How to Grow Summer Squash Vertically - GreenStalk Garden

How to Grow Summer Squash Vertically

Summer Squash Fast Facts

Cool or warm weather: Warm 
Size: Large
Sun: 8 hours
Days til maturity: 55-75 days
Water: Consistent
Original or Leaf GreenStalk: Original
GreenStalk level: Place below smaller plants
Plant support needed? Yes

Summer squash is a short-season, prolific grower which, as its name implies, loves summer warmth and full sun. There are a few pests to watch out for but nothing that can’t be controlled if cared for properly. Zucchini, crookneck squash, and classic straightneck yellow squash are all members of the cucurbit family and grow similarly, so we’ll address them all together.

Straightneck yellow squash growing in a limited edition Glacier Blue GreenStalk Planter.

Planting & Growing

Summer squash seeds tend to germinate quickly and easily. They can be started outside when there is no risk of frost and the soil has warmed up to at least 70°F (21°C). Expect about 55-75 days from seed to harvest. Keep the soil consistently moist throughout the growing season – squash doesn’t love to dry out between waterings and can result in misshapen fruits or even blossom end rot. The best way to tell is by pushing your fingertip into the soil down to your first knuckle and if you don’t feel moisture, it's time to water!

Always fill your GreenStalk with quality potting soil to give your plants a great start. Once your plants start flowering, you can add a liquid fertilizer as you water through the reservoir. Follow dilution instructions on the fertilizer packaging.

Supporting your squash

The GreenStalk Original Vertical Planter is recommended for all summer squash varieties, with one plant per pocket and spacing every other pocket for plant growth. There are many possibilities for supporting your squash. Our GreenStalk Plant Supports are a great option for supporting a whole tier at once.  You could also stake them with a bamboo cane in the pocket, tying up the vine to the cane as the plant grows. Another fun alternative is to use GreenStalk Plant Markers. Simply run twine through the loop at the bottom creating a little “hammock” to support plant growth!

Pests & Disease

Growing summer squash, you will quickly become familiar with pesky squash bugs. They can be detected early if you check the leaves thoroughly for eggs and remove them. Shiny orange/rust-colored eggs are laid in clusters under the leaves near the veins. You can scrape them off carefully, trying not to damage the leaf, and drop them in a small cup of soapy water. Hand-pick any nymphs or adults; they’re hard to miss if you check regularly.

Squash vine borer adults are moths that leave inconspicuous eggs near the base of the plant. The larvae immediately bore into the stem causing damage from the inside. If your plant is wilting, look for a mushy spot on the stem. Take a sharp, clean knife and slice a couple of inches along that spot a pull out the white larvae. Mound the soil over that spot and direct water so the plant can heal. It sounds intimidating but it’s not difficult! The good news is most egg-laying is complete by late June, so a crop started in early July should not be affected.

You could use an Insect Protection Cover but only until flowers appear. You don’t want to keep out friendly pollinators!

Powdery mildew may become a concern. To help prevent it, move your GreenStalk into an area with full sun and good airflow, which is easy with the GreenStalk Mover! You can also spray the leaves with neem oil to prevent the powdery mildew from traveling to nearby plants.

A note on pollination

Summer squash will bear little to no fruit if not pollinated. Bees will certainly help you. However, you can also hand pollinate by using a clean paintbrush to transfer pollen from the male flowers to the female ones. Male flowers have a thin stem and do not produce fruit, while female flowers come from a thicker stem which is actually an immature fruit. 

Zucchini squash growing in a limited edition Glacier Blue GreenStalk.


Depending on the variety, most summer squash can be harvested when it reaches six to eight inches. Large squash tends to have less flavor and a tough exterior. Use a sharp knife to cut it from the vine. It's no fun snapping your fruit in half trying to pull it by hand! You can also harvest the squash blossoms! Stuff them, fry them, or add them as a gorgeous garnish. They’re delicious!

Refrigerate for up to ten days, or slice, blanch, and freeze them for up to three months. Or pass some along to a neighbor … August 8 is National Sneak Some Zucchini Onto Your Neighbors Porch Day!

We hope you’ll give summer squash a try in your GreenStalk Vertical Garden! For more information about growing in your specific climate, check out your local extension office. We’re here to help you grow — just email us at

Happy gardening!


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