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  • What to sow, plant and harvest in your polytunnel or greenhouse in July

    What to sow, plant and harvest in your polytunnel or greenhouse in July

    Your polytunnel or greenhouse is absolutely packed and you’ll be harvesting fruits from your summer crops – the first tomato of the year is always the most anticipated and delicious. Soon you’ll have more food than you can cope with. All the other summer crops (cucumbers, peppers, aubergines etc) are also starting to produce.

    Peppers ripe for picking

    Direct sowing into beds

    There shouldn’t be any empty space in your tunnel or greenhouse for direct sowing!

    Planting into beds

    You can plant all the crops you have sown a month earlier in modular trays into your tunnel or greenhouse:

    Basil, Chinese cabbage, coriander, dill and chervil, courgette, cucumber, French beans, Florence fennel, lettuce, pak choi, parsley, scallions.

    Ready to harvest cucumbers

    Sowing into modules / pots (18–20°C)

    It’s surprising how many crops you can sow in July for planting into the tunnel or greenhouse about four to six weeks later.

    • Basil (Sweet Genovese) – 4 seeds per cell
    • Calabrese (Green Magic F1) – 1 seed per cell
    • Chinese cabbage (Yuki F1) – 1 seed per cell
    • Claytonia (or Winter Purslane) – 5 seeds per cell
    • Chervil, Coriander, Dill – 5 seeds per cell each
    • French beans (climbing and dwarf) – 5 seeds per 9cm pot
    • Florence fennel (Rondo F1) – 1 seed per cell
    • Lettuce (various types) – 1 to 3 seeds per cell
    • Oriental brassica salads (all types) – 5 seeds per cell
    • Pak Choi (various) – 1 seed per cell
    • Parsley (curly and flat leaf) – 4 seeds per cell
    • Scallions (Ishikura Bunching) – 10 seeds per cell


    In July you’ll be assured how worthwhile it is to have a tunnel or greenhouse. Hopefully you are not away on holiday otherwise your neighbours or friends will enjoy your bounty in exchange for a little bit of watering.

    It is very important to harvest your crops regularly. You should harvest your courgettes and cucumbers at least twice per week and your tomatoes, peppers and aubergines at least once per week. If you don’t, the plants often get exhausted and diseased.

    You can harvest:

    Aubergines, basil, chillies, coriander, courgette, cucumber, dill, Florence fennel, French beans, lettuce, melons, pak choi, parsley, peppers, salads, scallions, spinach, tomatoes.

    Tomatoes growing in a greenhouse

    General greenhouse / polytunnel maintenance

    • Water more frequently and more heavily now, probably about three times per week, especially during hot spells.
    • Ventilate as much as possible. The tunnel and greenhouse doors should be left open until late in the evening or even throughout the night. Ensure that they are secure.
    • Weekly maintenance for summer crops: side-shooting and training tomatoes, cucumbers and melons. You should also remove the lower discoloured or diseased leaves.
    • Harvest regularly when the crops are ready and not necessarily when you would like them.
    • Keep a watch out for pests, especially greenhouse whitefly, aphids, red spider mite, slugs and snails.
    • Keep weeds down. They compete with your plants and create a damp atmosphere. This reduces the air-flow between plants and fungal diseases thrive in these conditions.
    • Spray aphid susceptible plants with a garlic or seaweed spray every seven days.

    Thanks to John Harrison of Allotment & Gardens

    You can get John’s book Vegetable Growing Month-by-Month here.

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