Numerous slugs and snails are threatening seedlings and potatoes. Sowing flowers now leads to strong plants next year. Spare soil grubs. Eucomis pep up late-summer gardens. Disconcerting figwort weevil damage is common this year.

Wet weather in some regions has suited slugs and snails (far right). In contrast to spring, most plants are now big enough to tolerate some grazing, so control is not necessary. Exceptions include potatoes “mined” by slugs. Lift and store once the skins are set, watering on nematodes if they are still leafy. Seedlings of annual spring cabbage, autumn and winter salads may also need protection. Hoe and clear up round the garden to expose slugs to sun and drying winds.

Sweet peas are the most important autumn-sown flower, being overwintered in freely ventilated greenhouses or cold frames. Many annuals, including grasses and wild flowers, also make strong plants if autumn-sown. Given a frost-free greenhouse or conservatory, autumn sowings of plants including antirrhinums, salpiglossis and schizanthus make strong plants for spring. Given reasonable warmth and light, the last two of these flower in winter, making interesting conservatory or greenhouse flowers.

Late-season weeding and root-crop harvesting often reveals caterpillars and other larvae, including chafer grubs. In addition, look for pupa including moth chrysalides. Unless very numerous, leave these, as they pose little threat to garden plants. In wilder parts of the garden, plentiful caterpillars support birds and bats, so go easy on autumn weed control. Watering on nematodes now can protect lawns from chafer grubs and leatherjackets next year, but is expensive “insurance” where attacks are not frequent.

With exotic spikes of flowers growing from a clump of narrow leaves with a leafy “topknot”, Eucomis flowers from now until October. Provide shelter, fertile soil and plenty of sun, water in dry spells and add a winter mulch to exclude frost. In colder regions, grow as a container plants and protect in the winter. Plant bulbs in spring. Good ones include Eucomis bicolor (purple-edged green flowers), E. pallidiflora (white/green flowers) and E. “Sparkling Burgundy” (red/purple leaves and purplish flowers).

Figworts, buddleias, verbascum and Phygelius may look worryingly disfigured now due to figwort weevil. Their larvae are 6mm long, yellowish and graze on leaf surfaces, causing the plant to dry up and go brown. Happily the plants often recover for next year. Keep an eye out for it from late spring until September. Picking off the weevils is often enough to prevent serious damage.

Guy Barter is chief horticultural adviser for the Royal Horticultural Society @GuyBarter

The Royal Horticultural Society is a charity working to share the best in gardening and make the UK a greener place. Find out more at rhs.org.uk

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