SUMMER SQUASH TIDBITS

  • If you’re growing zucchini, it’s pretty much the same as growing summer squash. They’re called “summer” squash because they’re harvested “immature,” and don’t store through the winter like “winter” squash.
  • Growing summer squash requires lots of bees. Some of our friends don’t have many bees in their garden so got only a few zucchini last year. We’ll show you how to circumvent this problem if you have it.
  • The most popular summer squash for growing is Zucchini followed by Yellow Summer Squash. Other summer squash varieties you can grow are cousa squash, yellow crookneck squash, and pattypan squash.
  • The name “zucchini” is the Italian word for vegetable plant (yeah, creative, huh!?).
  • The French word for zucchini is “courgette” which means “we are going to grow a long, skinny, greenish vegetable that kids hate.” (I may be stretching the meaning a bit :)). The UK, Ireland, S. Africa, France, Greece, and New Zealand use “courgette” rather than “zucchini.”
  • Zucchini (and summer squash) came from the America’s, but was popularized by the Italians; hence the name zucchini.

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WHEN TO PLANT

  • Growing summer squash is relatively easy compared to many fruits and veggies.
  • Summer squash needs only about 40 to 60 days to begin producing fruit.
  • We usually plant our zucchini and yellow summer squash just after the last frost (we hope). That’s usually around mid-May in NE Washington State.
  • In a more southern climate you can plant around the first of March or mid-March.
  • If you want to you can successively plant summer squash every couple weeks for the first months of spring. We’ve not needed to do that as we get lots of squash from our dozen or so plants all summer.
  • If you do plant later plantings, time your last planting to about 70 days before the first average frost date in the autumn.
  • Summer squash can be planted indoors a few weeks before the last frost if you use peat pots or soil blocks.

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WHERE TO PLANT

  • Zucchini and other summer squash require lots of sunlight to produce lots of fruit.
  • A minimum of 6 hours in warmer climates and more in cooler climates is ideal.
  • Organic summer squash prefers well-drained soil that’s loaded with compost and/or composted manure.
  • Summer squash likes warmth and won’t produce well in cold weather. Last year was a very cool summer and our plants didn’t produce as well as we’d have preferred, but we still had a decent crop.

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PREPARING THE SOIL

  • Summer squash prefers a slightly acidic soil, about 6.0 to 6.5 pH level, although you can get by with alkalinity up to around 8.0.
  • Like most vegetables, summer squash needs a good supply of Nitrogen, Phosphate, and Potash (N-P-K). We’ve found that a good supply of compost and well-composted manure provides most of the needed nutrients for your squash.
  • Bloodmeal is also a great source of Nitrogen, and Bonemeal is a good source of phosphorus.
  • Wood Ash, especially from hardwood fires, is a good source of potassium.
  • In the days of yore, gardeners would dump a bushel (about 40lbs.) of composted manure in a hole below where each summer squash was to be planted. It can still be done, but it’s more work with less availability of manure than many years ago.
  • Compost and composted manure also generally provide for the supply of trace elements to your garden as well; Calcium, Magnesium, Zinc, Sulfur, Boron, Cobalt, Copper, Iron, Iodine, Tin, and Molybdenum.
  • If you are uncertain what your soil is lacking, purchase an inexpensive pH tester as well as a N-P-K soil tester.
  • It’s a good practice when preparing your soil for growing summer squash to rototill as much crop residue into the soil as possible in the fall or early spring in order to allow it to fully decompose before planting your summer squash.

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CHOOSING THE RIGHT SEED VARIETIES FOR YOUR AREA

  • Zucchini and other summer squash will grow in most areas, so you should be able to plant this rewarding crop in almost any area, hot or cool.
  • Summer squash may be susceptible to powdery mildew, and although resistant seeds have been developed, we’ve never had much problem with these diseases.
  • Don’t water late in the day; water in the early morning so the plants will dry out by mid-day and the various fungal diseases won’t have a chance to germinate.

