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How to Grow Butternut Squash

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Growing butternut squash is deeply rewarding; the squash you produce will happily last through most of the winter. However, it does require ongoing care throughout it’s growing season, so if you are a ‘plant if and forget it’ type of gardener, they may not be for you.

Butternut Squash Varieties

butternut squash

Butternut squash is a type of winter squash and a relative of zucchini and cucumber. Growing butternut squash is a great project for a novice gardener who is willing to put a little effort into growing them. 

Harrier butternut squash is probably the most recognized variety, with its tough, golden skin and bulbous shape. Butterbush butternut squash is a smaller variety of butternut squash and is ideal for those who have limited space or would like to grow in a container, rather than in beds. There is also Barbara butternut squash, which is striped green and orange. Its rounder shape yields more flesh than other varieties. This is also an ideal variant for growing in pots and containers.

Some varieties of the butternut squash plant are trailing and better suited to growing in a vegetable plot in raised beds, while other, more compact varieties can be grown successfully in pots. The trailing squashes can put out up to 15 feet long trails, so ensure you have enough space between other plants to avoid overcrowding and ensure adequate ventilation at ground level.

How to Grow Butternut Squash From Seed

Quite possibly the easiest seeds to find in fall, when, along with pumpkins, they are there to be had from the kitchen. Save yours from the compost pile and try planting them out instead. You will need to clean and dry any kept seeds indoors as thoroughly as possible before you can plant them.

It’s called “winter squash” because that’s when you harvest it – but you’ll need to plant it in the spring! Plant butternut squash outside only when any chance of frost has passed and spring has begun to warm the soil – late April or early May is normally perfect. Ideally, start growing butternut squash seeds indoors, either in a greenhouse or conservatory, before the young shoots are placed in a cold frame to harden off, then planted outdoors when the weather is sufficiently warm. Once outside, plant and cover young shoots with clear plastic cups or glasses to help retain heat and encourage growth. Planting butternut squash unprotected could lead to poor growth or die-off.

Raise some soil in the area you are planting your squash, and ensure your soil is well-fertilized. Plant your seeds around an inch deep and keep the soil moist. Add compost if you wish. Take care not to over-water, as they do not appreciate a soggy environment and can be prone to mold and mildew. Sow the seeds on their side, rather than upright, for best success.

When they are starting to shoot, mark them each with a cane in the ground as they will spread out through the summer, and you will need a marker for where to water. You should expect it to take around 110-140 days for the plants to fully mature.

Feed regularly through the entire summer with fertilizer as they require a rich, nutrient-dense environment. You will need to feed a potash-rich fertilizer around every 10 – 14 days. Roots of the butternut squash are shallow, so take care when weeding the surrounding area not to damage them.

When the shoots are still young take particular care when watering, and even when they are established, it is advisable to water around them, rather than directly on to them.

Ideal Conditions for Butternut Squash

Butternut squash likes to grow in warm and sunny conditions. It will need a sunny spot that enjoys full sun and a light, well-drained soil to flourish. Make sure to add lots of manure and compost to the site before planting, Mix it in well and let it sit for at least a few days before planting or transplanting outside. If starting your seeds off indoors, be ready to plant out in your garden by the end of May at the latest. If you are growing your squash in a bed with other vegetables, they make a great companion plant for sweetcorn.

Powdery mildew can affect butternut squash. Signs to look out for is a white, powdery dust on the leaves and signs of stunted growth. If this happens, check to ensure that you are giving sufficient water and check that nitrogen levels are not too high as a result of over-fertilizing. Prune back where possible to increase airflow and ventilation.

When the squash have arrived, keep a close eye out for slugs and snails.

How to Grow Butternut Squash in Containers

If you are planning on planting butternut squash plants in a container, you will either need a large container or choose a more compact variety (such as the Barbara). Fill your container with rich, well-fertilized soil and place one seed per pot on its side, around an inch below the surface. If planting in a much bigger container, you can plant more than one seed, but take care not to overcrowd them. 

Start them indoors, around 6-8 weeks before the end of any winter frosts. Find a warm and sunny, well sheltered location in the garden to situate them. Once the main shoots are around 60cm long, cut back closely to help encourage fruit production and flowering. Encourage pollinators such as bees to the area, as these will pollinate your butternut squash flowers.

Harvesting Butternut Squash

Ideally, leave butternut squash out on the vines for as long as possible before any frost (ideally late October). This gives the skin chance to harden off and ensure your squash are usable through winter.

Butternut squash uses

Butternut squash is a versatile vegetable, thanks to its thick and filling texture. It is ideal roasted as a side dish, or in soups and stews and makes a great choice for many Asian dishes, such as curries. It’s high levels of carbohydrates make it a nutritious choice. It is also high in potassium, beta-carotene and iron.

Butternut squash storage

When you have harvested your butternut squash at the end of the season, store in a cool, dry place such as a garage or cellar, where they will keep through much of winter to be used throughout the season. 

Other Questions About Butternut Squash Growing

How many squashes do you get from one plant?

This will depend upon the size of the plant and the conditions it is planted in, but you should get at least 2-3, and sometimes quite a few more. You will often notice butternut squash growing a large number of fruit, only to see some drop off when they are still small. This is normal – the plant is often best at figuring out how much fruit it can produce.

Can you grow butternut squash on a trellis?

You can grow squash vertically, but this is often better with smaller summer squashes. Winter squash varieties are often too heavy and may need significant extra support to help bear their weight.

Can you grow butternut squash on your compost pile?

You might have seen butternut squash growing on compost heaps – and it is possible. Try it if space in your garden is at a premium, but remember, you’ll need to keep the compost there until the produce is harvested, which might not be ideal.

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