Make the most of your free seeds bundled with this month's GYO using Anthony Bennett's sowing, growing and harvesting guide
Courgettes are renowned for producing heavy summer yields, and are also an easy veg to get underway. Once established they grow at break-neck speed and can form up to 30 mildly nutty fruits per plant. Given their capacity for growth, you’ll need a healthy appetite to enjoy them fresh, although they also make ideal freezer vegetables for use throughout the winter. The fruits can be used as tasty additions to savoury dishes or as the basis of sweet recipes such as cakes. Just three or four plants will supply a family all summer long and even give you some to spare, making this a crop that merits a spot in every veg patch.
Not so long ago, courgettes were only available in one colour – green. But today they can be found in bright-golden yellow and all shades of green from a pale, almost-white, through to far darker varieties. There are also ball-shaped fruits, perfect for scooping out and stuffing. Courgettes are simply immature marrows. If left to grow on, they will reach whopping sizes. When buying your seeds make sure you definitely have a courgette variety, as these have been bred to produce lots of flavoursome mini-fruits rather than focus on a few large marrows. If you have plenty of plot space, then try adding some colour to your dinner plate by growing and serving popular greenskinned types alongside stripy varieties.
As they originated in Mexico’s warm climate, it will come as no surprise that courgettes need a sunny, sheltered position in order to ensure the best possible growth. The soil should be fertile, moisture-retentive yet free-draining. They are heavier feeders than most other crops, so the richer the soil the better their performance will be.
Thankfully, even the poorest spot can be prepared to provide suitable conditions. The best way to do this is to dig out a 30cm square hole to one spade’s depth where each plant is to be positioned. Space the holes at least 60–75cm apart. Fill the bottom third of each hole with well-rotted manure or garden compost and then backfill with soil. Do this at least two weeks before planting or sowing to give the soil enough time to settle back down. Don’t worry if you’re left with a mound over each planting hole – this won’t pose a problem and will reduce on its own with time.
Alternatively, dig out your planting holes in late autumn and line them with old cardboard. Infill the holes with compostable material, such as kitchen waste, as you produce it. When the holes are a third full, backfill with soil. These ‘compost pits’ of raw organic matter will feed the hungry plants.
Seeds can be sown directly into their final planting position or under cover for extra warmth. If slugs are a problem in your area, then start off seedlings indoors or in the greenhouse to give the plants a head start and reduce the chances of an early attack.
Raising seedlings under cover is generally more reliable as the conditions of early growth can be closely monitored to give a steady, even growth rate and strong young plants. Sow two seeds into 7cm pots of multi-purpose compost. Water these and place them in a propagator to germinate or onto a warm windowsill. The seedlings will push their way through in as little as a week. Sowings under cover should be made around one month before the last frost, from about mid April to early May, so the seedlings will be ready to plant out once the weather has improved.
If you opt to sow the seeds outside, wait until any danger of frost has past – late May in the south and up to early June further north. Warm the ground with cloches, if possible, or use clear plastic drink-bottle halves placed over the soil to create a mini greenhouse (these are also great for keeping slugs at bay). Push two seeds about 2cm into the soil, edge side down, and water them in.
Once the fat-leaved seedlings have emerged allow them to grow on for at least two weeks before removing the weakest and leaving a single plant in each pot or planting position. The young seedlings will soon go on to form their first adult leaves. Keep cloches or plastic bottle-halves over outdoor seedlings in these early stages to encourage strong growth while the weather continues to warm up.
Pot-raised seedlings should be transferred to larger, 12cm-diameter containers as soon as roots begin to poke out from the bottom of the drainage holes. Use multi-purpose compost and keep them in a bright position at a minimum temperature of 15°C. Begin to harden the young plants off about two weeks before planting out time. To do this, place them outside for increasingly longer spells and during milder nights to toughen them up. To plant, simply remove them from their pots and carefully lower them into planting holes at the same depth they were at within the pot. Courgettes can also be cultivated in grow bags, but you will only be able to place two per bag and they will need far more watering than crops such as greenhouse tomatoes grown in the same way.
To help with watering, insert a plastic pot, open side up, into the soil close to the stem of the plant. Your water and liquid feed can be poured into this pot, which will dispense it in a controlled flow from its drainage holes. Another option is to bank up the soil in a 5cm ridge around the edge of the planting position to create a reservoir which will be flooded during watering. This will stop the water running straight off the surface of the soil, and is particularly useful for soils that can bake dry and hard.
Courgettes are greedy plants, so the two golden rules are to water well and keep them fed. The former is especially important once the plants begin to flower and as they develop their fruits, as the amount of water is directly proportional to the speed of fruit production. In the height of summer each plant will need as much as 10 litres every week, so a good soaking every other day is vital. Apply a mulch in hot weather to lock in the moisture and keep weeds down. Garden compost, grass clippings or manure will all work, but be sure that the mulch does not touch the stem of the plants or the concentration of nutrients could harm them.