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SEEDS AND GERMINATION

  • Summer squash will germinate in soil temps between 60° and 105°F. They won’t germinate in cooler soil though.
  • The best germination temperature is around 85° to 95°F. At this temperature you should see the seedlings in 5 or 6 days.
  • The soil should be moist but not saturated through the germination phase.
  • For faster germination, you may use black plastic mulch to heat the soil more quickly in the spring.

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STARTING SUMMER SQUASH INDOORS

  • If you decide to start your seeds indoors, use one part each of a sterilized potting mix, perlite, sphagnum moss, and compost.
  • Don’t use garden soil as it may have bacteria that will grow too quickly in your home or greenhouse and kill your plants.
  • If you plant summer squash in pots, we recommend peat pots. Soil blocks are even better as you don’t even have to cut the bottoms out like you do with peat pots.
  • Start your seeds about 3 or 4 weeks before transplanting to your garden.
  • Plant 2 seeds per peat pot or soil block at a depth of about 1 inch.
  • Once your seedlings emerge, choose the strongest seedling and clip the weaker one off with a scissor.

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TRANSPLANTING SUMMER SQUASH TO YOUR GARDEN

  • If you’re transplanting to your garden, you can use black plastic mulch and row covers to aid you in planting a couple weeks before the last frost.
  • About a week before you plan to transplant your summer squash to your garden, begin to reduce your plant’s water and move your plants outdoors during the daytime. This is called hardening off.
  • After a week or so you can plant your zucchini or other summer squash to your garden.
  • Your plants should have at least 4 true leaves when you plant them.
  • If possible, plant them on a cloudy day or early in the morning; water well after planting.
  • Using a garden trowel, dig a small hole large enough to put the peat pot or soil block into; lightly pack soil around the pot, leaving your plant’s collar even with the soil.
  • Space your plants 2 to 3 feet apart and if you have more than one row, space the rows 4 to 5 feet apart.

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PLANTING SEEDS DIRECTLY TO YOUR GARDEN

  • You can plant a week or so before the last frost if you warm the soil with black plastic and keep the plants from freezing with row covers.
  • While some gardeners like to get a head start planting summer squash indoors, seeding directly to your garden is considered the best practice.
  • Using a soil thermometer, check your soil; once it’s around 70°F you can plant 2 or 3 seeds at about a 1 to 2 inches deep, 24 to 36 inches apart in rows 4 or 5 feet separated.
  • Once your plants are well-established, thin them down to just one seed per hill, choosing the most vigorous plant.

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SUCCESSFULLY GROWING SUMMER SQUASH

  • As mentioned previously, black plastic mulch and row covers are effective for giving your growing summer squash an early boost in the spring.
  • Plastic mulch can also keep the weeds down and keep moisture in the soil.
  • If your plants begin to wilt, water them. If you don’t have lots of bees in your area, you may need to hand pollinate your squashes.
  • You can hand pollinate by using a small brush, like a paint brush, and brushing it first across the male flowers and then across the female flowers to pollinate your squash.
  • If you have enough land and accessibility, you could put an ad on Craigslist inviting bee farmers to place some hives on your property. This will ensure all your crops are well-pollinated.
  • Another way to attract bees is to plant flowers like foxgloves, sunflowers, or Echinacea near your garden.
  • Pruning your zucchini or other summer squash once the main stem has reached about 36″ in length will help your plant to concentrate on producing flowers and fruit rather than leaves.
  • You can also bury the main vine in dirt later in the season to encourage secondary rooting which provides a boost to your plants.
  • Jenny’s Tip – When you’re growing summer squash, spray your plants every couple of weeks with a liquid organic leaf spray fertilizer. We highly recommend Organic Garden Miracle™. It naturally stimulates your garden plants to produce more plant sugar in the photosynthesis process. That in turn creates a more robust plant, more produce from your garden, and better and sweeter flavor. And they have a really good warranty!
  • If you’ve fertilized with compost and/or composted manure early in the season, there should be no need of fertilization during the growing season with the exception of the aforementioned leaf spray.
  • After the seedlings have emerged, position the row covers over the plants, securing the edges with soil or staples.

