- Certain ornamental house plants, including the India rubber plant (Ficus elastica) and the fiddle-leaf fig (Ficus lyrata), are grown for their large, glossy leaves and will benefit from regular cleaning to keep them vibrant and healthy. Using a moist cloth or a soft and pliable damp sponge, carefully wipe any dust off the leaves. Always deal with the plants early in the day, so they can dry again before nightfall. And resist the temptation to apply olive oil or furniture polish to the leaves to give them extra shine, as these can cause considerable damage.

- Decorative house plants with lots of smaller leaves, such as the weeping fig (Ficus benjamina), are often easier to clean if you stand them in the bath and gently rinse under the shower hose with tepid water. Lean the plants on their sides to avoid soaking the compost. If houseplants have hairy, sharp or spiky leaves, dust them with a soft brush instead.

- To ensure bumper crops this summer, fruit trees should be mulched using well-rotted manure or garden compost. This helps to keep unwanted weeds and grass at bay, reduces moisture loss during hot weather and provides valuable nutrients. For the best results, remove any weeds, then lay the mulch 2-4in deep around each tree. If the soil is dry, water the trees thoroughly before spreading the material over the ground.

- If you have a traditional box (Buxus sempervirens) hedge that has been trained into a formal shape, you can keep it in top condition with a light trim during late spring. Tackling the job with a sharp pair of hand shears is more environmentally friendly than using powered hedge clippers, and will give you more detail if you have a fancy pattern – though they might not be up to dealing with a larger hedge. The clippings can cause quite a mess so, to ensure that most of them are collected easily, lay a dust sheet along the foot of the hedge before trimming. The clippings can then be removed in one go.

- Courgettes are reliable vegetables that are simple to raise from seed and should be sown now. Choose a naturally disease-resistant variety, such as ‘Dundoo’, and bury the seeds, ½in deep, individually in 3in pots filled with moist sowing compost – leave them to germinate in a greenhouse or on a warm kitchen windowsill. In late May, harden off the young plants for a week by placing them outside during the day, then bring them back under cover at night. In early June, plant the courgettes 2-3ft apart in a sunny spot and a fertile, welldrained soil, or raise them in large containers on the terrace. During the main growing season, water the plants regularly and, once the first fruits appear, feed them every fortnight with an organic liquid fertiliser. For the best flavour, the courgettes should be harvested when they are 3-4in long.

- Outdoor climbing plants, including clematis, honeysuckles and passion flowers, are growing strongly by now, so any loose stems need to be tied to or wrapped around their support structures. If this is not done, they may smother other plants nearby or be damaged by strong winds. This is also an ideal opportunity to prune back stems that are becoming unruly and outgrowing their allotted space.

Your questions answered

How should I deal with asparagus beetles without using chemicals?

F Appleton, by e-mail

Red, black and yellow asparagus beetles (they are usually about ½in long) and their grey-black, humpbacked grubs feed on the leaves and stems of asparagus plants from May onwards. In severe cases, the leaves are completely stripped away and plant growth is checked. The best organic control measure is to examine the asparagus on a regular basis and pick off and destroy any beetles and grubs. It is also important to cut down the spent stems when they turn yellow-brown in the autumn and remove all plant debris from the surrounding area, as this prevents the adult beetles from overwintering on them and infesting the new growth the following season.

My penstemons are very tall and leggy. Can I cut them back?

H Ward, Droitwich

Penstemons are delightful border perennials with spikes of tubular-shaped summer and autumn flowers, which are pink, purple, blue, red or white. To ensure the plants thrive, they should be positioned in a sheltered, sunny border and a welldrained soil.

When penstemons are left to their own devices, the stems often become woody and very leggy. Fortunately, they can be pruned now – and this will encourage vigorous new growth and keep the plants compact and bushy. Simply cut back the stems to young leaves held further down each stem, even if they are close to ground level. Afterwards, remove any weeds that were lurking underneath and give the plants a feed.

I want to establish a living roof on my shed, using flowering sedums. Where can I buy the plants?

J Armstrong, by e-mail

Sedums are perfect for creating a living roof on garden buildings, provided that the roof is sturdy, waterproof and not built at not too sharp an angle – otherwise everything might just slide off. These succulent plants are hardy, evergreen, low-growing and drought-tolerant; and, as well as being low-maintenance, they produce colourful flowers for up to nine months of the year. For ease, you can buy specially created sedum “mats” – rather like rolls of carpet – composed of different species for long-lasting colour and interest. These can be unravelled and laid in situwithout the need for soil. For more information on creating a living roof, or to buy sedum mats, call Enviromat on 01842 828266 or visit www.enviromat.co.uk.

The young leaves of my container-grown Japanese maple have brown margins. What is the problem?

P Rogers, Skegness

Japanese maples (Acer palmatum) are slow-growing deciduous trees that are planted for their elegant display of lobed and deeply dissected green, purple or red leaves, which take on fiery shades of gold, orange and crimson before falling in the autumn.

Unfortunately, the young leaves of these plants are vulnerable to cold and drying winds, as well as hard frosts. These cause the edges to turn brown, especially when they emerge in mid- to late spring. There is little that can be done to remedy the situation once it has occurred, but, to prevent problems in the future, move the container into a semi-shaded spot, out of the wind, and keep the compost moist throughout the main growing period.

Neil Wormald is a qualified horticulturalist. Send your questions to Garden Expert, Home, The Sunday Times, 1 Pennington Street, London E98 1ST, or e-mail garden.expert@ sunday-times.co.uk

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