- Choose a location for your seeds in full sunlight. The garden should get a minimum of 6 hours direct sunlight for best growing results.
- Use a gardening hoe to till approximately 2 inches of compost into the selected area down to a 1-foot depth.
- Mound the tilled soil into a small mass on the topsoil. Press four seeds into the hill to a depth of 1 inch, allowing at least 1 inch of space between each seed. Planting multiple seeds raises your chances of successful germination of at least one seed. Form other hills with a 4-foot space between each one for multiple vines.
- Remove small seedlings from the seed hill by hand if more than one seed germinated. Each hill should only have one seedling; the surrounding soil nutrients will be for that seedling solely so that it can grow as large as possible.
- Water the seedlings once a week. Kabocha pumpkin vines do not like to be waterlogged, so the soil should be well-drained and slightly moist throughout the growing period.
- Sprinkle straw mulch around the growing seedlings to hold moisture in the soil during warm weather spells and provide a safe surface for squash development. Pumpkins that lie in the soil can be subject to rot and pests.