Winter squash come in many different shapes, sizes and colours, says Miranda Kimberley Squash is a term that can be applied to vegetables (technically fruit) including courgettes, marrows, pumpkins and butternut squash. This is because it is an umbrella term for four species in the cucurbit family.

C. maxima 'Waltham Butternut' - image: Floramedia
C. maxima 'Waltham Butternut' - image: Floramedia

Cucurbita pepo covers the widely grown courgettes and marrows, also referred to as summer squash, as well as most pumpkins and acorn squash. Most people know the straight green varieties of courgette from the supermarket, but they also come in different colours and shapes — round fruits and even flying-saucer shapes.

Butternut squash is derived from C. moschata. C. mixta is known as cushaw squash and the widely cultivated C. maxima includes some varieties of prize pumpkins, the
hard-fleshed hubbard squash and buttercup squash.

As courgettes and marrows are pretty well known, this article focuses on those fruits known as winter squash because they are harvested late in the year and stored over winter until eaten. There will also be reference to pumpkins, often grouped with winter squash.

Winter squash and butternuts are very varied in shape, size and colour. Most varieties tend to be vigorous trailing plants. They can be allowed to scramble up a trellis or netting or can be kept tidy by being cut back. These squashes, which are later to flower and fruit than summer squash, are allowed to mature, harvested before the first heavy frost  and then dried off and stored in a frost-free shed.

Pumpkins come in a range of fruit sizes. They are mainly used at Halloween for carving into lanterns. Though they are used to make pumpkin pie, most cooks find winter squash have a better taste for pie use. Pumpkins are generally more coarse fleshed than squash and do not store for such a long period.

Squashes are easily raised from seed and can be sown outdoors in the spot where they are to grow in late May or early June, or they can be started off indoors in pots earlier in April. When planting out, they need a sunny spot, plenty of organic matter and a well dug hole. The vigour of each vine varies, but in general give winter squash at least 90cm of space apart from each other. Use cloches over young plants on cold nights.

They should be watered regularly but the neck of the plant and leaves should be avoided to prevent rotting and diseases. Feed every 10-14 days with a high-potash liquid fertiliser once the first fruits start to swell. To protect the fruit of marrows and pumpkins until they are harvested, simply slip a tile or piece of glass underneath them.

They should be harvested as late as possible — only once they have a thick skin and dry stalk. Store them until late November before starting to eat them. They are tasteless if eaten fresh because they need six weeks to a couple of months to develop their nutty, sweet flavour.

What the specialists say

Kate McEvoy, partner, The Real Seed Catalogue, Pembrokeshire

"We are great squash enthusiasts. We really enjoy eating them throughout the winter and feedback from our customers is that they find them a productive and useful crop.

"Our favourite varieties are pretty much all C. maxima. They grow well in the UK climate, generally store well and have good, dense tasty fruits. We particularly like the Burgess Vine buttercup, which is ideal for growing in a smaller garden or for customers with smaller families because both the vines and squashes are reasonably small. It also has very dense, tasty flesh, ideal for roasting.

"In general, we find C. moschata varieties aren’t well suited to the UK climate. This unfortunately includes the ever-popular butternut, although we have found that one strain — the Waltham butternut — is more tolerant of cool summers. Growing for our own use, however, we prefer the vine buttercup, which is equally tasty and much more reliable.

"Our advice to customers, unless they are in particularly warm areas of the country, is to consider giving squash plants some protection either with cloches or a mini-tunnel after planting out. We grow our plants on under low hoops covered with fine-gauge mesh for as long as possible, only removing the covers once the plants start to flower."

Colin Randel, vegetable product manager, Thompson & Morgan, Suffolk

"Butternuts are probably the most popular winter squash. One excellent variety is the British-bred ‘Harrier’, which is a compact, bushy plant that produces 750g fruits some six weeks earlier than the previous US varieties that we had to grow. With them, we had to keep our fingers crossed for a long, sunny summer. ‘Harrier’ is a fantastic advert for British breeding.

