If you want one crop that gives back tenfold for very little fuss, learning how to grow courgettes is a brilliant place to start. Courgette plants are some of the most generous in the vegetable garden: easy from seed, quick to crop and so productive that a single plant can keep one person in courgettes all summer. One or two plants will comfortably feed a family, with plenty spare to give away.
Squash belongs to the same easygoing family, and the two are grown in almost exactly the same way. The difference is mostly in the timing and the harvest. Courgettes are picked young and eaten fresh through summer, while winter squash, pumpkins and marrows are left on the plant to mature, then stored to eat through the colder months. Both will grow happily whether you sow seed under cover in the greenhouse or plant young plants out in a raised bed.
Growing courgettes and squash in the greenhouse
|
When to sow seed |
When to plant out |
When to harvest |
Seed depth |
Space needed between crops |
Light preference |
|---|---|---|---|---|---|
|
Mid-April to May, at 18 to 21C |
Early June, after the last frost |
Courgettes Jul to Oct; squash from autumn |
2cm |
Courgettes 90cm; winter squash up to 1.5m |
Full sun |
A greenhouse or other cover gives courgettes and squash the warm, reliable start they love. Both are tender plants that hate the cold, so sowing under glass means stronger seedlings, better germination, and young plants kept out of reach of slugs until they are big enough to cope. Think of the greenhouse as a nursery rather than a permanent home, though: these plants grow huge and will quickly swamp a greenhouse border, so raise them under cover, then move them outside. Even a compact patio greenhouse is plenty for getting a batch of plants going.
Growing from seed
Growing from seed is the cheapest route and gives you the widest choice of varieties, from compact bush courgettes to trailing winter squash and pumpkins. Knowing when to sow courgette seeds in the UK is the main thing to get right: sow indoors from mid-April to May, early enough for a long season but late enough that the plants will not outgrow their pots before it is warm enough to plant out.
Sow the seeds individually on their edge (not facing up or down!), about 2cm deep, in 7.5 or 9cm pots or modular seed trays of moist, peat-free compost. Setting each seed on its side rather than flat helps stop it rotting before it sprouts. They need warmth to germinate, ideally 18 to 21C, so a heated propagator or a bright windowsill is ideal. One seed per pot keeps the roots undisturbed, which these plants prefer. It is worth sowing a few spares in case some fail, then giving away any extra plants you do not need.
Keep the pots somewhere bright and warm, and water them regularly without letting them sit soggy. Greenhouse shelving or a seedrack lifts your trays up off a cold floor and into the best of the light, which the seedlings need to grow into sturdy, stocky plants rather than leggy ones. Stand the pots on the staging while they grow on, and pot up into a slightly larger container if they outgrow their first pot before planting time.
Once the seedlings have a couple of sets of true leaves and the last frost has passed, harden them off so they get used to life outdoors. Move them out during the day and back in at night for a week or so, or use a cold frame to do the job for you, before planting them in their final spot in early June.
Growing from young plants
If you do not have the time, space or warmth to raise plants from seed, buying young plants is an easy shortcut. Garden centres and online nurseries sell courgette and squash plug plants through late spring and early summer, ready to grow on. The choice of varieties is narrower than with seed, but the convenience is hard to beat, and one or two plants is often all you need.
Buy your plants once the worst of the cold has passed, and check they have been hardened off, or do it yourself over a week. Prepare the planting site well in advance: dig a generous bucketful of well-rotted manure or garden compost into each spot, water it well, and choose a warm, sunny, sheltered position. Plant out in early June once all danger of frost has gone, firm each plant in gently and water well. Keep new plants well watered while they settle, and collecting rainwater in a water butt gives you a free, plentiful supply for thirsty plants through summer.
When and how to harvest
Courgettes are ready surprisingly fast, usually from July, and the golden rule is to pick them young and often. Cut the fruits at around 10 to 15cm long, while they are tender and full of flavour. Regular harvesting keeps the plant cropping: leave fruits on and it slows down, but keep cutting and it will carry on producing right through to the first frosts in October.