Towards the end of the season some of the leaves may take on a dusty grey appearance. This is the fungus powdery mildew and although it isn’t ideal, in small doses it does little to affect the productivity of plants. Good levels of water will help keep this to a minimum as plants will grow stronger. In nutrient-rich soils that have been further enriched with manure and compost there will be little need for extra feeding during the growing season, but on sandy soils plants will benefit from an organic liquid feed, such as comfrey tea or liquid seaweed, every two weeks.
Correct picking of courgettes is almost as important as all of the nurturing of the plants up to this point. With the right conditions you’ll be tucking into homegrown fruits as soon as 12 weeks after sowing. And once you start, the plants will keep cropping for some time to come.
Pick the fruits while they are still young, at about 10cm in length. Baby courgettes – those posh packets of slender fruits you’ll find in the supermarket with the flowers still attached – can be enjoyed even earlier. Try them dipped in batter and fried (perhaps even stuffing the flowers Italian-style with a little cheese and slithers of anchovy). Once you harvest the first courgettes keep picking them, as this will ensure the plants continue producing fruits. Thoroughly check over each plant at least three times a week and cut off the courgettes using a sharp knife. Hold the fruit with your hand while removing it and do not tug at the plant.
Courgettes are best enjoyed fresh but will keep for up to a week in the fridge. Male flowers tend to appear a little earlier than female blooms. The latter have a slight bulge immediately behind the flower (this is the embryonic fruit). The earliest male flowers can be fried as above and will offer a tantalising glimpse of the bounty to come. Always pick excess fruits and, if you can’t manage them all, slice them up and blanche them for a minute before drying them off and packing them into polythene bags for the freezer.
Order in seed catalogues and decide what to grow. Try one of the coloured or more unusual varieties as well as popular green types for a good mix on your dinner plate.
Finish filling your compost pits with suitable material before back filling the rest of the planting holes with soil.
For a really early crop and in mild parts of the country make a sowing of courgettes at the end of March.
By mid-month you'll be eating the first courgette fruits. Keep plants very well watered and consider applying a moistureretaining mulch to the soil surface.
Maintain a steady supply of water and begin feeding plants with a liquid fertiliser to maintain productivity. Don't let the courgettes grow too big – keep picking them young.
September will continue to see heavy yields of fruits but by the end of the month the rate of production will begin to tail off.
With the date of the last frost getting increasingly earlier it’s worth taking a bit of a gamble and sowing a few seeds a little sooner than normal. Sow into pots indoors from March onwards and grow them on as usual in as bright a position as possible. Harden them off from late April before planting them outside under cloches that have been in place at least two weeks beforehand to warm up the soil. If you don’t have cloches then make sure you have some fleece to hand to drape over plants if temperatures get too low.
The main problem with early crops is the lack of pollinating insects that are around to fertilise the female flowers and help them set fruit, so you may need to give them a helping hand. To do this, pluck a male flower (one without a swelling behind it), remove the petals and gently brush the centre of it against the centre of a female flower (which has a swelling behind it). There are also some fantastic varieties available that are ‘parthenocarpic’ – meaning the female flowers set fruit without needing to be pollinated. These include ‘Cavili’, which has a pale-green colour, and the deep-green ‘Parthenon’.
Related Forum Topics
Courgettes: Varieties To Try
All Green Bush
GYO is giving a FREE packet of ‘All Green Bush’ seeds away to every reader – just check the cover of this issue! This tried-and-tested favourite is a heavy-cropping bush variety. The mid-green fruits have a good flavour and can be harvested all summer long.
A great variety for really early crops or as insurance against poor, wet summers and low light levels. Its female flowers do not need pollinating, which means you’ll be virtually guaranteed a crop no matter what the weather. The fruits are deep green and glossy.
These bushy plants produce tasty, straight yellow fruits. The stems are also flushed with yellow, making this a real head-turner when it’s grown next to green varieties. The plants are slow to succumb to mildew, ensuring a long cropping season.
If you want a ball-shaped courgette then this is the one to pick. It has a bushy, compact habit and produces dark green fruits that can be grown up to tennis ball-size for stuffing or picked young for eating raw in salads during summer and autumn.
Containers And Compost
Almost every courgette variety is a bush type, which means it won’t sprawl all over the surface and instead forms a fairly upright, compact plant. This makes courgettes far more suitable for container growing than their gangly marrow counterparts. To grow in pots start seeds off indoors then plant them out into generously-proportioned containers that will hold at least 15l of good-quality multi-purpose compost. Leave a 2–3cm gap from the top of the compost surface to the rim of the pot so that they can be flooded at watering time. You will need to supply the plants with a liquid feed sooner and more often than those grown in the ground, which will have a greater root run and access to richer soil.
Another option is to grow plants on the compost heap. The planting holes are prepared in a similar way those made in the ground, although this time you’ll be ‘toning down’ the richness of the compost by adding a bucket or two of soil to the planting positions. Courgettes allowed to grow over or on top of open compost heaps are at greater danger of drying out so keep an eye on water levels. On the up-side, the hungry plants won’t go short of nutrients.