Summer Squash

Green, gold, yellow, striped or round zucchini may be the most commonly grown summer squashes, but scalloped pattypan, straightneck, and crookneck are just as easy to include in the summer garden. Some are smooth-skinned others are bumpy; all have soft skin and can be eaten raw and unpeeled. Where space is limited for wandering vines, compact bush varieties, container culture, and trellising are options.

Three Main Shapes

Straightneck types are yellow, more bulbous or slightly swollen at the bottom.
Crookneck types are yellow with a slightly curved neck.
Zucchini may be pale or dark green, striped gray-green, yellow, straight, or round.
Zephyr is a hybrid between summer and winter squashes, similar in appearance to straightneck but tapered at the neck and light green at the bottom.
Patty Pan varieties are saucer-shaded with scalloped edges and may be shades of green, white, or yellow; they have slightly denser flesh.
Check seed packets and catalog descriptions for colors and shapes as well as for disease resistance and low-water requirements.

Planting Squash

Amend soil with compost before planting. Squash is a heavy feeder that benefits from sidedressing with more compost or light applications of fertilizer during the growing season.
Avoid excess nitrogen that causes unwanted leafy growth, lowers fruiting, and attracts insects to lush foliage. An organic phosphorus fertilizer will promote fruiting.
Direct sow May-August or start seeds indoors 4 weeks earlier.
Plant 4-6 seeds in a hill (slight mound) in warm, moist soil. Thin to the strongest 2-3 seedlings after the first 2 sets of true leaves appear. Fruit production of squashes is usually prolific.

Summer Growth

Provide regular, even watering to avoid blossom end rot, an affliction that also can affect tomatoes. Allow soil surface to dry between waterings but maintain moisture to 12 in. deep.
Be prepared to augment calcium content of soil in the future if end rot appears and maintaining soil moisture does not solve the problem.
Wait until morning If leaves look wilted in hot afternoons to see if plants perk up. It is common for large-leaved vegetables to wilt a little in afternoon sun. Check soil moisture before watering.
Watch for powdery mildew on foliage and remove any infected debris. This disease is more prevalent in warm, dry inland areas than near the coast. Some varieties are resistant.
Stay alert for presence of bees if you have blossoms and no fruit. In the absence of a healthy bee population, hand pollination may be needed. Use a cotton swab to carefully transfer pollen from a newly opened male flower to female flowers. (Male flowers have narrow stems, form earlier, and appear lower on vines; female flowers are swollen at the base).
Watch for cucumber beetles and squash bugs or prevent them by using row covers when plants are very young; check regularly to be sure that none are trapped underneath netting. Handpick bugs and destroy any eggs on the undersides of leaves.
Remove row covers when flower formation begins so that bees can begin pollination.
Harvest zucchini, straightneck, zephyr, and crookneck varieties when they reach 4-7 in. long, pattypan at 3-4 in.; or any variety when smaller to use as miniature vegetables.

Additional Information

Sonoma County Master Gardener Vegetable Planting Summary
https://sonomamg.ucanr.edu/Food_Gardening_with_Less_Water/
http://ipm.ucanr.edu/home-and-landscape/squash/index.html
http://ipm.ucanr.edu/home-and-landscape/squash/cultural-tips/

February 2022