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MULCHING & WEEDING

  • Black plastic is a great way to mulch at the beginning of the season as it heats the soil, retains soil moisture, and controls weeds.
  • Once the soil temps have reached about 75°F, organic mulches such as 2 to 4 inches of grass clippings or straw add nutrients to the soil, suppress weeds, and contain moisture in the soil.
  • Don’t pile mulch on the growing squash plants themselves or the will suppress these plants also.
  • As summer squash roots tend to be quite shallow, any close weeding should be done by hand.
  • The plants will naturally suppress most weeds once they mature.

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WATERING SUMMER SQUASH

  • Depending on mulching, how hot the weather is, and your soil type, most summer squash requires one good weekly watering of about an inch of water, and sometimes two inches.
  • Sandier soils need watered more frequently with less water as the water will drain out of the soil more quickly.
  • Sandy soils should be watered more frequently but with lower amounts applied at any one time.
  • As your squashes ripen, make sure you water less to avoid rotting the fruit.
  • Reduce watering amounts as the fruits ripen to avoid fruit rots; however, be careful not to under-water as well as the fruit requires sufficient moisture to mature properly as well.
  • Avoid afternoon or evening watering unless you are using drip irrigation. Late watering will not allow the moisture to evaporate from your squash plants and may encourage mildew or other moisture-related ailments.

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COMPANION PLANTING AND ROTATION CONSIDERATIONS

  • A good companion for squash plants is borage, which is reputed to repel the tomato hornworm and improves flavor and growth; it also attracts bees.
  • Marigolds and nasturtiums, as with many plants, are good at repelling beetles and squash bugs; these also attract bees.
  • Legumes such as peas and beans are beneficial to summer squash because of their nitrogen-fixing attributes.
  • Radishes repel cucumber beetles; plant them with cucumbers and squash (they’re in the same family).
  • Potatoes reputedly inhibit the growth of squash, although I have to say I didn’t really notice this last year when they were next to each other.
  • Avoid following members of the cucumber or melon family for at least 2 to 3 years to make sure your garden has time to rid itself of root nematode pathogens.

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WHEN TO HARVEST

  • Zucchini and other summer squash ripen quickly in hot weather and have a tendency to become, as we call them, “footballs.” This just means they’ve gotten too big to eat.
  • Pick summer squash when they are less than 2 inches in diameter and about 6 to 10 inches in length.
  • Oversize squash can be composted. It’s best not to allow squash to get too large as they’ll sap the strength from your plants until picked, causing the younger fruit not too develop.
  • Check your plants every day or two during the warmer part of the season as they’ll produce prolifically during this time.
  • It’s best to use a sharp paring knife or pocket knife to cut the squashes from the plants, but I often forget to bring a knife, so a sharp twisting motion will also remove the squash, although it’s not ideal.
  • Some people deep fry the flowers in batter or eat them in salads. I’ve not tried this, but maybe someday I will.

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STORING SUMMER SQUASH

  • Summer squash not only don’t store into the winter, they really don’t store well in the summer either.
  • Place loosely in your vegetable drawer of your fridge for 3 to 5 days (in our experience). If you don’t eat them, compost them or make them into a relish.
  • Your refrigerator should be about 45°F average temp.
  • Summer squashes such as zucchini and yellow squash should be stored in a plastic bag in the refrigerator for up to five days.
  • It is not recommended to can zucchini or other summer squash, but we’ve sliced zucchini and yellow summer squash and blanched it for a minute or so in boiling water, place it in zip lock-type bags, and frozen it for soups and casseroles in the winter – with very good success.

