C. pepo. Start Howden pumpkin seeds indoors in May, to give the plants a head start. Transplant into rich soil in full sun once the soil is warm in June. Howden is popular among home gardeners and growers alike for its uniquely elongated barrel shape that is ideal for Halloween carving. Fruits are quite uniform and measure up at around 35cm (14") tall by 20cm (8") in diameter. Howden's fruits have a large seed cavity with yellow-orange flesh under skins that are bright orange and only slightly ribbed. Excellent potential for Jack-o-Lanterns!
Matures in 100 days (Open-pollinated seeds)
The thick walls of some pumpkins are wonderful for cooking and store well all winter. Pumpkins for carving are thinner walled so kids can decorate them easily. Continue reading below for some key tips on how to grow pumpkins from seed.
Cucurbita maxima & C. pepo.
Easy, but these big plants require lots of room.
Season & Zone
Season: Warm season
Exposure: Full sun
Direct sow or transplant in late spring when soil warms up. For transplants, start seeds indoors 4-6 weeks after the last frost date. Try to get the plants into the ground no later than the summer solstice. Optimal soil temperature for germination: 25-35°C (68-95°F). Seeds should sprout in 7-14 days.
Sow seeds 2cm (1″) deep. Sow 3 seeds in each spot you want a plant to grow and thin to the strongest plant. Space plants at a minimum of 90-120cm (36-48″) apart in rows 120-180cm (48-72″) apart. If starting transplants indoors, consider using the 12-cell plug inserts.
Ideal pH: 6.0-6.8. These big plants need lots of food. Choose a sunny spot with fertile, well-draining soil. Dig in a generous quantity of finished compost and/or composted manure. Dig in 1 cup of complete organic fertilizer under each plant. All pumpkins grow male flowers first, then the female flowers are produced. The female flowers have tiny fruits at the base of the petals and require pollination by bees, mostly. Incomplete pollination is common at the beginning of the season, and results in small fruits that are misshapen at the flower end. Discard these damaged fruits before they rot.
For the largest pumpkins, feed weekly throughout the growing season with fish or kelp based fertilizer. Keep the huge plants well watered, particularly in hot weather. Always water the soil, and avoid any form of overhead watering other than rain. Fruit will grow larger if you keep only one fruit per vine. As the fruit develops, try to gently encourage it to grow at a 90° angle to the vine itself. The largest pumpkin varieties will grow on their sides.
Like other winter squash, pumpkins are mature when they have coloured up well and their stems are crisp. For the best sugar content, cut the stem about 4cm (2″) or so from the body of the fruit. If the weather is dry, allow the pumpkins to cure in the field for 10 days, or in a warm room for 4-5 days. Bring pumpkins in under cover before rain.
In optimal conditions at least 80% of seeds will germinate. Usual seed life: 2 years. Per 100′ row: 60 seeds, per acre: 6.5M seeds.
Diseases & Pests
Powdery Mildew: An airborne fungal disease that causes white spots on the leaves at the end of the season. Several home-sprays are said to be somewhat effective. Spray any of the following at 7-10 day intervals. 1tsp baking soda and 1 quart of water with a squirt of dish soap, or 1 part milk to 9 parts of water. You can add a little kelp based fertilizer to the mix. Resistant varieties get the mildew just a few days later than the other varieties.