Wisteria, wasps and winter crops
Prune wisteria
Wisteria vines are stunning when flowering in spring but summer reveals their thuggish tendencies. The invasive tentacles will lift weather boards, given half a chance. Trimming long, whippy summer stems will keep the rampant growth tidy over summer and improve next spring’s flowers. The aim is to restrict growth but allow flower buds to develop.
Cut back side stems to around 30cm from the main stem, leaving three or four leaves. Next season’s flowers grow from buds at the base of these leaves. You may need to do this several times over summer.
Look around the base of the main stem for suckers. Leaving the suckers in place over summer will reduce the overall vigour of the main stem. Remove the suckers in winter so you don’t end up with a wisteria thicket. On the other hand if you want the main stem to grow longer, remove the suckers right back to the base so they don’t compete for nutrients and water.
Paper wasp nest alert
Paper wasps have slim waists and long dangly back legs. You’ll often spot them hanging around wooden fences where they scrape away cellulose fibres to build their nests.
Queen wasps hibernate over winter and emerge in spring ready to start nests. Favoured places are on garden furniture, in hedges or on trellises – places gardeners are likely to touch.
Nests start with six or so hexagonal cells in a circle. Each cell contains an egg which hatches into a larva.
The queen feeds the larvae on caterpillars and other insects until they mature into female worker wasps ready to take over the nest building and feeding duties. The queen continues to lay eggs and the nest gets bigger as more cells are added. Midsummer is peak population-growth time.
Seek out and destroy the nests now so there’ll be fewer pests to feast on your grapes and other ripe fruit in autumn. At night, when all the wasps are home and less active, spray the nest with household bug spray or dust with Kiwicare No Wasps. Or, if you are brave, try this pesticide-free method: cut off the nest so it falls into a bag held underneath. Quickly seal the bag and pop it into the freezer.
Don’t bother destroying nests in autumn. They’ll be just about empty as all the larvae will have hatched. Groups of males flit about in sunny places to attract females. Once they’ve mated, females look for a safe hibernation place and the whole cycle continues.
What you can and can’t sow
It is too warm for peas and too late for watermelons, pumpkins, tomatoes, chillies and peppers.
You can direct-sow beetroot, carrots and radishes, and parsnips, swedes and turnips. Sow or plant lettuces and rocket but give them afternoon shade and keep them watered – if salad greens dry right out they are prone to bolt and heat stress will make them taste bitter. Fill any gaps with Asian greens for stir-fries and sow more coriander and basil.
Think ahead to your winter crops. If you want to grow broccoli, cabbages, cauliflowers or brussels sprouts from seed, you will need to start them this month in trays.