Courgette Growing Guide

When to sow courgette seeds

Courgette and Courgette Flower

Sowing courgette seeds is best done at the following times:

  • In a heated propagator like our Vitopod heated electric propagator or heated greenhouse – sow April to May.
  • In an unheated propagator or unheated greenhouse – sow May to June.
  • How to sow courgette seeds:

  • Fill a seed tray with compost and flatten the compost down lightly. Use a Tamper to firm and level the compost, as this removes air pockets that can lead to water logging.
  • Place seeds on the surface of the compost, space the seeds evenly and sow a few more than you need. Cover the seeds with approx. 1 to 1.5cm of compost.
  • Water the compost so that it is damp but not saturated.
  • If you have a propagator put the seed tray in the propagator and put the lid on.
  • Put the propagator/seed tray in a warm place away from direct sunlight, the seeds will need to be kept at a temperature of 18oc.
  • Caring for courgette seedlings:

    After about around 2-3 weeks seedlings should start to appear, some varieties may take longer so check your seed packet first. Once the seedlings have appeared transfer the propagator/seed trays to a bright, warm spot. Keep the compost moist but not wet. If you are using a propagator open the vents when all seedlings have appeared.

    Transfer courgettes to pots

    Once the seedlings are around 3cm tall they will be large enough to be moved into individual 3 inch pots.

  • Fill a 3 inch pot with compost and use a dibber or pencil to make a hole large enough for the seedling.
  • Hold the seedling by its seed leaves (not its stem) and gently lever up and out of the seed tray with a dibber or pencil and lower the seedling into its new pot.
  • Gently firm the compost around the plant ensuring the roots are covered and adding compost to fill the pot.
  • Water the compost so it is damp but not saturated.
  • Place the pots back into the propagator.
  • Transfer courgettes to their final pot:

    Once the plants around 10cm tall plant them into your Quadgrow or other chosen pot between 6 and 12 inches in diameter (see seed instructions for ideal pot size). If using a Quadgrow follow the assembly instructions.

  • Fill your pots with multi-purpose compost.
  • Make a hole in the compost large enough for your plant.
  • Remove the plant from its put and place in the hole. Surround the plant with compost, firming compost around the plant and add more compost to fill the pot.
  • Water so that the compost is damp but not saturated.
  • Caring for your courgettes

  • As your courgette grows, support it with stakes
  • Courgettes have a lot of foliage and therefore use a lot of water on hot days, ensure your plant does not dry out but do not over-water.
  • Harvesting courgettes

  • Courgettes can be harvested once they are 10cm long however this can vary depending on the variety, using a sharp knife or secateurs cut the fruit from the plant.
  • Regularly harvest your courgettes through the growing season to encourage continued production.
  • Possible Problems

  • No fruit – This is a physiologic problem caused by the growing conditions preventing adequate pollination. It is usually temporary just remove the affected fruit to encourage further flowers. Alternatively you could choose a parthenocarpic variety such as Cavili or Partenon, these have the ability to set fruit without pollination
  • Powdery mildew – Caused by erratic watering or excessive humidity levels, ensure that the compost is always moist but never waterlogged, remove any infected foliage to prevent further infection. Ensure that your greenhouse is well ventilated during hot days.
  • Botrytis – Also called grey mould, this looks like a fuzzy grey mould and can affect all parts of the plant. Typically will attack plants via wounds however healthy plants can also contract it. There is no cure for Botrytis, any plant material should be removed and destroyed, care should be taken to avoid cross contamination. Botrytis is encouraged through wet conditions, particularly where ventilation and overcrowding are a problem.