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

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

    April is one of the busiest months and one filled with immense responsibility. All your crops are now sown and you care for them as if they are your little babies. You certainly can’t book a holiday during April because your seedlings in trays need to be watered every day and possibly twice if it’s hot.

    Sowing in the Polytunnel

    Direct sowing into beds

    You can sow radishes and baby turnips directly into the beds if there is space available.

    Planting into polytunnel beds

    You can now plant out the seedlings you raised earlier on your heating bench: calabrese, mini cauliflowers, celery, chervil, coriander, courgette, dill, French beans, kohlrabi, lettuce, oriental salads and scallions.

    Sowing into modules/pots (18-20˚C)

    In April you can sow the following vegetables into modular trays and place them in your propagator or warm, south-facing windowsill in the house:

    • Basil (Sweet Genovese) – 4 seeds per cell
    • Celery (Victoria F1) – broadcast in a tray for pricking out later
    • Courgette (Defender F1) – 1 seed per 7cm pot
    • Cucumber (Passandra F1 & Styx F1) – 1 seed per 7cm pot
    • Coriander, Dill and Chervil – 5 seeds per cell
    • French beans (climbing and dwarf) – 5 seeds per 9cm pot
    • Kohlrabi (Azur Star) – 1 seed per cell
    • Lettuce (various types) – 1 to 3 seeds per cell
    • Melon (Emir F1) – 1 seed per 7cm pot
    • Sweetcorn (Sweet Nugget F1) – 1 seed per 7cm pot

    For planting outside

    You can also raise the following vegetables indoors for planting out into your vegetable garden later.

    Brussels sprouts, cabbage, calabrese, cauliflower, chard, chervil, coriander, courgette, dill, endive, kale, kohlrabi, leeks, lettuce, parsley, perpetual spinach, pumpkins, scallions, squash, swede and turnip.

    Harvesting from the Polytunnel

    In April you’ll get your first rewards from your tunnel or greenhouse. You’ll be harvesting a whole range of exciting, delicious and healthy crops:

    Early Hispi cabbage, lots of lettuce, radish, scallions, baby turnips , kohlrabi, salad rocket and other oriental salads, spinach, chard, strawberries and even some baby potatoes.

    General greenhouse/polytunnel jobs

    • Water more frequently now.
    • Ventilate as much as possible.
    • Prick out celery and celeriac seedlings into modular trays.
    • Pot on aubergines, peppers and tomatoes into 10cm pots using good potting compost.
    • Most of the overwintered crops (oriental salads, spinach and chard) will have bolted by now and should be pulled.
    • Keep a watch out for pests, especially aphids on a variety of crops and leatherjackets and cutworms on newly planted lettuce.
    • Spray aphid susceptible plants with a garlic spray every ten days.
    • Prick out and pot on plants as necessary.
    • Towards the end of the month lower the temperature of your propagator to 15˚C to harden off your tomatoes, peppers etc. before planting them into the beds next month.

    Thanks to John Harrison of Allotment & Gardens

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

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