"The only other popular winter squash are ‘kabocha’ types with distinctive, nutty, rich-flavoured flesh, and the ‘Crown Prince’ with its steel-grey skin and orange flesh.

"The key cultivation tip with winter squash and butternuts is to grow them through black plastic because they will reward you if their stems are kept warm — similarly as sweet potatoes and outdoor melons — and will grow, flower and fruit more successfully."

In practice

David Anderson, plant manager, Thompsons Garden Centre, Welling

"We sell several varieties of squash seeds, the majority of which are butternut squash, but our best-selling squash is still the good old pumpkin. Our most popular variety is without doubt Atlantic Giant — I guess everyone wants a giant pumpkin to carve and decorate at Halloween.

"However, our best means of selling squashes is by pre-grown varieties in a 9cm pot. We limit the range to one butternut squash, Hunter F1 — easy to grow, high yielding and good for cooking — and two pumpkins, Jack of all trades — good for Halloween — and Crown Prince — excellent for cooking.

"We have had an extensive promotion campaign over the past two years, promoting vegetable and fruit growing. Sales have rocketed due to good posters and literature readily available, explaining step by step how to grow, care for and harvest crops. Recipes and images are added to fact sheets and point-of-sale material to encourage and get the taste buds working with our customers. Who could resist a hot bowl of steaming butternut squash soup with a swirl of cream on top on a cold autumn evening?

"Another promotion we run in April is to donate a pumpkin plant to every child in our local school. This becomes part of a ‘grow the biggest pumpkin competition’. We hold a judging day at the centre that helps build local support for the garden centre and attracts an abundance of parents with spending power on a normally very quiet autumn day."

Species and varieties

Buttercup squash ‘Burgess Vine’ is considered by many to be one of the best eating squashes ever. It produces small but heavy round squashes that are dark green with a lighter-green "button" underneath. Ideal for a small garden because the vine does not take over. The squash is perfect for two or three people to eat.

Butternut squash ‘Harrier’ F1 Hybrid is a British-bred variety that produces nice pear-shaped fruits earlier than other butternuts. They are bushy plants that have an open habit, allowing the sun to ripen fruits naturally on the plant, giving added sweetness. Weight: 800g.

Butternut squash ‘Hawk’ F1 Hybrid is a fast-maturing variety with good sized fruits and sweet flesh. Produces a large crop of uniform, bulbed fruit. Weight: around 700g.

Butternut squash ‘Hercules’ F1 Hybrid produces large, sweet fruits that suit the northern European climate. They have a smaller seed cavity than Hawk F1, which means there is more flesh to eat. The vine is more compact than those on US varieties. Weight: 1.2kg.

Hubbard squash ‘Anna Swartz’ is an excellent variety for cooking. It has a large, very vigorous vine and the first ripe fruits are produced from the end of July. The fruit has sweet flesh and a hard skin, which means it is difficult to peel but keeps very well.

Pumpkin ‘Dill’s Atlantic Giant’ produces fruits weighing more than 600lbs. Sow between April and June and harvest from August to November. Excellent for Halloween lanterns and a good cooker.

Pumpkin ‘Jack of All Trades’ has a rounded shape but a flat base, making it a popular choice for carving at Halloween. It also has a rich orange skin and flesh, which makes a tasty pumpkin pie. Weight: around 4kg.

Squash ‘Blue Banana’ produces plenty of tasty fruit, which is pale blue-grey and around 2ft long. It is produced early in a season on a vigorous vine. The fruit keeps for a long time, with a waxy skin that is easily peeled off for cooking.

Squash ‘Crown Prince’ Award of Garden Merit is a blue-grey variety, shaped like a pumpkin. One of the most popular and reliable winter squashes, it has tasty orange flesh and can be stored for a long time.

Squash ‘Kabocha F1’ is a thick-skinned, dark-green kabocha squash with pale striping that has highly flavoured orange flesh. It has very good long-term storage qualities. Weight: 1.5kg.

Squash ‘Turk’s Turban’ is a trailing variety that produces a distinctively shaped fruit that makes it a popular choice for ornamental autumn displays. The fruits also have an excellent flavour for roasting, baking and cooking in soups.

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