Ancient Maya Treasure, The Blue Giant of the Highlands

Guatemalan Blue Squash, also known as Guatemalan Blue Banana Squash, is one of the most breathtaking winter squash varieties you can grow: a true giant that produces enormous, elongated fruits (15-30+ pounds) with striking slate-blue skin and thick, honey-sweet orange flesh. This vigorous variety sends out wandering vines (10-15+ feet) that produce harvests measured in pounds, not numbers. Each massive fruit stores for 3-6 months or longer, turning a single harvest into months of nourishment for your family.

Its complete history can be found on our blog.

Why Grow Guatemalan Blue?

• Enormous size: Single fruits weigh 15-30+ pounds; one squash feeds a family for weeks
• Striking appearance: Distinctive slate-blue grey skin, unlike any other squash
• Exceptional sweetness: Thick orange flesh as sweet as honey, rivalling the best winter squash
• Outstanding storage: Properly cured fruits store 3-6 months or longer
• Vigorous production: Productive vines produce multiple massive fruits per plant
• Cold-hardy: Thrives in Canadian summers with long daylight hours
• Ancient heritage: Direct connection to Maya agricultural wisdom spanning millennia
• Growing Instructions

Days to Maturity: 100-110 days from seed to harvest

Planting Season: Start seeds indoors 3-4 weeks before the last frost for the earliest harvest in short-season areas, or direct seed after all danger of frost has passed and the soil has warmed to at least 15.5°C. Guatemalan Blue is a heat-loving plant that thrives in warm soil and weather.

Sowing: Plant seeds 1 inch deep, 2-3 seeds per planting spot. Thin to the strongest seedling when plants are 3-4 inches tall. Space plants 4-6 feet apart, as these are vigorous vines that need substantial room to sprawl (10-15+ feet of growth). It can be grown on very sturdy trellises, but fruits will need strong support slings due to their enormous size.

Sun & Soil: Full sun. 8+ hours of direct sunlight daily. Rich, well-drained soil heavily amended with compost. Guatemalan Blue is a heavy feeder that demands fertile soil and consistent moisture to produce those enormous fruits.

Water & Care: Water deeply and consistently throughout the growing season, especially during flowering and fruit development. Mulch around plants to retain moisture and suppress weeds. Side-dress with compost or balanced fertilizer mid-season to support continued growth.

Harvest: Harvest when the fruit is fully mature. The skin should be hard slate-blue grey, and you shouldn’t be able to pierce it with your fingernail. The stem will begin to dry and turn brown. This typically occurs in late September through October in most Canadian regions. Harvest before a hard frost. Even a light frost can damage fruits and reduce storage life. Cut fruits from vines with several inches of stem attached (the stem is your handle for months of storage).

Curing: Cure in a warm, dry place (21-27°C) for 2 weeks to harden skin and improve storage quality. This step is essential for maximum storage life.

Storage: Store in a cool (10-15°FC, dry place with good air circulation. Properly cured fruits will store for 3-6 months or even longer. You can have squash well into winter and sometimes into spring, providing fresh vegetables when the garden is buried in snow.

Canadian Climate Notes

Guatemalan Blue thrives in Canadian summers despite its requirement for a long, warm growing season. The extended daylight hours of northern latitudes compensate for cooler temperatures, producing vigorous, productive plants. The cool nights of late summer and early fall actually improve flavour and storage quality.

Southern Canada (Zones 5-6): Direct seed in late May after soil warms, or start indoors in early May for the earliest harvest.

Northern regions (Zones 2-4): Start indoors in early May and transplant in early June, when the soil is warm and frost danger has passed. Choose the warmest, most protected garden locations.

Plants grow vigorously through July and August. Fruits mature in late September through October. Harvest before the first hard frost.

Culinary Notes

The thick orange flesh is lovely—honey-like, rich, and intensely flavoured. The texture is smooth and dense, perfect for:

• Roasting: Cut into chunks, toss with olive oil and herbs, and roast until caramelized
• Soups: Makes vibrant, velvety squash soup
• Mashing: Steam or bake, then mash like sweet potatoes
• Baking: Add to breads, muffins, pies, and desserts
• Stews and curries: Adds sweetness and body to savoury dishes

The seeds are also delicious: clean, toss with oil and salt, roast at 350°F for 10-15 minutes for a nutty, crunchy snack.

Hardiness Zones

3-10 (grown as warm-season annual; frost-sensitive)

Seed Saving

Guatemalan Blue is insect-pollinated (primarily by bees) and will cross with other varieties of Cucurbita moschata—including butternut squash, cheese pumpkins, and other moschata varieties. For true seed, isolate by ½ mile from other C. moschata varieties, or hand-pollinate and bag flowers.

To save seed, allow the fruits to mature on the vine fully. They’re already mature when you harvest them for eating, so any fruit you harvest is suitable for seed saving.

Cut open the fruit, scoop out the seeds and pulp, place them in a bowl with water, and let them ferment for 2-3 days. This fermentation process removes the gel coating and improves germination. After fermentation, rinse seeds thoroughly, removing all pulp. Spread on screens or plates to dry completely (1-2 weeks in a warm, dry location). Store in a cool, dry place.

Seeds remain viable for 4-6 years.