Kabocha Squash

Kabocha squash, also known as Japanese pumpkin, is a versatile and nutritious winter squash variety that boasts a sweet, nutty flavour and velvety texture. Ideal for soups, stews, and roasting, it is a delicious and hearty addition to any meal. In this comprehensive guide, we will cover planting, growing, harvesting, and storing Kabocha squash, ensuring a bountiful harvest for all garden enthusiasts.

Days to Grow90-100 days
Square Foot Garden Spacing1 plant per 9 square feet (3×3)
Gardening EffortModerate
When to Plant3-4 weeks before the last expected frost date
Yield2-4 fruits per plant
Frost ToleranceNot frost tolerant
Hours of Light NeededAt least 6-8 hours of full sun
Soil ConditionspH 6.0-6.8, well-draining, rich in organic matter
Days to Maturity90-100 days

Gardening Shortcut Links

Square Foot Gardening Section

Selecting the Perfect Kabocha Squash Seeds

To begin your Kabocha squash journey, choosing high-quality seeds from a reputable supplier is essential. Opt for disease-resistant varieties, such as ‘Sunshine,’ ‘Sweet Mama,’ or ‘Emperor,’ which have been specifically bred for superior performance and resistance to common squash ailments.

Planting Kabocha Squash: Timing and Soil Preparation

Kabocha squash is a warm-season crop, requiring temperatures between 65°F and 95°F for optimal growth. To ensure successful germination, plant seeds directly in the garden or start them indoors approximately 3-4 weeks before the last expected frost date.

To prepare the soil for planting, follow these steps:

  1. Choose a sunny location with well-draining soil, as Kabocha squash thrives in full sun and requires adequate drainage to prevent root rot.
  2. Amend the soil with organic matter, such as compost or well-aged manure, to improve fertility and soil structure.
  3. Test the soil pH, aiming for a range between 6.0 and 6.8 for optimal nutrient availability.

Planting Kabocha Squash Seeds and Seedlings

To plant Kabocha squash seeds or seedlings, follow these guidelines:

  1. Space seeds or seedlings approximately 3 feet apart in rows, with rows, spaced 4-5 feet apart. This allows ample room for the sprawling vines to grow.
  2. Plant seeds 1 inch deep, and water thoroughly after planting. Keep the soil consistently moist but not waterlogged, as this can cause seeds to rot.
  3. Transplant seedlings outdoors once they have developed at least two true leaves, and all risk of frost has passed.

Caring for Your Growing Kabocha Squash Plants

To ensure a healthy and bountiful harvest, follow these essential Kabocha squash care tips:

  1. Water regularly, providing 1-1.5 inches of water per week, depending on rainfall and soil type. Use drip irrigation or soaker hoses to minimize leaf wetness and reduce the risk of disease.
  2. Apply a balanced fertilizer when vines begin to develop, and fruits start to form. This supports strong growth and enhances fruit quality.
  3. Control weeds using mulch or hand-pulling, as weeds can compete with squash plants for water and nutrients.
  4. Monitor for pests and diseases such as squash bugs, cucumber beetles, and powdery mildew. Employ integrated pest management techniques, including crop rotation, biological controls, and organic or synthetic pesticides when necessary.

Harvesting Kabocha Squash: When and How

To determine when your Kabocha squash is ready for harvest, look for the following signs:

  1. Ripe Kabocha squash will have a deep, rich colour with a dull, matte finish on the rind.
  2. The stem should be hard and corky, and the skin should be difficult to pierce with a fingernail.
  3. Timing typically ranges from 90 to 100 days after planting, depending on the specific variety and growing conditions.

Follow these steps to harvest Kabocha squash:

  1. Use a sharp, clean pair of pruning shears to cut the squash from the vine, leaving a 2-inch stem attached to the fruit. This helps to prevent premature rot and prolongs storage life.
  2. Avoid lifting or carrying the squash by its stem, as this can cause it to break off and create an entry point for bacteria and fungi.
  3. Gently brush off any dirt or debris from the squash before bringing it indoors.

Curing Kabocha Squash for Improved Storage

Curing Kabocha squash allows the skin to harden and the natural sugars to concentrate, enhancing flavour and storage life. To cure your squash, follow these steps:

  1. Place the harvested squash in a warm, dry, and well-ventilated area with temperatures between 75°F and 85°F for approximately 10 to 14 days. This helps to harden the skin and heal any minor cuts or abrasions.
  2. Rotate the squash periodically to ensure even curing and to prevent any soft spots from developing.

Storing Kabocha Squash for Long-Term Enjoyment

Once your Kabocha squash is cured, it’s time to store it for future use. To maximize storage life, adhere to these guidelines:

  1. Choose a cool, dark, and well-ventilated area for storage, such as a basement or root cellar. Ideal storage temperatures range between 50°F and 60°F, with relative humidity around 60% to 70%.
  2. Place the squash on a shelf or rack for proper air circulation. Avoid stacking the squash, as this can lead to bruising and promote decay.
  3. Inspect the squash regularly for any signs of spoilage, such as soft spots, mold, or an off smell. Remove and discard any affected squash to prevent the spread of decay.

By following these comprehensive guidelines for planting, growing, harvesting, and storing Kabocha squash, you’ll be well-equipped to enjoy a bountiful and delicious harvest. Whether you’re a seasoned gardener or new to the world of squash cultivation, Kabocha squash is a rewarding and versatile addition to your garden, offering a delectable and nutritious treat throughout the cooler months.

Seeds and planting
Links and Resources

Recommended Products
(These are some of what I use)

These nursery bags
These Grow bags


mybackyard.ca Seeds Page
Get a Head Start on Spring: The Benefits of Starting Your Seeds Indoors
Saving Vegetable Seeds: A Comprehensive Guide to Gardening Success
myBackyard.ca Planting Guide
Pollock Tomatoes (North hardy Tomato variety)
Tomatoes (Useful information on starting tomatoes from seed)

DIY Garden Irrigation System: A Detailed Guide for Northwest Ontario

Blog Posts

When to start planting seeds
Germination testing your seeds
Looking for sources for seeds?
Heirloom seeds
Chitting your way to more potatoes
So it's before the first frost; what can I plant?


Individual seed and plant information is available in the  "Gardening Shortcut Links" above under "North Hardy Plants to grow". I have successfully grown all of these, and most I grow year to year.






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