July is usually one of the driest months, so watering can be essential. To help with this, hoe regularly to break up the soil and remove weeds. Water in the cool of the morning or evening.
Keep up with the harvesting of all crops because the allotment is now in full production. Lift early potatoes and carry on earthing up the rows. Harvest garlic and shallots as the foliage begins to become yellow and straw like. Pick the first of the early tomatoes. July is the start of globe artichoke season. If your plant is into its second year then cut off the top bulb once big and swollen with a couple of inches of stem attached. Lift autumn planted onions for immediate use. Continue to pick rhubarb until the end of the month and begin to harvest the main crop of your strawberries. Start to pick plums, early pears and apples.
Sowing and planting
Start sowing the seeds of the overwintering crops of kales, spring cabbage, radicchio, chicory, spinach beet and a hardy type of onion to mature in the early summer of next year. Now is the best time to sow the main crop of carrots to avoid attack from root fly. Continue with successional sowings of beetroot and lettuce. Follow the instructions on the back of the seed packet, and sow every 2 – 4 weeks for a continuous supply of crops.
Plant out the last of your marrow, pumpkins, squashes, overwintering cabbages and leeks. Cover with netting to help protect them from the birds.
Aim to keep the hoe moving at every opportunity. Water all crops at least once a week. Start to draw the soil up around the base of Brussels sprouts and sweet corn plants to encourage extra roots.
Pest and diseases
This is the start of potato blight season, and if the weather is wet and humid in July then your crop is likely to be at risk. You can use fungicides containing copper to help protect your crop from the blight; these should be sprayed from June onwards if a wet July is predicted. (Crop rotation the following year is advisable). An infected plant will have a watery rot on its leaves, causing them to collapse – the infected matter should be binned or burned and not placed into your compost, as this will not kill the disease and it will reoccur the following year.
The main pests are aphids, cabbage white butterfly caterpillars and pea moth. Spray to control the aphids and pea moth with an insecticidal soap brought from the garden centre. Use the biological control of a pathogenic nematode, Steinernema carpocapsae, (trade name Nemasys Caterpillar Killer) to kill the caterpillars. (The other bio control often cited is Bacillus Thuringiensis, but unfortunately this is not available to amateur gardeners.)