Cucurbita maxima 'Crown Prince F1' is a Half-Hardy Annual and one of the most highly regarded winter squashes in British horticulture. It is a vigorous trailing vine that requires a long growing season and generous space, but rewards that investment with large, magnificently flavoured fruits of remarkable keeping quality.

What Makes F1 Different: This is an F1 hybrid variety, meaning it is produced by crossing two carefully selected parent lines. The result is a plant with enhanced vigour, greater disease resistance, and highly uniform fruits compared to open-pollinated Crown Prince varieties. It germinates reliably, grows vigorously, and produces fruits that are consistently large, well-formed, and of excellent eating quality — making it particularly well suited to UK conditions where the growing season can be unpredictable.

The Blue Skin Explained: The unique silvery blue-grey skin of Crown Prince is caused by a natural waxy bloom — a thin layer of epicuticular wax deposited on the surface as the fruit matures. This wax coating is not merely decorative; it acts as a natural barrier that slows moisture loss and dramatically extends storage life. The skin hardens to an almost impenetrable shell at maturity, which is why Crown Prince stores so remarkably well.

Crown Prince needs a long growing season to develop its large, deeply flavoured fruits — sowing indoors in April gives it the full British summer it needs to mature before the first frosts of autumn.

How to Sow:
Sow indoors from mid-April to mid-May. Sow seeds individually into 7–9cm pots of good-quality seed compost, placing each seed on its edge approximately 2cm deep. Sowing on the edge prevents the seed sitting in a pool of moisture at its base, which reduces the risk of rotting. Maintain a temperature of 18–21°C. Germination typically occurs within 7–10 days. Grow on in a bright, warm spot and water carefully — overwatering at the seedling stage is the most common cause of failure.

Transplanting:
After the last frost has passed — typically late May to early June across most of the UK — harden plants off gradually over 7–10 days before planting out. Space plants 1–1.5m apart; Crown Prince is a vigorous vine that will spread generously given the room. Prepare the planting hole generously with well-rotted manure or compost, as this is a hungry, thirsty crop that will repay good soil preparation handsomely.

Ongoing Care:
Water deeply and consistently at the base of the plant, keeping the foliage dry to reduce the risk of powdery mildew — a common issue in warm, dry summers. Once the first fruits have set and reached the size of a tennis ball, begin feeding weekly with a high-potassium tomato-type fertiliser. For the largest and best-quality fruits, limit each plant to two or three by removing surplus female flowers once your chosen fruits are well established. The vines can be trained along the ground or encouraged over a sturdy arch or fence — growing vertically saves space and keeps fruits off damp soil, improving their keeping quality.

Harvesting:
Harvest from September to October, once the skin has turned fully blue-grey and hardened completely, and the stalk has begun to dry and cork. Leave as much stalk as possible — at least 5cm — as this is the primary entry point for storage rots. Cure in a warm spot at 25–30°C for 10–14 days before moving to long-term storage. Stored in a cool, dry, frost-free place, Crown Prince F1 will keep for an outstanding 4–6 months.

Crown Prince is a hungry, spreading plant that thrives with good companions around it — these from our range protect the crop, support pollination, and make the vegetable garden look as beautiful as any flower border:

• 🌼 Nasturtium 'Tom Thumb': The Squash's Bodyguard. Nasturtiums are one of the most time-honoured companions for squash — their pungent foliage confuses and deters aphids and whitefly, and they serve as an outstanding trap crop, drawing blackfly away from the vulnerable squash vines onto themselves. Their vivid orange and red flowers also bring colour to the vegetable garden throughout the long months while Crown Prince is quietly developing its fruits, and the edible leaves and flowers make a peppery, beautiful garnish alongside roasted squash.
• 🧡 Calendula 'Art Shades Mixed': The Potager Classic. The warm apricot and amber tones of Art Shades Calendula provide a beautiful colour contrast to Crown Prince's cool blue-grey fruits in the autumn garden. As a companion, Calendula is exceptional — it attracts beneficial hoverflies and lacewings that prey on common pests, and its resin-coated roots are believed to actively deter soil nematodes. A plant that earns its place as much for what it does as for how it looks.
• 🌼 Borage: The Pollination Specialist. Borage is arguably the single most important companion you can plant alongside any squash. Poor fruit set — where flowers appear but no fruits develop — is almost always caused by insufficient pollination, and a clump of Borage nearby creates a constant stream of bees working the area throughout the day. Its electric blue flowers are also edible with a fresh cucumber flavour, and make a striking garnish alongside Crown Prince soup. Plant it at the edges of the vegetable bed and let it do its work quietly all season.
• 🌿 Basil Classic Italian: The Aromatic Deterrent. Basil planted near squash is a classic Italian kitchen garden practice — its powerful aromatic oils are believed to confuse and deter the aphids, spider mites, and whitefly that target squash foliage during warm spells. On the plate, the pairing is equally compelling: roasted Crown Prince with good olive oil, Parmesan, and torn fresh basil is one of the great autumn dishes, and growing both together means the ingredients arrive in the kitchen at exactly the same time.

Sow indoors in April for a long, productive growing season — Crown Prince F1 needs the full warmth of the British summer to develop its large, dense fruits before the first frosts arrive in autumn.