Squash, Summer

What to Plant:  Seeds; transplants are often available but must be handled carefully
Dates:  See Vegetable Planting Calendars
Season:  Warm
Group:  10
Rotation:  Fruit
Edible:  Fruit, blossoms
Nutrition:  Vit C, Vit B6, Vit K, Riboflavin, Folate, Potassium
Seeds/oz:  155 – 375
Seed Viability:  4 – 6 years
Soil temp:  70º F – 95º F (85º F)
Planting Depth:  1/2″ – 1″
Germination:  5 – 10 days
Spacing:  3′ – 5′
SqFt Spacing:  1 per 2 Sq Ft if trellised, 1 per 9 or 16 Sq Ft on ground
Days to Harvest:  50 – 65
Length of Harvest:  16 weeks 
Origin:  Mexico and Central America

Bed prep:  Prepare beds by adding compost at 1/3 of volume and SROF at ½ cup per square foot.  Mix well by spading.

Planting:  Large seed benefits from pre-soaking for 1 – 2 hours before planting.  Plant 4 – 6 seeds in a 6″ – 8″ circle in each space.  Thin to the strongest 3 plants when they have 3 – 4 leaves.  Many gardeners plant 3 or 4 onion seedlings in the middle of the squash seed to deter the squash vine borer.

Watering: Once a week without sufficient rainfall.

Aftercare: Keep bed free of weeds – mulch.  Watch for disease or pests.  Drought conditions cause misshaped fruits, keep evenly moist.  Side dress with 1/4 cup SROF when the vine starts to bloom, and again every month until the vine begins to die back.   Water at the soil level to avoid mildew issues.  Drip irrigation is recommended.

Harvest:  Harvest with shears or a sharp knife.  Do not pull the fruit from the vines.  The less the vines are disturbed, the fewer problems they have.  Harvest the fruits while they are young.  The skin should be somewhat shiny and you should be able to pierce the skin with your thumbnail. Yellow squash is best when it is 4″ – 6″ long.  Zucchini is best between 6″ and 8″.  Scalloped or patty pan types are best when they are no larger than the diameter of a baseball.  “Baby” scallops are delicious.  Harvest summer squash every other day to make sure you are picking at peak flavor and to keep the plants productive.  Remove any damaged fruits immediately – if they are left on the vine the vine will begin concentrating on ripening seed and production will cease.

Squash Pests:  The main pest you will need to be vigilant for is the squash vine borer.  There are several strategies for control.  One is to keep a lightweight floating row cover over the vines from planting until flowering.  Remove when flowers begin to develop to allow pollination or hand-pollinate daily under the cover.  Bt or Neem can be sprayed on the base of the vine, but this must be done every 2 – 3 days to control the borer.  You can also apply Surround WP to the base of the stem.  This kaolin clay product deters the adult moth from laying eggs in the stem.  Surround WP must be reapplied after rain. 

Additional Information: Summer squashes include Yellow Crookneck, Yellow Straightneck, Zucchini, and scalloped varieties. 

History:  Squashes have been in cultivation for thousands of years.  Archaeologists have found squash seeds stored away in caves in Mexico that date to 10,00 years ago.  Portuguese and Spanish explorers in the Americas introduced squashes to Europe and other ports of call.  Thomas Jefferson grew several types of summer squash, including scalloped varieties which he called “cimnel”.  William Clark recorded the squash cultivation of the Arikara tribe in his journals in 1804 on the Lewis & Clark Expedition.  George Washington was also an avid squash grower.