Top Tip: Use a sharp knife or secateurs and check every few days in warm weather, as courgettes can double in size almost overnight.
Winter squash and pumpkins work the other way around. Rather than picking them young, you leave the fruits on the plant through late summer and autumn to swell and ripen fully, harvesting them before the frosts arrive. We will cover storing them properly in the raised bed section below, as the principles are the same wherever you grow them.
Growing courgettes and squash in raised beds (from seed and plants)
|
When to sow seed |
When to plant out |
When to harvest |
Seed depth |
Space needed between crops |
Light preference |
|---|---|---|---|---|---|
|
Late May to early June |
Plant out early June, after frost |
Courgettes Jul to Oct; squash from autumn |
2cm, sown on edge |
Courgettes 90cm; winter squash 1.5 to 2m |
Full sun and a sheltered, warm spot |
Courgettes and squash are hungry, thirsty plants, which makes them a natural fit for a raised bed filled with rich, moisture-retentive soil. A raised bed lets you build exactly the deep, fertile, compost-heavy soil these plants crave, warms up a little earlier in spring, and keeps the sprawling plants in their own dedicated space.
When to sow and plant
You have two routes with a raised bed. The first is to sow indoors from mid-April to May, as described above, then plant the young plants out in early June once the frosts have passed. The second is to sow the seed straight into the bed in late May or early June, once the soil has warmed up, with a cloche or fleece over the top for the first few weeks. Sowing in situ skips the transplanting, but plants started this way crop a little later than those raised early under cover. Our monthly seed sowing guide is handy for keeping the rest of the veg patch on track at the same time.
Where to position your bed
Courgettes and squash are sun-lovers, so pick the warmest, brightest, most sheltered spot you have. Full sun helps the fruits set and ripen, and shelter keeps the big, soft leaves from being shredded by wind. Bear in mind how much room these plants take up: a courgette forms a large, bushy plant, while trailing winter squash and pumpkins will scramble for a couple of metres in every direction.
Give them space to sprawl, or train climbing squash varieties up a sturdy support to save ground, supporting heavier fruits in nets as they swell.
Watering, soil, spacing and seed arrangement
Soil: these are greedy feeders, so the richer the bed, the better the crop. Before planting, dig plenty of well-rotted manure or garden compost into each planting station, ideally a good bucketful per plant. A thick mulch of compost over the surface after planting helps lock moisture into the soil and keeps weeds down, just leave a small gap around each stem to stop it rotting.
Spacing and arrangement: spacing is where courgettes and squash differ most. Space courgettes and bush types at least 90cm apart. Trailing winter squash and pumpkins need much more room, up to 1.5 to 2m apart, or train them vertically with canes to claw back some space. When sowing direct, sow one or two seeds per station, on edge and about 2cm deep, then remove the weaker seedling if both come up. Sow or plant into the centre of each space so the plants can spread out evenly in all directions.
Top Tip: Courgette plants can get very big and take over a space. Once established, don't be afraid to chop some of the stems. This allows the energy to go to the flowers and fruits but also keeps the plants from taking over the area.
Watering and feeding: courgettes and squash are thirsty and need regular, generous watering, especially once flowering and fruiting. Water at the base of the plant rather than over the leaves, which helps prevent powdery mildew, and avoid soaking the soil right against the stem, which can cause it to rot.
Top Tip: A clever trick is to sink a pot into the soil next to each plant and water into that, sending the water straight to the roots.
Plants in rich ground do not usually need feeding, but a high-potash feed such as a tomato feed every ten to fourteen days once the first fruits start to swell will keep heavy croppers going. Our month-by-month raised bed guide sets out the seasonal jobs in more detail.