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PREVENTATIVE AND NATURAL SOLUTIONS TO COMMON PESTS

  • My least favorite subject is pests; they can damage or even wipe out your crops. Fortunately, there are some effective organic solutions to controlling many pests.
  • The worst squash pest is the cucumber beetle, which comes in your choice of striped or spotted varieties (OK, you don’t have much choice).
  • These nasty little buggers will eat both the leaves and fruit of any squash family member, which includes summer and winter squashes, cucumbers, and melons.
  • They also spread bacterial wilt just in case eating your plants isn’t quite enough.
  • Row covers are the best organic defense against these rapacious beetles (I don’t know what that means, but it sounds pretty wicked!).
  • We’re opposed to the use of chemical pesticides for many reasons, some of which are that these pests begin to become resistant to pesticides and also pesticides eliminate both good and bad bugs.
  • Infestations can be dealt with using an organic permethrin (comes in both organic and inorganic), but again, if you don’t have to resort to any insecticides your garden will be better off.
  • Another voracious pest is the squash bug. Early in the season, this bug eats mostly leaves and can be devastating to seedlings if not contained.
  • Unlike cucumber beetles which decline in harmful activity through the gardening season, squash bugs get more numerous and damaging as the summer progresses and begin to eat the fruit as it ripens.
  • Squash bugs are brown to black and over a half inch long on the average.
  • If crushed, squash bug has a very yucky odor. When I was a kid we called them “stink bugs” although there may be another bug that actually bears that name more legitimately.
  • In the spring, adult squash bugs lay neat clusters of eggs on the underside of leaves. The nymphs stay under the leaves during this time period which can last for several weeks.
  • Healthy plants seem to be a good defense against these pests.
  • Row covers early in the season help control these pests as well.
  • If your garden isn’t overwhelming in size, you can inspect the undersides of your leaves and crush any eggs you find and hand pick adults and nymphs and drop them into a bucket of soapy water to drown them.
  • One way to trap bugs is to lay out boards or newspaper in your garden. Pick up the boards or newspapers in the morning; these bugs will congregate under these items and are much easier to catch than when they’re on your plants.
  • Rototill under all cucumber family plants in the fall to reduce areas near your garden where they can overwinter.
  • Another nasty pest is the squash vine borers. They typically appear about the time the vines begin to spread out across your garden.
  • Squash vine borers are an inch long or so, quite fat, and are white with a brown head.
  • They are the larvae of a small moth with dark front wings and light rear wings and a red abdomen. The moths lay eggs in the late spring or early summer near the base of your squash vines.
  • The borers appear about a week later and drill a hole in your vine to get inside them. You’ll see a small hole and green excretions below the hole. And you’ll see the vine die rather suddenly.
  • To prevent squash vine borers from decimating your crops, first, watch for the moths (and listen…they have a buzz when they fly that’s unusual for moths).
  • You can also use yellow-colored bowls filled with water to trap these moths; they’re attracted to the color, and will fly into the bowls and drown.
  • At this point, it’s a good idea to use row covers for about 2 weeks until the moths disappear again. Make sure you cover the edges of the row covers with dirt to seal out the moths.
  • If your plants begin flowering during this time, you can hand pollinate your squash if necessary. Don’t use insecticides as they can also kill beneficial insects that pollinate your crops.
  • If you discover the borer has created a hole before the plant wilts and dies, you can sometimes carefully cut a hole in the vine and remove the borer. Cover the vine and the hole with dirt as it will many times send roots into the soil from the cut area.
  • If you find a vine that’s been killed by a borer, cut back the vine and destroy it.
  • Aphids are also common pests that can be found on the undersides of your squash leaves. You’ll know they’re there if you see leaves turning yellow and crinkling or curling.
  • Aphids suck the juice from your plant leaves and leave a sticky substance behind. The only beneficiary of this process is ants, who harvest the sticky sweet stuff.
  • The best solution to aphids is to import ladybugs to your garden. They feed on aphids and are very effective in ridding your plants of these little green, gray, or brown bugs.
  • Another solution is to spray them off with a hose and high-pressure spray nozzle or an organic insecticidal soap.

