How to Grow Butternut Squash

Butternut squash is one of my very favourite vegetables of all. Whether it’s gently roasted in the oven, or turned into a delicious warming soup on a winter’s day, the richness and flavour really is unrivalled.

Even better, over the last few years of experimentation I’ve found that it’s surprisingly easy to grow your own butternut squashes. In early autumn each year there is little more exciting than harvesting a huge collection of delicious, organically-grown squashes. Stored correctly they’ll last for months on end, meaning that you can enjoy almost year-round butternut squash for minimal effort.


Growing Butternut Squash from Seed


The easiest way to grow butternut squash is to purchase some seeds.

There are a number of different varieties available. The most popular of these, and the type of butternut squash sold in supermarkets, is known as “Waltham Butternut”.

Butternut squash seeds are surprisingly easy to germinate, with no special skills required. Simply pop them into a pot of good-quality compost, water well and cover to keep the moisture in.

The seeds tend to germinate most quickly when they’re kept warm, so placing them on a sunny windowsill or in an airing cupboard can be beneficial. Butternut squash are best planted in the spring time – typically March or April. This way they’ll have time to grow into good-sized seedlings in time for planting out in May or June.

When planting butternut squash seeds the most important factor to consider is that these seedlings grow rapidly and can become giants in a matter of weeks.

This is important, because it is worth planting butternut squash seeds in good-sized pots, with just a handful in each. As a general rule I plant 3-4 seeds into a 5″ flower pot. This way, as the seedlings germinate and begin to grow they don’t crowd each other out too quickly.

Transplanting Seedlings

The bigger and healthier your seedlings are when you plant them out the better. Butternut squash plants will start to die off in late summer or early autumn, so the quicker they can get growing the longer they’ll have. As long seasons mean more (and larger) squashes it makes sense to give them the best possible start.

Once seedlings have their first couple of proper leaves it can therefore be a good idea to transplant them individually into large pots. This gives them plenty of room, plus additional nutrients from the new compost. The goal is to have good-sized bushy plants by the end of May, ready to plant out in their final growing position.

Planting Out


When the last frosts have passed it is safe to plant out your butternut squash plants.

Here a few tips can come in handy. Squash plants grow large and require good quality soil with plenty of nutrition for best results. Therefore you should plan ahead and set aside a good-sized section of your vegetable plot for these plants. Aim to plant your seedlings out with 24″ or more between plants to give them space to grow.

Butternut squash plants like the sunniest position you can give them, and aim to enrich the soil once a month with a good quality fertilizer.

One of the most noticeable things about planting butternut squash is that the plants can take some weeks to get established. The first time I ever grew squash I planted out my lovingly-tended seedlings only to sit and watch them do nothing for the first month. They seemingly didn’t grow at all, obstinately sitting there refusing to do anything. Over the years I have found this to be quite normal, so don’t fret!

The downside of this “lag phase” is that having placed them into a generously-sized part of your vegetable plot you can find yourself furiously weeding around your plants each week, while the squashes themselves refuse to grow. For this reason planting through weed control matting can be a useful idea, as it minimizes the weeding that you’ll need to while waiting.

With enough nutrition and patience, one day you’ll suddenly find that your squashes have begun to produce extra leaves. This is when the fun really starts.

Maintaining Your Plants

Butternut Squash

Not only are butternut squash plants big in dimensions but they can grow at an astonishing rate! Once that spurt happens you can almost see them growing before your very eyes! Soon enough that bare soil will be fully covered in attractive foliage and your squashes send out runners in all directions. The benefit of this is that soon enough your plants will cover all the available soil, drowning out any weeds that are trying to establish themselves.

Once your butternut squash plants have started to grow rapidly they will require minimal effort. Little weeding is required, and few pests and diseases seem to affect them. Indeed, in terms of maintenance there are really only three core tasks.

Watering – Butternut squash plants can be quite thirsty; their rate of growth can be directly related to the amount of water they receive. On hot summers days it is therefore worth the time-investment to give them a really good soaking in the morning before the sun gets too intense. Building up some soil around the seedling to produce a small “wall” around your seedling will help direct the water straight to their roots, rather than just soaking into the soil around them.

Feeding – More nutrients means better growth. The use of a water-soluble to granulated fertilizer can also be a beneficial addition, though is by no means essential if you’re strapped for time.

Controlling – Butternut squash plants grow so quickly that the biggest task of all can be trying to control the plants to prevent them taking over your garden!. I use twigs to carefully “peg” the plants and redirect their runners away from my other crops.