A quick note on pollination
Courgettes produce separate male and female flowers, so a pollinator needs to visit both before fruit can grow. Sometimes the plants need a helping hand and require hand-pollination for this to happen. It's a good idea to pick the male flower, strip back the petals, and gently dab the pollen onto the centre of the female flower to help the fruit set.
How do you know if its a male of female flower? A good rule of thumb: if you look at the flower and can see what's basically a baby courgette already forming behind it, that's your female.
Female courgette flower
Courgette and squash companion plants
Courgettes and squash respond well to good companion plants. The classic pairing is the Three Sisters, where squash grows alongside sweetcorn and climbing beans: the corn supports the beans, the beans feed the soil, and the squash leaves shade the ground and keep weeds down. Beans and peas make useful neighbours generally, as they fix nitrogen for these hungry plants. Flowers such as nasturtium, marigold and borage draw in the bees and hoverflies that pollinate the blooms, and nasturtium can lure aphids away as a trap crop. The same family grows happily nearby, so cucumbers make natural bedfellows.
It is worth knowing what to keep apart too. Avoid planting courgettes and squash right next to potatoes, which compete heavily for water and nutrients and can encourage disease, and keep them away from other members of the cucurbit family if you are saving seed, as they cross-pollinate freely. Strong-smelling herbs and aromatic plants are generally a safe bet around the edges of the bed.
Courgette and squash pests and problems and how to avoid them
Courgettes and squash are largely trouble-free, but a handful of problems crop up often enough to be worth knowing, and most can be headed off with good care rather than chemicals.
Slugs and snails are the biggest threat early on, stripping tender young seedlings overnight in a mild, damp spring. This is the best reason to raise plants under cover and only plant them out once they are large and robust. Protect new plants with your preferred organic slug control, encourage natural predators such as birds, frogs and ground beetles, and keep the area tidy so there are fewer hiding places.
Powdery mildew shows up as a white, dusty coating on the leaves later in summer, often when plants are dry at the roots. Keep plants well watered and mulched, water at the base rather than over the foliage, and remove badly affected leaves to improve airflow. It rarely kills an established plant but can shorten the season if left unchecked.
Poor pollination, leading to no fruit or fruitlets that rot and shrivel when small, is common in early summer. It is usually just down to cool weather keeping the pollinating insects away, and tends to sort itself out as things warm up. If you want to give nature a hand, you can hand-pollinate: pick a male flower (the one on a plain stalk, with no baby fruit behind it), peel back its petals and dab the pollen into the centre of the female flowers (the ones with a tiny fruit behind the bloom). Planting plenty of bee-friendly flowers nearby helps too.
Cucumber mosaic virus can affect the whole cucurbit family, causing mottled, yellow, distorted leaves and stunted plants. There is no cure, so remove and dispose of affected plants promptly to stop it spreading, control the aphids that carry it, and choose resistant varieties where you can. Aphids themselves are easily dealt with by squashing colonies by hand or encouraging ladybirds and hoverflies into the garden.
Cooking with courgettes and squash
The real joy of growing these crops is eating them, and the challenge in a good year is keeping up with the glut. Young courgettes are wonderful simply sliced and fried in butter or olive oil, griddled, or grated raw into salads, while winter squash and pumpkin come into their own roasted, in soups and in slow-cooked dishes. A couple of Rhino recipes make the most of a squash or pumpkin harvest:
When the courgettes come thick and fast, keep picking and keep cooking: they do not store for long, so eat them within a few days, give the surplus away, or turn a glut into soups, fritters and chutneys for later. Winter squash, by contrast, keep for weeks once cured and stored. If you have caught the growing bug, our guides to growing cucumbers and growing tomatoes cover two more greenhouse favourites, and our how to grow asparagus guide is well worth a look for a perennial crop to plant alongside them.
Few crops are as forgiving or as rewarding for the effort as courgettes and squash. Give them rich soil, plenty of water and a sunny spot, keep picking the courgettes young, and let the squash ripen for winter, and one or two plants will keep your kitchen busy from midsummer well into the colder months.