How to Grow Zucchini (Summer Squash): Planting, Pests, Pollination & More
It almost feels funny to write about how to grow zucchini, because summer squash quite often grows like a weed – providing more fruit than you can keep up with! Around here, our neighbors even like to play “ding-dong-ditch the zucchini”. On the other hand, some gardeners struggle to grow healthy zucchini for one reason or another. Maybe disease or pests wreck havoc on your plants, or the squash shrivel up and die before they mature. I think I can help with those issues, and more!
Read along to learn how to grow zucchini and other similar summer squash plants. We’ll go over tips and best practices from seed (or seedling) to table. With the right growing conditions, pollination, and pest control – you’ll be playing your own games of ditch the extra zucchini in no time! Or better yet, check out our top 4 favorite summer squash recipes to use up the glut of zucchini you are soon bound to have. Pesto zoodles, fiesta-style stuffed squash, parmesan zucchini fritters, or zucchini sourdough anyone?
Choosing Squash Varieties to Grow
There are dozens of fun and unique varieties of summer squash to grow at home. In the grocery store, you’ll most likely see just the usual suspects: straight green zucchini, and perhaps yellow crookneck squash. Zucchini itself has many variations, including some with stripes (cocozelle type), others that are yellow or grey, and more. Summer squash can also be round like a baseball or slightly flattened like patty pan.
Even though one squash plant has the ability to provide more than enough zucchini for a small family, we always grow at least 2 or 3 (or 4!) plants at a time. There are too many interesting options to grow only one. Furthermore, having a second partner plant around increases the chances of pollination. We’ll talk more about the importance of zucchini pollination in a moment.
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Our favorite summer squash varieties
We select varieties based on their description (e.g. what sounds good to eat?), natural disease resistance, and previous success in our garden. We experiment with new-to-us varieties from time to time, and I encourage you to do the same! On the other hand, we have a few trusted go-to varieties:
- Dunja Zucchini. This is a super-prolific, early, green zucchini that is naturally resistant to powdery mildew. It does excellent for us here. The leaves also have a really awesome shape and pattern.
- Butta Squash aka “Cube of Butter”. A very prolific straight summer squash, aptly named for its smooth creamy texture and light yellow color.
- Zucchini Gray. Come to think of it, these remind me of Butta squash – but pale greenish grey rather than light yellow. They’re slightly more fat than classic zucchini, but don’t get overly seedy or pithy in the middle until they’re huge. Also very prolific, and pretty!
- Dario. This is a Cocozelle-type zucchini, meaning it has really awesome light and dark green stripes. It also has the tendency to stay slim as it gets long, rather than fat and seedy like some zucchini can. This particular cocozelle variety is also somewhat naturally resistant to powdery mildew.
- White Bush Scallop. I love these adorable lobed white fruit! Patty pan are especially fun to cut into “fillets”, marinate, and grill in the summertime.
What is the Difference Between Summer Squash and Winter Squash?
Despite the misleading name, winter squash is grown during the summertime – just like summer squash. The main difference is that winter squash, also commonly referred to as “hard squash”, last longer in storage. Summer squash are more perishable. That means you can enjoy hard squash (such as butternut, acorn, pumpkin, or spaghetti squash) during the winter time, long after harvest in the late summer or fall. On the flip side, summer squash like zucchini is best enjoyed soon after harvest – unless it is somehow preserved.
Another notable difference is that summer squash and zucchini grow on bushy plants, while winter squash usually grow on long sprawling vines. Therefore, winter squash take up more room but can be trained up trellises or arches to save space. You can also grow zucchini along a trellis, but it doesn’t climb quite like winter squash does. Finally, hard winter squash takes longer to cook than tender summer squash because it is… well, hard. Otherwise, many of the tips for growing summer squash also apply to hard squash.
Growing Zucchini From Seed or Seedlings
Direct sow or start indoors?
Squash is one of those plants that doesn’t like its roots ruffled. Therefore, many gardeners simply direct-sow squash seeds outside once the soil warms enough to do so in the spring. If you do start them indoors, it is important that young squash seedlings don’t get root bound or too large inside their containers. You’ll also want to take care to create as little disruption as possible when transplanting squash outside.
We start our squash inside to give the plants a little head start, but take several measures to keep them happy. For example, we sow the seeds only 3 to 4 weeks before they’ll be planted outside, and do so in large 6” seedling pots. We fill the pots most of the way with quality potting soil, and then add a small amount of seedling soil mix in the center where the seed is planted. This way, the squash seedlings have plenty of space and nutrition, and also will not need to be potted up before going outside. Remember to harden off seedlings before transplanting from inside to outside! See this article for more indoor seed-starting tips.
