How to Grow Pumpkins Canada | Regional Planting Calendar

Soil pH range

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Botrytis cinerea

Soft brown fruit decay; Fuzzy grey-brown mould

RHS pumpkin guide names grey mould among pumpkin diseases.

RHS pumpkin guide names powdery mildew among pumpkin diseases.

Cucumber mosaic virus (CMV)

Covered by the RHS phrase "Cucumbers and other cucurbits"; pumpkin is Cucurbita maxima.

Small yellow areas on the upper leaf surface expanding and browning, with grey mould on the underside directly beneath. Favoured by moist conditions. Resistant varieties work; fungicides only work preventatively.

Erwinia tracheiphila

Vines wilt severely then die fast. There is no chemical control once a plant is infected, and the bacterium overwinters inside the cucumber beetles rather than in your soil -- so this is a pest problem presenting as a…

Cercospora beticola

Dark spots with lighter centres and darker margins; centres may drop out and lesions merge into blight. Progresses fastest at 79-90F, where new leaves can be infected every 7 to 10 days. Overwinters in crop debris and…

Alternaria dauci

Small circular tan spots enlarging past 1.5 inches with concentric rings and a bull's-eye appearance, followed by severe leaf drop. Driven by bright sunshine with frequent dew or rain at 60-90F. Overwinters on plant…

Colletotrichum spp.

Sunken reddish-brown lesions with yellow halo (anthracnose)

Leaf spots beginning yellowish or water-soaked, turning brown to black with a shot-hole look; black, circular, sunken cankers on the fruit. Needs rainy, cool weather for several days. The fungus overwinters on old…

Didymella bryoniae

Brown or tan leaf spots, and stem cankers weeping a brown gummy substance, with vines wilting mid-season. No resistant varieties exist, and it survives on debris year to year -- so clearing debris and rotating to a…

Gastropoda (slugs, various spp.)

RHS pumpkin guide lists slugs and snails among pumpkin pests.

Gastropoda (snails, various spp.)

RHS pumpkin guide lists slugs and snails among pumpkin pests.

Trialeurodes vaporariorum

Tiny white sap-feeders in groups on leaf undersides; the honeydew grows sooty mould that cuts photosynthesis and yield, and they vector numerous viruses. Reflective mulches are effective, and beneficial insects do much…

Tetranychus urticae

Pale yellow and reddish-brown stippling on the upper leaf surfaces, developing very fast and able to kill or badly stunt plants. Hard to spot until there are hundreds per leaf. Severe outbreaks are linked to…

Aphis gossypii

Found chiefly on leaf undersides, sucking sap and reducing both quality and quantity of fruit; infested leaves curl downward and may brown and die. Usually arrives once vines start to run. Transmits cucumber mosaic…

Acalymma vittatum

A yellow beetle about a fifth of an inch long with three black stripes. It feeds on every part of the plant from emergence, but the real damage is that it transmits bacterial wilt -- which overwinters inside the…

Diabrotica undecimpunctata howardi

Begins feeding as soon as plants emerge and either kills them outright or badly slows growth; the larvae bore into roots and stems. Fabric row covers, handpicking and weed control; remove covers during flowering.

Melittia cucurbitae

Larvae tunnel into the stems, often killing the plant when they feed in the basal part of the vine. The signs are a vine wilting suddenly and sawdust-like frass coming from holes in the stem. It overwinters in the soil…

Diaphania nitidalis

Caterpillars tunnel into flowers, buds, stems and fruit, with sawdust-like frass protruding from small holes; damaged fruit often cannot be identified until it is cut open. It cannot survive winter in the Carolinas --…

Anasa tristis

A sap feeder that frequently kills squash plants outright; leaves wilt rapidly and go brittle. Adults overwinter unmated in sheltered places and appear slowly in spring, laying brick-red egg clusters as the vines begin…

Zea mays

Part of the "Three Sisters" polyculture: the sprawling pumpkin foliage shades the soil, suppressing weeds and conserving moisture beneath the taller sweetcorn.

Pumpkins throw a flush of male flowers first, on plain slender stalks, before the females appear with a miniature fruit already formed behind the petals. A fortnight of flowers and no pumpkins is the normal sequence, not a fault.

Once pollination takes, the fruit swells fast in the shade of its own leaves. Leave the foliage alone — those leaves are what fills the pumpkin, and stripping them to "let the sun in" costs you size.

A single trailing plant will cover several square metres. Let the vines run over ground you are not using, or train them along a path edge. Where space is short, choose a bush variety rather than fighting a trailing one.

Ripeness shows in the stem, not the colour. A pumpkin is ready when the stem has gone hard and corky and the skin resists a thumbnail. Colour arrives well before the fruit is actually cured enough to store.

A pumpkin sitting on cold wet ground rots on its underside before it ever reaches the kitchen. Slide a tile, board or upturned crate underneath once the fruit starts to size up — it costs nothing and saves the crop.

Left to one fruit per plant and fed generously, pumpkins reach a size that surprises people. If you want a large one, remove competing fruit early and let the plant put everything into a single pumpkin.

As the crop finishes, the leaves collapse and the fruit is left sitting exposed. That is the signal to start checking stems for ripeness — and to get the crop in before the first hard frost, which ruins keeping quality.

Ripe fruit across a whole bed at once is normal: pumpkins set within a narrow window and finish together. Plan for the glut — a cured pumpkin keeps for months, an uncured one does not.

Cut each pumpkin with several inches of stem still attached, and carry it by the fruit rather than the stem. A stem that snaps off leaves an open wound, and that fruit will rot rather than store.

Fungal rot on a stored pumpkin starts wherever the skin was bruised, cut or left damp. Cure the fruit in warmth for around ten days first, store somewhere cool, dry and airy, and check them over regularly — one rotting fruit will take its neighbours with it.