The Great Pumpkin

Few things evoke the sense of a season as strongly as that first sight of a ripe orange pumpkin in October. Be it thoughts of Halloween or Thanksgiving pie, the spirit of fall is embodied in this familiar member of the squash family. For the young and young-at-heart, one of the best parts of Halloween is the traditional pumpkin carving.

This year, you may want to add a new twist by growing your own pumpkin from seed. Whether grown for carving or cooking, it makes for a great family activity.

Yet, pumpkins can be a handful and growing them may not be for everyone. They ­require lots of room and are notorious for overtaking less vigorous vegetables. Fortunately there are space-conscious cultivars available that are suitable for small gardens or large containers. Of course, if you have dreams of growing a record-breaking giant pumpkin, be prepared to give it the space it requires.

Planting Time
A warm-season crop that thrives in full sun, pumpkins require a late start in the garden, once air and ground temperatures have warmed. Sow seed in late May or early June. It can be done earlier indoors in pots (one to two seeds per nine-centimetre pot), but it is just as easy to sow directly into garden soil or into an outdoor container.

The Perfect Pumpkin
Choosing the right pumpkin is a matter of personal preference. There are many cultivars on the market, offering a wide range of characteristics. Size ranges from enormous to miniature. Colour varies from rich, deep orange to ghostly white, while skin can be deeply ridged or smooth. Different shapes abound, from flattened to elongated to round. Some pumpkins are grown solely for decoration; others for the good eating of their flesh and seeds.

Pumpkin varieties differ in growing habit. There are three main plant types: bush, semi-bush or sprawling/vining. Choose bush or ­semi-bush types if space is a concern. Sprawling types are best suited to larger gardens. Miniature varieties like Baby Boo are suitable for small gardens, with their strong vines trained on a trellis, displaying the developing pumpkins for all to see. Some bush and semi-bush types are suitable for containers, assuming there’s enough soil volume, water and nutrient availability to support a full season’s growth. If you live in the Lower Mainland, coastal regions, Vancouver Island or areas where the growing season is short, choose a cultivar that develops and ripens more quickly. There are two species of pumpkins: Cucurbita pepo and C. maxima, with C. ­pepo cultivars maturing more quickly. Northern gardeners benefit from longer summer days, and Interior growers enjoy warmer summers, allowing them to grow the slower-developing C. maxima cultivars. Time between seeding and harvest can be 90 to 120 days, with the ­pepos averaging 10 to 15 days less to maturity. If seeded at the right time, both types will mature no matter where you live in the province.

Pumpkins are heavy feeders, requiring soil rich in organic matter and nutrients. Soil must be well cultivated, weed free and turned until light and aerated. An addition of peat and organic matter, such as well-rotted compost, is highly recommended. Pumpkins grow best in near-neutral soil pH. Acid soils require lime to raise the pH level, while acidifying fertilizers will help lower pH in basic soils. Pumpkins prefer loamy soil, so if you live in an area where the soil is more clay-based and heavy, work in some sand, peat and organic matter.

Once the soil has been amended, rake it into a small mound or hill to allow for superior drainage, ventilation and sun exposure. Larger-growing cultivars require bigger hills, with a distance of 2.5 to 3.5 metres from the centre of one to the next. Smaller varieties can be planted more tightly. Three to five seeds, sown at a depth of five centimetres, can be planted per hill, thinning to the two healthiest plants after germination. Instead of pulling plants to thin, cut at their base to avoid disturbing the roots of the remaining seedlings. For pumpkins grown in a container (45-litre/10-gallon minimum), one plant per pot is recommended.

Pumpkin plants will grow rapidly if the weather cooperates. They are tolerant of drought, but do best if watered regularly. Blossoms occur within a month of germination and require bee activity for pollination and good fruit set. Plants need little attention unless you are trying to grow a giant pumpkin. If big is your goal, allow only a few fruits to set per plant. By eliminating any new flowers produced, all energy is focused into the selected pumpkins. If quantity is your goal, let nature take its course. Apply water-soluble fertilizer (20-20-20) once a week throughout the summer to improve yield. Only a few pests and diseases will bother pumpkins, particularly plants that get off to a good start and are well tended throughout the summer. Planting disease-­resistant cultivars and practicing crop rotation will further reduce the risk of problems.

Pumpkins will be ready for harvest in the fall. Once the vines begin to get dry and brittle, the pumpkins can be cut from the vine and left to cure in the patch for a week or two (make sure to leave good handles on the would-be jack-o’-lanterns). Protect pumpkins from heavy frost or place into storage until needed. Some white cultivars lose colour if left to grow until the end of the season, so harvest these earlier, when their white colour is at its peak.

Bruce McDonald is chief propagator and an educational instructor at VanDusen Botanical Garden.