Summer squash includes zucchini and cucumber plants. A warmth-loving vegetable, summer squash must be planted after all danger of frost has passed in spring and when soil temperatures are above 60 degrees F. Starting seeds indoors in spring ensures the plants have time to mature in summer. Squash plants do not transplant well, as the roots prefer not to be disturbed. Starting the seeds in peat pots allows you to start them inside, since the peat pots can be planted directly in the garden without disturbing the roots.
Fill individual peat pots with a quality potting mix. Place the pots in a 65 to 75 degree F room or place them on a seedling heat mat set at 70 F to encourage germination.
Sow one to two squash seeds per pot. Sow seeds to a 1-inch depth then water the soil in the pot until it is evenly moist throughout. Place a plastic bag over the top of the pots to preserve soil moisture during germination.
Remove the plastic when seeds germinate, approximately seven to 14 days after sowing. Move the pots to a sunny window in a warm room. Water as needed to maintain moist soil.
Thin each pot to one plant once the plants are 2 inches tall. Pinch off the weaker or smaller plant at the soil level without disturbing the other squash seedling.
Transplant outside once frost danger has passed and once plants are at least three weeks old. Set them outside during the daytime for one week prior to transplanting so they become accustomed to outdoor temperatures and conditions.
Dig planting holes 1 to 2 inches deeper than the peat pot and twice as wide. Set the pot in the hole and refill around it with soil. Cover the rim of the pot so it sits 1 to 2 inches beneath the soil level. Water thoroughly after planting. The peat pot will disintegrate in the garden bed.