Butternut squash

Once your plants gain a decent size you will likely start to see their beautifully simple yellow flowers opening. Soon afterwards the first hints of fruit will be seen. These initially look like tiny “light bulbs” but grow over time into fully-formed fruits.

These fruits can be left on the ground to develop, though many experienced gardeners carefully place a blanket of straw underneath them. This reduces the risk of the under-surface rotting if it comes into regular contact with damp soil.

Harvesting Butternut Squashes

Day 277: Butternut

One of the difficulties with growing butternut squashes is deciding when they’re ripe. With their thick skins butternut squashes don’t go soft or change colour when they’re ripe, so how do you know when its time to harvest them?

Here there is a simple solution that seems to work like magic. In early Autumn, as the season draws to a close, you’ll find that your butternut squash plants start to slowly due off. Leaves will change colour and drop off, and over time you’ll see your once-verdant squash patch become ever more bare, eventually leaving just the stems of the plants and the fruits.

I have found that this is the best possible time to harvest, when the fruits have had as ,long as possible to ripen and absorb all their sugar. These days, therefore, I wait until my plants look like they’re turning, and then harvest all my squashes in one go.

Harvesting butternut squashes isn’t as easy as you might think. Given a long growing season the stems of your fruits will be thick and tough. More often than not I use either secateurs, or for really thick stems a saw, to cut them off the plants.

As a handy tip, don’t cut the stems too close to the fruits. Doing so will reduce how long they can be stored for. I aim to cut fruits off with several inches of stem attached, and they will then store in perfect condition for months on end. Removed in this way its is very unusual not to have healthy fruits to enjoy long after Christmas.

Storing Butternut Squashes

Squash (butternut)

One of the real benefits of growing butternut squashes is just how long they will last for. There are two strategies which can be used to keep your squashes in good condition for as long as possible.

Firstly the whole fruits – with the generous length of stem attached – can be placed in a cool and dry area. Consider placing them in your shed or garage as good options. The fruits should not be allowed to touch, and air movement is important to stop them rotting. I expect that fruits kept in such a way will last for at least three months, and often twice that time.

Simply check them once every few weeks to check they’re in good condition. Any which are going soft or seem to be going wrinkly should be used sooner, while perfect specimens can be left for later.

Freezing Butternut Squash

Butternut squash

A second option for storing butternut squash is to freeze it. While the process takes some time it means that you’ll always have butternut squash ready for use at any time.

Start off by cutting the end off your squash. Then turn it on end and gently cut the skin off by running a sharp knife down the sides. Once skinned, cut in half, scoop out the seeds and dice into chunks of roughly 2″ square. A little bigger or smaller won’t make a massive difference. Now you need to get prepared.

You’ll want two pans; one filled with ice water, and one filled with boiling water.

Place the pan of hot water on the stove and bring to the boil. When the water starts bubbling add your squash and start timing. After five minutes remove the squash and dunk it into the ice water.

This process does two things. Firstly, the short boiling period helps to remove chemicals that can cause squash to spoil. The ice water stops the cooking process dead.

Once your squash is cold to the touch, leave it to dry before bagging and placing into your freezer.

Now, whenever you fancy butternut squash you can simply defrost it in the microwave (or in hot water) and then cook as you normally would.

Saving Butternut Squash Seeds

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One of the beauties of growing butternut squash is that each individual fruit produces so many seeds. In other words, if you’re smart you’ll only ever need to buy a single packet of seeds. From then on you can save a handful of seeds each year to start you off again the following spring.

Saving the seeds is surprisingly easy. Start off by scooping the seeds out of a fruit. Unfortunately these will be all “slimy” and will have bits of squash flesh on them. Next, therefore, I like to place them into a plastic bottle, add some water, and shake the seeds vigorously. Replace the water and follow the same process. Keep going until the water remains clear, which can take several attempts.

Finally, when the seeds are free of squash flesh they can be laid out thinly on a tray to dry. I find a sunny windowsill tends to work well. Keep an eye on them while they’re drying, turning them once or twice a day, to prevent the undersides of the seeds remaining damp and attracting mould.

Once the seeds are dry they can then be stored away for the next year in an labelled envelope. In this manner i have found that seed can remain viable for years on end – so even a single decent crop can keep you in butternut squash seeds for years to come.

So there you go – the art and science of growing butternut squash. In many ways the perfect vegetable to grow; delicious, low maintenance and willing to produce vast quantities of food for very little effort.

Growing butternut squash is one of the easiest things possible when you follow some simple rules. If you're wondering how to grow butternut squash then this detailed guide shows you everything you need to know. A must-read article for all gardeners, even for beginners at growing vegetables.

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