again; we all face similar challenges! Please add your comments and questions at the end of the post. Maybe you can come up with different answers? Remember there is never a right and a wrong way to do things in the world of gardening: fortunately plants have never read the text books.
Also please share this post and others through social media; I believe there is always something new to learn, however long you have been gardening. This is my fifth post in this series: fifty down and fifty to go – we are only just at the half way mark!
Q1. I have had trouble establishing Anemone blanda and winter aconites Eranthis hyemalis in my garden. I plant them in what appears to be an ideal position, for example in groups around trees, and nothing appears. Have you any suggestions?
A. Eranthis and Anemone blanda grow from small tubers. These can become very dry in storage and may be reluctant to rehydrate in the ground if planted in dry conditions. Sometimes the soil at the base of trees and shrubs is very dry, even in autumn and winter and the tubers just do not get enough water to grow. Try starting them in pots of multi-purpose compost. Plant 5 tubers about 3 cm, 1 inch, deep in a 10cm, 4 inch pot, and keep them outside in a sheltered position where mice and slugs cannot harm them. Keep the soil moist and plant in position in spring. From then on they should establish and appear every year. Winter aconites do like a soil that is rich in organic matter and one that does not dry out completely, even in summer.
Q2. I have a large Physocarpus ‘Diable D’Or’ which has grown very well and is now a bit too big for the bed. When and how do I go about pruning it? You always say prune after flowering, but this would mean losing the best of the foliage in midsummer, and the red fruits that follow the flower clusters.
A. I prune mine in winter, once the leaves have fallen. If you look at the shrub in winter you will see that the younger stems are light tan in colour, quite shiny and with few side branches. The older stems that have flowered are darker and more branched. I cut out some of the older stems right back into the plant, by at least two-thirds of their length. This way you preserve the elegant arching habit of the plant and keep an open structure. You can of course also remove any stems that are competing with neighbouring shrubs or overhanging paths.
Q3. I want a colourful shrub for a dull corner of my small garden. Ideally I would like something evergreen that does not need much attention. The rest of my “garden” is in pots: heucheras, bulbs and a few bedding plants for both winter and summer.
A.For all year round interest I would always recommend that you choose a good foliage shrub rather than worrying about flowers. Evergreen foliage means easy maintenance because you do not have to think about dead heading. I rate Osmanthus heterophyllus ‘Goshiki’ very highly for all year interest. It has a lovely suffused creamy gold variegation on a dark green background. However it is not an unchanging evergreen; the new copper coloured shoots transform its appearance as they appear in late spring. Eventually this shrub can reach 1.8 metres, 6ft in height, but do not be put off because it is slow growing and can be trimmed to restrict its size. It would look great as the backdrop to pots of caramel coloured heucheras and scarlet leucothoes.
Q3. I have three large blackcurrant bushes which have in the past produced a good crop of fruit with very little attention from me. Over the past two or three years the crop has diminished and the bushes look poor. A redcurrant growing in the same spot seems to keep cropping well. What can I do to reinvigorate the blackcurrants?
A.Blackcurrants do need regular pruning to maintain their vigour. You need to cut out at least one third of the branches each year after the fruit is harvested to allow new shoots to develop from the base of the plants. If you do not the plants gradually become overcrowded with branches and the cropping diminishes. Redcurrants on the other hand crop on branches of all ages and are more tolerant of neglect. You have two possible courses of action either: prune them hard, removing about two thirds of the older branches or replace the plants. Personally I would go down the latter route. Autumn, fall is the ideal time to think about planting new soft fruit bushes. New virus free stock will give better crops and you can manage them properly from the outset.
Q4. I have a small sunny garden with a patio, a few pots and a narrow border. The soil is really poor and few things seem to thrive. What can you recommend that will grow and give me some colour?
A.The perennial wallflower, Erysimum ‘Bowles Mauve’ sounds perfect for your situation. It grows quickly to form a rounded shrublet 60cm(2ft) high with a similar spread. The spikes of purple-mauve flowers are produced from spring until late autumn. It is not a long-lived shrub but it will give great results and value for money. I would team it up with the purple sage, Salvia officinalis ‘Purpurascens’ which likes similar conditions and has lovely purple-green foliage throughout the year. Lavenders will also do well here as will the rock-roses. Helianthemum ‘Rhodanthe Carneum’ is a reliable favourite with single pink flowers with golden stamens. All o these subjects are attractive to bees and butterflies so will do a great job bringing your garden to life.
