Q&A: When do I prune my hydrangeas?

Red hydrangea
Q. When do I prune my hydrangeas?

A. I’m assuming you have Hydrangea macrophylla, either a mophead variety (as shown above) or a lacecap variety (which has flattened heads). These are the two most commonly grown hydrangeas in our backyards.

Pruning of mophead hydrangeas is often a matter of choice. Some gardeners like to prune in autumn (usually in warmer areas) to tidy their plants after flowering. Others prefer to prune in spring (best in frost-prone areas). Some just snip off the flower heads, and some don’t prune at all. In fact, macrophyllas don’t need pruning unless they’re old, large or becoming straggly. However, to keep them looking neat and tidy, [Read more…]

Q&A: Are banana skins good for my plants?


Q. I’ve heard that banana skins are good for roses. Are they good for other plants too?

A. Banana skins are rich in phosphorus and potassium, which are both essential nutrients for healthy plant growth. Phosphorus aids seed germination and root development, while potassium promotes flower and fruit production. Young plants, in particular, benefit from phosphorus while their roots are developing, and root vegetables, such as carrots and turnips, guzzle phosphorus like it’s going out of fashion. Potassium is especially good for crops or trees that bear fruit, and is used in the process of building starches and sugars in fruit and veggies. Tomatoes, peppers, apples, pears, carrots and parsnips, etc, all love it. Cut your banana skins into small pieces and mix them with fresh soil or compost when planting a new flower, vegetable or shrub. Or lightly dig it into the soil around existing plants. Jane

Q&A: Can I transplant my citrus?

Q. I’d like to transplant my lime tree to another location in the garden. When is the best time to do this? Bronwyn

A. The best time to transplant trees and shrubs is during winter when the plants are dormant, as this ensures minimal shock from root disturbance. For greatest success, a month before you actually shift your tree, dig a circle around the drip line to severe the surface roots. On the day of moving, dig a large planting hole that will accommodate the root ball. Then dig up your tree, keeping as much soil as possible intact around the roots to avoid further root disturbance. Plant the tree in its new home, watering deeply and regularly after planting. Do not fertilise the tree until after a burst of growth in spring, then use a special citrus fertiliser. Jane

Q&A: How can I control powdery mildew organically?

A bouquet of mixed dahlias
Q. Each year my cucumbers, courgettes, dahlias, gerberas, calendulas and other plants get powdery mildew. Is there a way to control this organically? Kelly

A. You can keep on top of powdery mildews with a homemade milk spray. The natural antibiotics in milk, as well as the production of other constituents upon exposure to sunlight, act as a natural fungicide. A dilution rate of one part milk to nine parts water is generally recommended; too much milk can encourage the growth of sooty mould. The spray should be used regularly, every 7 to 10 days, and a good coverage of the leaves is required. Bear in mind that this spray won’t get rid of your existing mildew, but it helps to keep it from spreading.
The baking soda method offers another organic solution. Mix 1 tablespoon of baking soda with a litre of water and spray it over the leaves. Jane

Q&A: Is horse manure ok for the garden?

Horse clip art from Graphics Fairy

Q. I can collect loads of stable manure (a mixture of sawdust and horse manure). Is this ok for the garden? Di

A. It is, but all animal manures need to be aged for at least six months before adding them to your garden. That’s because ‘raw’ manure releases nitrogen compounds and ammonia, which can burn plant roots and interfere with seed germination. You can dig raw manure straight into your soil, but you must leave the area for several months before planting up. Otherwise, add raw manure to your compost heap, or place it in a disused corner of the garden and let it age. Horse manure often contains weed seeds, so you may like to consider hot composting (where the pile reaches 45-65 degrees Celsius), to kill the seeds. For a hot compost heap, you need to build it all at once, instead of over several weeks. Jane

Q&A: Will my amaryllis flower next year?

Amaryllis from The Graphics Fairy
Q. I was recently given an amaryllis plant which produced two flower spikes and is now growing leaves. Is it possible to keep it in a way that it will flower again next year? Dorothy

A. Amaryllis, also known as hippeastrum, will flower the following season provided you follow a few basic steps. Once flowering has finished, cut the stems as close to the base as possible. Apply liquid fertiliser, as the bulb at this time will be storing nutrients for the following season. Keep watering your plant for the next two to three months. As flowering is initiated by a period of stress (about 10 weeks of either cool or dry conditions), stop watering your plant from the beginning of April until the end of June. You may lose some leaves, but don’t worry. In July, replant your bulb into fresh potting mix that contains a six-month slow-release fertiliser. The top third of the bulb should poke out of the soil. Your bulb should then flower about seven weeks later. Jane

Q&A: My sunflowers won’t set seed

Q. I would like to harvest my own sunflower seeds to eat. But last year my plants produced no seeds. I have planted a different variety this year. How can I be sure it will set seed? And if it does, how do I harvest them?

A. You need to make sure you grow a variety that produces them. Many modern-day sunflowers are actually sterile and therefore won’t produce seeds – check your seed packet to be certain. If it says pollen-free (great for those who suffer from hay fever) your sunflower won’t set viable seed if grown on its own or if it doesn’t get fertilised by a pollen-bearing variety. If you do have a seed-producing variety, cover the flower heads with frost cloth or old pantyhose when you notice the seeds beginning to develop, usually  late summer (this is to stop the birds getting to them before you do). When the heads start to droop and the backs turn yellow, the seeds are ready to harvest. Snip off the flower heads, leaving a 50cm stem, and hang in a dry, well-ventilated spot to dry. When seeds have loosened, place a piece of chicken wire over a bucket and rub the seed heads back and forth over the wire, letting the seeds fall into the bucket.

Q&A: How can I rid my garden of slaters?

Birds and bees from The Graphics Fairy

Q. How can we rid our beach garden of slaters? We laid plastic over the sand, put down shingle, then scattered shells and lime chips on top. But now we’re plagued with slaters.

A. Slaters like to congregate in damp areas, under bark or garden debris and in compost heaps. They usually feed on decaying vegetation, tree bark and rotting wood, but they occasionally nibble at young seedlings and root vegetables. While slaters occur in a wide range of habitats, they are much more abundant in lime-rich soils as they need lime to build their hard shells. Crushed shell is a natural source of calcium carbonate (the active ingredient in agricultural lime), and lime chips, while they break down extremely slowly, on first use will have a fine coating of lime dust, which will consequently wash into the soil. The best way to get rid of slaters is to remove their food source – any rotting plant matter that may be lying around – as well as possible hiding places, like old wood, bricks, leaf litter or rubbish.