Back to basics: Courgettes

Last month I went back to basics with runner beans, a very popular, tender, summer crop. In some ways courgettes are similar in their requirements early-on for they cannot stand cold weather, especially at night-time. Lots of courgettes are killed off because they are started off too early in the year, yet when started and planted at the right time, they come into cropping in a matter of weeks.

Ground preparation

Choose an area of the plot in an open sunny position to grow your courgettes. Set the garden line and place a cane at one metre centres, then dig out a hole 60cm (2ft) square and fork through the base to combat poor drainage. Continue to dig the holes where you have placed the canes, then add one barrowful of well-rotted manure to each hole. If you cannot get manure, well-rotted garden compost or mushroom compost can be used instead.

When filling the hole filter in one forkful of manure then some soil then some manure and so on. Avoid a solid layer of manure as this can sometimes rot the roots. When you place the soil back onto the manure scatter in some slow-release sheep manure pellets. Pelleted chicken manure or Growmore could be used instead. By the time the manure and soil has gone back in the hole you have a mound approximately 45cm (18in) above soil level. If you can, prepare your planting stations six weeks before you want to plant out, this allows the soil to settle back with the manure and at planting time the mounds will be the correct degree of firmness. Don’t forget to apply a general fertiliser to the adjacent areas around the planting area and fork in.

Sowing your crop

I live in North Yorkshire and the correct sowing time in my area is at the end of April or early May. It takes me three to four weeks from sowing to having a plant at the stage to plant out, always bearing in mind courgettes are on the tender side, not liking cold nights.

Courgette seed is quite large, so it is easy to handle. I like to sow my seeds into cell trays – 15 cells per tray. Using a good multi-purpose compost fill the trays, tapping the full tray on the bench to firm in the compost. Water the compost well.

Do not sow courgette seed flat – sometimes water may lodge on the seed causing it to rot. Rather, sow the seed on its edge, pointed shape downwards so that the water runs away off the seed. The seed trays can then be placed on a propagating mat or heated propagator, set at between 13 and 15C (55-60F). Within five to six days germination should have taken place. Remove the trays from the heat and grow on in the greenhouse, making sure they are in a warm, light position where the night temperature falls no lower than 4.5C (40F). Ventilate well during the day.

Try to keep your plants sturdy – courgette plants grow very quickly; I transfer from the module trays to 13cm (5in) pots 10 days after sowing. When the pots are full of roots and if weather conditions permit, they can be planted. Place them in a well-ventilated cold frame prior to planting to harden them off thoroughly.

Courgettes in containers and the greenhouse

To grow courgettes in a container it needs to be big enough – as big as a dustbin – and well drained.

The same soil preparation is used as in the garden, one plant per bin. In a smaller container, you may get a few courgettes but the plants do not thrive.

Many people try to grow courgettes in growing-bags in the greenhouse. I often see three planted per bag, sometimes looking quite poorly. Fluctuations in temperature and lack of compost is the problem. Useful early crops can be grown in polytunnels but you will be fortunate if they last all summer long.

One of the questions cropping up on my radio programmes frequently is why do courgettes get to 7cm (3in) long and then go brown or drop off. This is often due to lack of fertilisation. On a courgette plant there are two types of flowers – male and female. The female flowers have an embryo baby courgette attached at the rear where the male flower is normally smaller and does not have an embryo courgette behind. One of the reasons the young courgettes do not form properly is lack of pollination or fertilisation. This can be corrected by removing a male flower and when the female flower is fully open, brushing pollen from the male to the female. During our summer months the job is nearly always completed by insects. When insects are scarce, pollination can be poor.

Joe’s favourite varieties

I have grown dozens of varieties in recent years. Here are some of the best:

• ‘Ambassador’ – this has been one of my best cropping varieties over the past 10 years. Dark green fruit.
• ‘Golden Zucchini F1’ – very bright yellow courgettes, very strong grower, good flavour, cylindrical in shape.
• ‘Defender F1’ – I find ‘Defender F1’ crops earlier than any other variety sown at the same time. Attractive and one of the best on the show bench as they are easy to match. Good flavour, too.
• ‘Taxi F1’ – this is the heaviest cropping, yellow courgette I have grown. Good quality and easy to pick.
•  ‘Parthenon F1’ – this is a parthenoncarpic hybrid (does not require pollination by bees) and so is more suitable for protective growing in tunnel or greenhouse.
• ‘Bambino F1’ – there is now a trend for using courgette flowers in cooking and many restaurants have deep fried flowers on their menus. This variety can be harvested with the flower on or it can be detached. Very heavy yields of baby, dark green courgettes.