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ENVIRONMENTAL FACTORS

  • Summer squash seedlings may be affected by a group of fungi that cause “damping off.”
  • Damping off fungi will attack the seeds, seedlings or very young plants and cause a type of rot to infect the roots or base of the plant causing sudden growth and collapse in usually (in our experience) under a day.
  • If you’re planting in trays, use sterile potting soil, sterile trays, and avoid using your gardens soil.
  • You can sterilize potting soil by getting it very wet and placing it in a metal container in an oven and heating it to around 160°F for about 30 minutes; the oven should be heated to around 200°F.
  • Use a meat thermometer to check the temperature, and turn the oven down a bit if the temperature exceeds 165°F.
  • Cool the soil to at least 90°F before planting your seeds in it.
  • Also be aware that too much moisture is often part of the cause of seedlings damping off.
  • Water your plants with warm water as cool temps tend to encourage damping off fungi.
  • Powdery mildew is another mildew that can affect your winter squash plants, but looks entirely different. It’s whitish and powdery and grows on squash leaves and stems.
  • It is caused by wetness, but with warmth and humidity rather than cool weather and rain.
  • If the leaves are infected, they’ll usually die. If the infections is severe, it can kill the whole plant.
  • If you are able to, avoid overhead watering. If not, water early in the morning so the plants can dry out by noon or so.
  • If you keep insect pests under control and spray your vines and leaves with a compost tea solution or a baking soda solution, you most likely won’t have an issue with this disease.
  • Other solutions include organic sulfur sprays or a weak solution of milk and water (9:1).
  • If you spot any of this mildew, destroy your vines at the end of the season and rotate your winter squash to a new area next gardening season.
  • You can also purchase seed varieties that are resistant to fungi such as downy and powdery mildews.
  • Bacterial Wilt is a disease that’s spread by infected cucumber beetles.
  • As these beetles feed on leaves, the wounds which have the bacteria begin to create other areas of dull green patches.
  • Bacterial wilt can spread rapidly to the entire plant within a couple of weeks.
  • Controlling cucumber beetles is the best defense against bacterial wilt. Row covers are an effective deterrent if sealed around the edges of the covers with dirt.
  • If a plant is infected, pull it up and dispose of it immediately; if it’s intertwined with an uninfected plant, kill the infected plant and let it die and dry.
  • Rotate your crop out of the area next season. Rototill all squash, melon, and cucumbers under in the fall to reduce cucumber beetle overwintering areas.

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4 Responses to “How To Grow Organic Summer Squash”

  1. benjamin ballmer Says:

    i have butternut squash that got bacterial wilt. There were some nice sized squash on the vine so I pulled those and then pulled out the vine and disposed of it. Will those squash that I pulled still change color and be good to eat or are they not safe to eat anymore?

  2. Barry Says:

    Benjamin, it will depend on how ripe the squash were when the plants contracted the bacterial wilt. If the skin turns a light brown color and is almost impenetrable with your thumb or fingernail, it should still be edible.

  3. Megan Says:

    This is a great article — I’ve been fighting cucumber beetles almost all summer and they’re wearing me out! Do you have any other recommended organic controls for them, besides row covers? I’ve been hand squishing but it’s just taking up too much time and isn’t getting them sufficiently under control.

  4. Barry Says:

    Megan,

    You can use “beer bowls,” but those can take some time to set up and you run the risk of getting your cat or dog drunk 😉

    If you bury your bowl with the rim at about surface level, bugs always like beer over squash leaves and will drown in it (sounds like some guys I know).

    Diatomaceous Earth is another probable solution and is completely organic…it’s available at many garden stores. The drawback with DE is you have to keep your powder dry or re-apply. It doesn’t work when it’s wet and dew can dampen it as well.

    A third option, though you need to make sure you get the organic kind, is pyrethrum (a.k.a. pyrethrins). Usually comes in a spray bottle or concentrate form to mix into a spray bottle. We’ve used this successfully with many pests, but it will take out your pollinating insects as well, so it’s advisable not to use it when your plants are flowering. Also available and many garden stores.

    Good luck!

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