How to Grow Squash in the UK

How to Grow Squash in the UK: Complete Growing Guide

Squash are versatile, productive vegetables that thrive in the UK with the right care. From summer squash like courgettes and patty pans to winter squash like butternut and acorn, these vigorous plants offer abundant harvests and excellent storage potential. This comprehensive guide will show you how to grow squash successfully in the UK climate.

Types of Squash

Summer Squash: Harvested young with tender skin, eaten fresh (courgettes, patty pans, yellow crookneck)

Winter Squash: Harvested mature with hard skin, stores for months (butternut, acorn, spaghetti squash, Crown Prince)

When to Sow Squash

All squash are frost-tender and need warm conditions:

• Indoor sowing: April–May in pots for transplanting (recommended for UK)
• Outdoor sowing: Late May–early June when soil has warmed and frost risk has passed
• Transplanting: Plant out in late May–early June after hardening off
• Summer squash: Can succession sow every 2–3 weeks for continuous harvest
• Winter squash: Single sowing per season

Soil Preparation

Squash are hungry, thirsty plants that need rich soil:

• Soil type: Rich, moisture-retentive but well-drained soil
• Create planting pockets: Dig holes 30cm deep and wide, fill with well-rotted manure or compost
• Mound soil: Create raised mounds for good drainage and warmth
• pH level: Slightly acidic to neutral (pH 6.0–7.0)
• Space needed: Bush types: 90cm; trailing types: 1.5–2m per plant

How to Sow Squash

Indoor Sowing (recommended for UK):

1. Use large pots: Sow in 7.5cm pots filled with seed compost
2. Sow on edge: Push seeds 2.5cm deep on their edge to prevent rotting
3. One seed per pot: Germination rates are usually high
4. Warmth needed: Keep at 18–20°C for germination (5–7 days)
5. Good light: Move to bright, frost-free location once germinated
6. Pot on if needed: Transfer to larger pots if plants outgrow before planting out

Direct Outdoor Sowing:

• Only suitable for late May–early June in warm, sheltered locations
• Sow 2–3 seeds per station on prepared mounds
• Thin to strongest seedling once established
• Protect with cloches until established

Planting Out

• Harden off: Acclimatise plants to outdoor conditions over 7–10 days
• After last frost: Plant out only when all frost risk has passed (late May–early June)
• Spacing: Bush types 90cm apart; trailing types 1.5–2m apart
• Plant on mounds: Plant at the same depth as in the pot
• Water well: Water thoroughly after planting
• Protect initially: Use cloches or fleece for first few weeks if weather is cool

Ongoing Care

• Watering: Water generously and regularly, especially when flowering and fruiting; aim for 20 litres per plant per week in dry weather
• Feeding: Feed weekly with high-potash liquid fertiliser once flowering begins
• Mulching: Apply thick mulch around plants to retain moisture and suppress weeds
• Training: Direct trailing stems in desired direction; can peg down with wire hoops
• Support fruits: Place tiles, boards, or straw under developing fruits to prevent rotting
• Restrict fruits (winter squash): Limit to 4–5 fruits per plant for best size
• Pollination: Hand-pollinate if necessary (transfer pollen from male to female flowers)

Common Problems

Poor fruit set: Often due to lack of pollinating insects or cold weather. Hand-pollinate and ensure adequate warmth.

Powdery mildew: White powdery coating on leaves. Ensure good air circulation, water at base of plants, and remove affected leaves.

Slugs and snails: Can damage young plants and fruits. Protect with barriers, traps, or organic pellets.

Rotting fruits: Caused by contact with damp soil. Raise fruits off ground on tiles, boards, or straw.

Harvesting Squash

Summer Squash:

• Harvest when young and tender (10–15cm long)
• Pick regularly (every 2–3 days) to encourage more production
• Cut with a short stem attached
• Don't let fruits mature on plant

Winter Squash:

• Timing: Harvest September–October, before first frost
• Skin test: Skin should be hard and resist fingernail pressure
• Colour: Fruit should have developed full, deep colour
• Hollow sound: Tap squash — it should sound hollow
• Dead foliage: Leaves start to die back when squash are ripe
• Cut, don't pull: Use secateurs to cut stem 5–10cm from fruit
• Cure: Leave in sun for 10–14 days to harden skin (bring in at night if frost threatens)

Storage

Summer Squash: Store in refrigerator for up to 1 week. Best eaten fresh. Can be frozen (slice, blanch, freeze).

Winter Squash: Cure for 10–14 days after harvest. Store in cool (10–15°C), dry, well-ventilated place in a single layer. Well-cured winter squash stores for 3–6 months.

Recommended Varieties

Summer Squash: Patty Pan (Custard White), Sunburst, Tromboncino, Yellow Crookneck

Winter Squash: Butternut (Waltham), Crown Prince, Uchiki Kuri, Acorn (Table Ace), Spaghetti Squash, Turk's Turban