Break up the garden soil with your spade to a depth of 12 to 24 inches.
Mix in 2 inches of aged compost. This boosts your garden's micronutrient levels and also improves soil aeration and moisture retention, all qualities that can enhance your Hubbard squash plants' growth.
Bury the Hubbard squash seeds approximately 1 inch below the soil surface and approximately 5 feet apart. If you're growing more than one row of Hubbard squash, space them apart by 7 to 10 feet.
Irrigate the soil with a water hose or watering can twice a day. Use enough water to moisten the soil to a depth of 2 inches. Keep the flow of water low so that you don't splash away the soil that's covering your Hubbard squash seeds.
Reduce watering once the seeds have germinated. The seeds will typically germinate within seven to 10 days. Once they're sprouted, water once a day and use enough water to moisten the soil to a depth of 6 to 8 inches.
Pile 2 inches of mulch around the Hubbard squash seedlings once they've emerged and reached a height of 3 to 4 inches. The mulch helps keep weeds at bay until the plant is big enough that its shade crowds out any potential weeds.