University of Vermont Extension 
Department of Plant and Soil Science

Spring (late), Summer News Article


GROWING SQUASH


Dr. Leonard Perry, Extension Professor
University of Vermont
           
Each year the National Garden Bureau picks a vegetable to feature, with the Vegetable of the Year for 2010 being the squash.  There are many varieties of this easy-to-grow native vegetable, in various shapes and colors.
            
Evidence has been found in caves in Mexico and the Southwest that squash existed at least by 5000 B.C., and was being grown by native peoples about 4000 B.C.  Grown together with two other native crops-- corn and beans-- it was one of the "three sisters".  The corn provided support for the beans, and the squash provided a groundcover for weed control.  These crops migrated with humans to eastern North America, where they were discovered and introduced to Europe by early settlers and explorers in the late 16th century.
           
Squash is one of the many members of the cucurbit family, along with other common vegetables such as cucumbers, melons, and gourds.  They are generally divided into two groups, the summer and winter squash, depending on when they are harvested.  You'll see further groupings or types in catalogs, often based on fruit shape.  The summer squash include either crookneck or straightneck, scallop or patty pan, zucchini, and vegetable marrow.  The winter squash include acorn, banana, buttercup, butternut, delicata, delicious, and hubbard. 
           
The summer squash need warm weather for best growth. They are harvested in summer, before the fruits are fully mature in order to have the best flavor and texture.  Seeds should not be fully developed, and the skin should be able to be scraped easily with the fingernail.  They can be harvested at most any immature stage, even quite small.  These store only a few days in the refrigerator but are easily frozen. 
           
To freeze zucchini, yellow crookneck, or other summer squash, wash after harvest and slice.  Blanch in boiling water for 3 minutes to destroy enzymes and bacteria that break down the fruit.  Then cool rapidly in running cold water, or ice water.  Strain and bag, using plastic reclosable freezer bags (sold just for this and heavier than other bags) or a vacuum sealer.
           
Winter squash, on the other hand, are harvested mature in fall around the time of the first frost.   Skins should resist fingernail pressure.  Although this group needs warm weather for seeds to germinate and plants to grow, cool nights are needed for best flavor to develop in fruits.  They store well, such as in a cool room or basement, which stays around 50 to 55 degrees (F).  Acorn squash can store 3 to 4 months, other winter squashes can last up to 6 months with proper storage.  If you are planning to store, make sure to cut the fruit from the vines rather than twist or pull them off.  Breaking the stem off the fruit will leave an opening that rots can enter.
           
All squash need full sun and a well-drained soil.  Squash can get large, so make sure you check the habit and spread before planting.  Many summer squash have been bred to be more compact, so need about 4 square feet per plant.  You can plant several seeds per small raised hill, then thin later to 3 plants per hill.  Space hills about 4 feet apart, with any rows 5 feet apart. 
           
Most winter squash have a semi-bush habit or are vining.  Allow more space for these, about 12 square feet per vining plant.  For those winter squash with small fruits, you can even train them onto a 4-foot high trellis in the back of the garden. 
           
Many sow the large seeds directly into the garden.  Since they need warmth to germinate and grow, wait until the soil warms or else seedlings will grow slowly and seeds may rot.  If the season is cool, or your garden is in the north with a shorter growing season, you may want to start seedlings 2 or 3 weeks early indoors.  Best is to sow into a peat pot or similar which can be planted directly into the garden (they don't like transplanting).  Keep seeds indoors in as much
warmth and sun as possible, and don't allow to dry out.
           
Since squash are vigorous, they require more fertilizer than some other crops.  Work plenty of compost into the soil prior to planting, then fertilize once plants get a few inches tall.  You can use a granular or liquid fertilizer, organic or synthetic.  Fertilize again after a month or 6 weeks. 
           
Mulching will help keep weeds down early on (the plants with their large leaves do this later) that can compete with plants for nutrients, and that foster insects and diseases.  Examples of mulches are straw (not weedy hay), newspapers with some organic material like shredded leaves, or plastic similarly covered.
           
Summer squash will need plenty of water (water deeply and less often is better) through the season, especially during bloom and fruit development.  Winter squash can tolerate some drought once they are established.  Between you and the rain, the soil should be wet to a depth of 10 inches or more each week.  Keeping water off leaves when watering will help prevent powdery mildew disease.
           
Choosing the right site, using mulches with spot hand weeding, and proper culture will go a long way to controlling insects and diseases.  If plants suddenly wilt, often starting one stem at a time, chances are they have a bacterial wilt.  It, and viruses that stunt or deform plants, are spread by insects.  Control these and your plants may remain free of disease.
           
The three main insects to watch for are the striped cucumber beetle, the squash bug, and the squash vine borer.  The adult beetle is yellow to black, striped to spotted, and about 1/4 inch long.  It feeds on most plant parts. Covering plants with fine netting will keep these away.
           
The adult squash bug is flat, brownish-gray, and about 5/8 inch long.    It is usually found on undersides of leaves where it sucks plant juices.  Put some boards in the garden where these insects can hide under, and are then easily found and removed. 
           
The borer does just this, the larvae or caterpillar stage makes tunnels in stems.  This causes them to wilt rapidly, then die.  You can make small cuts in stems to carefully remove borers, cut off badly damaged stems, and early in the season lay foil in the garden to confuse the moths that lay the eggs that hatch the larvae.
           
Whether you grow your own squash, buy it from local farmers, or get it from friends (as often happens with the prolific zucchini), consider putting some up for winter.  You'll benefit from the fresh flavors well past the season, as well as the nutrition of these vegetables.  Zucchini is lower in calories than many fruits and vegetables.  Although winter squash has the same calories roughly as potatoes, it has more than twice the potassium.  Winter and yellow squash  both provide Vitamin A and minerals that may reduce the risk of certain cancers.
           
More details on these and other vegetables of the year can be found on the National Garden Bureau website (www.ngb.org).       
   

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