Crown Prince squash

Sun

Full sun, ideally at least 6-8 hours of direct sunlight daily.

Water

Keep soil evenly moist, especially during flowering and fruit growth; water deeply at soil level rather than wetting the leaves.

Soil

Fertile, well-drained soil enriched with compost or well-rotted manure; slightly acidic to neutral soil is ideal.

Height

1-2 ft (0.3-0.6 m), excluding any climbing growth

Spread

10-15 ft (3-4.6 m), sometimes more in rich soil

Flowers

Large yellow-orange flowers in summer, with separate male and female flowers on the same plant.

Foliage

Large, broad, roughly heart-shaped green leaves on thick, prickly trailing stems; leaves die with frost.

Growth

Fast in warm weather.

Care needed

Medium

• Pollinators
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.5 ft (0.15 m)

2. After 1 year

   1.5 ft (0.45 m)

   full size

Full size in one season.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Growth rate

Fast

• Plant out after frost danger has passed and the soil has warmed; harden off indoor-raised plants first.
• Allow roughly 3-5 ft (0.9-1.5 m) between plants and leave room for vines to run.
• Mulch after the soil warms to conserve moisture and suppress weeds.
• Feed regularly with a potassium-rich vegetable fertiliser once fruit starts to develop, following the label rate.
• Rest developing fruit on a tile or board to keep it off wet soil.

Pruning. Routine pruning is unnecessary; guide young vines away from paths before they become heavy. In short summers, pinch out growing tips late in the season once several fruits have set, leaving a few leaves beyond the last fruit.

Harvest mature squash in late summer or autumn, before frost, when the rind is hard enough to resist a thumbnail and the stalk is becoming dry and corky; blue-grey colour alone does not prove ripeness. Cut rather than pull, leaving several inches of stalk attached, then cure undamaged fruit in a warm, dry, airy place for about 10-14 days. Store somewhere cool, dry and frost-free, checking regularly for soft spots.

Early spring

Prepare a sunny bed with compost or well-rotted manure and plan space for the vines.

Mid to late spring

Sow individual seeds indoors about 3-4 weeks before your expected planting-out date.

Late spring to early summer

Harden off and plant out after frost, or sow directly into reliably warm soil.

Summer

Water deeply, mulch and feed as fruit develops; keep flowers accessible to pollinating insects.

Late summer

Raise fruit off damp ground and check that developing squash has enough time to ripen before frost.

Autumn

Harvest before frost, cure sound fruit and remove spent vines.

• Grow along the edge of a large vegetable plot, directing vines into an open, mulched area.
• Use in a roomy kitchen garden for bold foliage followed by blue-grey autumn fruit.
• Trail over a sunny bank where the broad leaves can cover bare ground during summer.
• Pair with upright sweetcorn nearby for contrasting height, while giving both crops adequate light, water and nutrients.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Homestead, Farmhouse, Cottage garden and Autumn colour.

Plant it with: Sweetcorn, Nasturtium, Calendula, Borage and Dill.

Wildlife: Flowers provide pollen and nectar for bees, which transfer pollen between male and female flowers. Avoid insecticide sprays while flowers are open.

• Powdery mildew: allow good airflow, keep roots watered and remove badly affected leaves without stripping the plant.
• Slugs and snails: protect young plants with regular evening checks and, where needed, a locally approved slug bait used as directed.
• Squash bugs and squash vine borers in parts of North America: inspect leaf undersides for eggs and stem bases for damage; remove bugs and eggs promptly and use insect mesh before flowering, removing it for pollination.
• Small fruits yellowing and dropping: poor pollination or weather stress is often responsible; maintain even moisture and hand-pollinate a newly opened female flower with pollen from a male flower in the morning.

Normal, non-bitter squash flesh and seeds are not known to be toxic to people, cats, dogs or horses; the plant is not generally regarded as poisonous. Unusually bitter fruit can contain high levels of cucurbitacins and cause serious vomiting and diarrhoea: do not eat it or feed it to animals, and discard the whole fruit because cooking does not make it safe. Prickly stems and leaves can irritate skin.

• Queensland Blue pumpkin (Cucurbita maxima 'Queensland Blue')

  Also has blue-grey skin and orange flesh, but usually has much deeper ribs; Crown Prince is generally smoother and more shallowly ribbed.

• Jarrahdale pumpkin (Cucurbita maxima 'Jarrahdale')

  Usually flatter and more distinctly ribbed, although fruit shape overlaps; a reliable seed or plant label is safer than identifying either cultivar from fruit alone.

Cucurbita is Latin for gourd, and maxima means largest, referring to the large fruits produced by this species.

Propagation. Grow from seed, preferably fresh commercial F1 seed for reliable Crown Prince characteristics. Sow on its edge about 1 in (2.5 cm) deep in warm seed compost, or directly outdoors once the soil is warm; saved seed from this hybrid will not reliably come true.

Accepted botanical name

Cucurbita maxima

In the US and Canada

Introduced in the lower 48 states, Pacific Basin and Puerto Rico.

Native range

Argentina Northeast, Argentina Northwest and Bolivia.

Measured

Average height 500 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.