Q5. I have a small lawn surrounded by flower borders. Despite my efforts for much of the year the grass is poor and riddled with moss and weeds. Should I start again and have it re-turfed?
A.Lawns in small gardens are often a problem. You still need a mower and all the associated equipment and they tend to get a lot of wear and tear; even if it is only from you tending to the surrounding planting. Personally I would consider getting rid of the grass and putting down gravel or stone chippings, perhaps with some random paving stones. This can be softened by including thymes, sedums, dianthus and other mat forming plants which will give you a far more interesting area. Some lay a weed control membrane under the gravel. I think this restricts planting and may prevent you from including dwarf bulbs and planting where you want to. Also the gravel slips and moves on the membrane. You will achieve a more pleasing effect by using an aggregate or sand base under the gravel and stone slabs.
Q6. My garden is overlooked by a neighbouring house extension. Can you recommend a fast growing evergreen that will give me some privacy? My garden is small and I don’t want anything that is going to take over.
A.I would choose a plain green variety of Pittosporum tenuifolium. This has small, shining green leaves on dark stems and is well-branched and bushy. As it matures it may grow broader than you want it to but it responds well to clipping. Therefore an occasional trim to the sides of the plant should produce an attractive green column which will achieve the result you are looking for. Alternatively you can remove the lower branches to achieve a tree effect leaving bare stems and a dense bushy head that will screen overlooking windows.
Q7. I have several miscanthus grasses in the garden. I never know when the right time to cut them back is. Should I do this in late autumn, or leave it until spring.
A.Miscanthus are at their loveliest in early winter when the plumes and leaves turn to parchment. In a dry winter these can last in good condition until late winter. In a wet one they often turn soggy and shed leaves before the end of the year. The simple answer is: use your discretion. As long as they look good leave them and cut them back as soon as you can see the new shoots emerging at the base of the plants. This is also the best time to lift and divide them which you really need to do every three years or so.
Q8. I had lovely bearded irises in the garden. Now they produce quite poor foliage and rarely flower. Have they had their day or is there anything I can do to revive them?
Bearded iris rhizomes eventually become overcrowded and performance declines. Lift the rhizomes and save the youngest, healthiest sections. These are the ones nearest to the growing points; usually the ones with leaves; shorten the foliage back to about 15cm (6ins). This is usually done after flowering but if the plants are not doing much then you can tackle it in autumn, winter or early spring. Condition the soil and add slow release general fertiliser. Then replant anchoring the rhizomes on the soil surface in groups. This may be easier achieved by pushing stout pieces of cane into the soil any tying the foliage onto the canes if there aren’t many roots. Your irises need an open, sunny position and resent competition from neighbouring plants. Plant them so that the rhizomes get as much sun as possible and are not initially shaded by the leaves.
Q9. I want to grow some lilies in the garden. When is the best time to plant them? Do I have to wait until after the frosts if I buy them in autumn or spring?
A.Lily bulbs are made up of fleshy, waxy scales that dry up and shrivel when they are out of the ground for too long. The secret of success is to plant them as soon as you buy them whether that is in autumn or early spring. If buying from a shop then avoid bulbs which look dry with loose, open scales. A good tip is the plant the bulbs on their sides. This prevents water from running down between the scales and settling in the base of the bulbs which can cause rotting. Plant the bulbs three to four times the depth of the bulb beneath the soil surface.
Q10. Someone has given me a lovely indoor azalea. I know it likes plenty of water, and someone told me this has to be rain water; is this true? Does it need feeding?
Azalea indica, the Indian azalea is not hardy so is used as an indoor flowering plant in winter and spring. It is a shrub from cool regions and needs plenty of moisture; it hates hot dry conditions. Give it plenty of light and position in a cool room or conservatory. It needs regular watering; this can be every day if house is warm. The best way is to immerse the pot in a bowl or bucket of water until it stops bubbling; then lift out and drain. It is a lime hating plant so rain water is desirable. If you haven’t got it don’t panic; just leave the water to stand overnight before you water if possible, or use cooled water from the kettle. Feeding isn’t really necessary until after flowering when you should use an ericaceous fertiliser. Stand the plant outdoors in summer in a lightly shaded spot if possible.