Growing Butternut Squash: A Complete Guide to Planting, Caring & Harvesting

Introduction

If you’re looking to grow a delicious, versatile, and long-storing vegetable in your allotment or garden, butternut squash is an excellent choice. With its sweet, nutty flavour and creamy texture, it’s perfect for soups, roasts, and even desserts. But to enjoy a bumper crop, you need to know how to plant, grow, care for, and harvest butternut squash the right way.

In this complete guide, we’ll take you through everything you need to know—from seed to plate. Whether you’re a beginner gardener or an allotment pro, follow these proven tips for growing butternut squash successfully in the UK.

What Is Butternut Squash?

Butternut squash (Cucurbita moschata) is a winter squash variety with a distinctive elongated pear shape and pale tan skin. The flesh is orange, dense, and sweet, making it a favourite in both savoury and sweet dishes. Unlike summer squash, butternut squash is harvested in autumn when fully mature and has a long storage life.

Choosing the Best Variety of Butternut Squash to Grow

There are several butternut squash varieties available for UK growers:

• Hunter F1 – A compact, early-maturing variety perfect for smaller spaces and cooler climates.
• Waltham Butternut – A traditional variety known for its reliability and excellent flavour.
• Butterbush – Great for container growing and small allotments.

Look for varieties that mention “early maturing” or “suitable for cooler climates” on the seed packet if you’re in the UK.

When to Plant Butternut Squash in the UK

Butternut squash is a warm-season crop, so timing is crucial.

• Sow seeds indoors: April to early May
• Transplant outdoors: Late May to early June (after the last frost)
• Harvest: September to October

Starting seeds indoors gives them a head start, especially in cooler regions.

How to Grow Butternut Squash from Seed

1. Sow Indoors

Start seeds in 7cm pots filled with seed compost. Sow each seed on its side about 2cm deep.

2. Warmth Is Key

Place pots in a propagator or warm windowsill. Ideal germination temperature is 20–25°C.

3. Harden Off

Before transplanting outdoors, harden off the plants gradually over 7–10 days.

Where to Plant Butternut Squash

Choose a sunny, sheltered spot with well-drained, fertile soil.

• Soil preparation: Add plenty of organic matter, like compost or well-rotted manure.
• Spacing: Give each plant 90–100cm of space in all directions.
• Support (optional): If space is limited, train plants up a strong trellis.

Growing Butternut Squash in Containers

Yes, you can grow butternut squash in large containers!

• Pot size: At least 40–50cm wide
• Soil: Rich, well-draining compost
• Watering: Keep evenly moist
• Feeding: Use a high-potash liquid feed every 10–14 days once fruits start forming

Choose compact varieties like Butterbush for the best results in containers.

How to Care for Butternut Squash Plants

1. Watering

Water regularly, especially during dry spells. Aim for deep watering once or twice a week rather than light watering daily.

2. Mulching

Mulch around plants to retain moisture and suppress weeds.

3. Feeding

Feed every 2–3 weeks with a potassium-rich fertiliser like tomato feed when fruits start to develop.

4. Pollination

Butternut squash has male and female flowers. Bees do most of the pollination, but you can hand-pollinate using a soft brush for better yields.

Common Butternut Squash Pests and Problems

1. Slugs and Snails

Attack seedlings and young plants. Use organic slug pellets or beer traps.

2. Powdery Mildew

Common in late summer. Avoid overhead watering and improve air circulation.

3. Poor Fruit Set

Can happen due to poor pollination or cold weather. Hand-pollinate or wait for warmer, drier conditions.

How to Support and Train Butternut Squash

Butternut squash plants sprawl but can be trained vertically to save space.

• Use strong trellises or garden arches.
• Tie stems gently with soft ties.
• Support heavy fruit in slings made of old tights or fabric strips.

Vertical growing also reduces pest and disease issues by improving air circulation.

Harvesting Butternut Squash

Harvest before the first frost when the skin is hard and tan-coloured, and the stem has dried and turned corky.

• Use secateurs to cut the squash with a few inches of stem attached.
• Leave them in the sun or a greenhouse to cure for 10–14 days to improve flavour and storage life.

Storing Butternut Squash

Store in a cool, dry, frost-free place like a shed or pantry.

• Ideal temperature: 10–15°C
• Storage life: 2–4 months
• Inspect regularly for rot or soft spots

How Many Butternut Squash Per Plant?

On average, you’ll get 3–5 squash per plant, though compact varieties may yield slightly fewer. Proper feeding, pollination, and watering will increase your crop.

Companion Planting for Butternut Squash

Good companions:

• Sweetcorn – provides vertical structure
• Beans – fix nitrogen
• Nasturtiums – attract pests away

Avoid planting near potatoes or brassicas to prevent competition and disease.

Conclusion

Growing butternut squash is incredibly rewarding, offering tasty, nutritious results that store well into winter. Whether you’re growing on an allotment or in containers, follow the tips above to ensure healthy plants and a successful harvest. With the right preparation and care, you’ll enjoy delicious butternut squash long after the growing season ends.

Top 10 Questions and Answers About Growing Butternut Squash

1. When should I plant butternut squash in the UK?

Sow indoors in April and plant out in late May or early June after the last frost.

2. How long does butternut squash take to grow?

Typically 90–110 days from sowing to harvest.

3. Can I grow butternut squash in pots?

Yes, choose a large container and compact variety like Butterbush.

4. How much sun do they need?

Full sun—at least 6–8 hours a day.

5. How often should I water butternut squash?

Water deeply once or twice a week, more often during hot, dry spells.

6. Do I need to hand-pollinate my plants?

Only if pollinators are scarce. Use a soft brush to transfer pollen.

7. Why are my squash not forming properly?

Likely poor pollination or irregular watering. Ensure steady moisture and consider hand-pollination.

8. Should I prune my butternut squash?

Not essential, but removing excess leaves can improve airflow and reduce disease.

9. How do I know when butternut squash is ripe?

The skin turns a solid tan colour and is hard to the touch; the stem will be dry and corky.

10. How should I store butternut squash after harvest?

Cure for 10–14 days in a warm spot, then store in a cool, dry place.