Sowing seeds & thinning seedlings
Whether sowing directly outdoors or inside in containers, plant squash and zucchini seeds 1 inch deep in the soil. Lightly cover, water, and keep the soil moist to assist in germination. Most will pop up within a few days of planting. We typically sow a couple seeds in each container, but thin them down to one seedling per pot after sprouting by cutting (not pulling) the unwanted seedling out.
If you want to grow zucchini from purchased seedlings rather than from seed, choose the smaller and more tender-looking squash seedlings at the local nursery! Bigger is not alway better, especially in the seedling world.
SUMMER SQUSH GROWING CONDITIONS
If you aren’t sure when to start squash in your zone, refer to your Homestead and Chill garden planting calendar! Most zucchini and summer squash require an average of 50 days from the time of planting seeds to harvest fruit. Read the seed package or description of each variety for their unique “days to maturity”. Once they begin to bear fruit, you can continually harvest squash (sometimes many per week!) for several months – until the plant naturally declines due to time, disease, or climate conditions.
Because squash are so quick to mature, you may be able to “succession plant” and have several rounds of squash from spring until fall. If squash vine borers are a big problem in your area, you may want to wait to plant squash until early to mid-July. See the pest & disease section below for a deeper explanation why.
Zucchini and other summer squash prefer warm summer-like growing conditions. An ideal time to grow zucchini is when the air temperature is in the 70s to low 80s, and the soil is also nice and warm – at least 60°F. They will continue to grow in cooler conditions (albeit more slowly) as long as it is not freezing. Our summers are very mild and foggy, and squash still does quite well here! Alternatively, fruit production can decrease when temperatures are over 85°F. Because of this, consider growing summer squash in the spring and again in fall in locations with extremely hot summers.
Squash like full sun, and will not grow well in full shade. Yet in the hottest climates, your squash plants may appreciate partial shade in the afternoon. Provide 6 to 7 hours of sun per day at minimum.
Soil & Fertilizer
Zucchini grow mostly happily in soil that is fertile and rich with organic matter, but is loose and well-draining. Add compost and/or worm castings to their planting area to increase organic matter content. We also lightly amend our raised beds with mild, slow-release fertilizers such as kelp meal, alfalfa meal, and/or neem seed meal between growing seasons (twice per year). For more details about how we prepare and amend our no-till raised garden beds before planting, see this article.
Provide your zucchini plants plenty of space! Each bushy summer squash plant can extend outwards a couple feet in every direction. When overcrowded, squash are more susceptible to pests and disease due to lack of air circulation and increased competition for sun, nutrients and water. I typically space squash plants about 2 to 3 feet apart, or at least 2 feet away from other types of more compact plants.
Like many plants, zucchini grow and lean towards the sun. For us in the Northern Hemisphere, this means towards the south and west. I like to keep this in mind when choosing where to plant squash amongst other vegetables and companion plants in a raised garden bed. For instance, I leave plenty of space “in front” of the squash plant (towards the sun) where it will fill in most, but can plant things a tad closer in the back.
If you don’t have room in your garden beds, zucchini and other squash grow well in containers too! Because they have wide shallow root systems, large wide containers are best over deep narrow ones. We have successfully grown healthy zucchini plants in these 10-gallon grow bags.
SUMMER SQUASH ONGOING CARE & SUPPORT
Squash and zucchini grow shallow and wide-reaching roots. They appreciate consistent moisture, but not soggy soil or standing water. It is not uncommon for squash to look a little droopy during hot afternoons. If the soil is already quite damp, resist the urge to add even more water. They’ll perk up once again in the evening. Because of their sprawling root structure, we like to water and dampen the soil all around the plant canopy, not only at the very base of the plant. Squash will also benefit from a nice layer of mulch to help prevent the top layer of soil from drying out.
Once established and bearing fruit, squash plants will appreciate being fed once or twice throughout the growing season. In addition to the initial compost and amendments provided at the time of planting, we fertilize our crops with mild natural fertilizers such as dilute seaweed extract, stinging nettle tea, or compost tea. You could also use a gentle slow-release all-purpose fertilizer.
Have you ever tried to grow zucchini and the baby squash starts to develop, but then all of the sudden it turns brown at the end and rots? We can fix that! The likely cause of this particular predicament is a lack of pollination.
In order for squash and zucchini to grow large and healthy, their flowers MUST be pollinated.
More specifically, pollen must be transferred from an open male zucchini flower to an open female blossom. Furthermore, a male bloom from one variety of summer squash can be used to pollinate the female flower of a different variety of summer squash. The same applies between different varieties of winter squash as well. The seeds can’t be saved from cross-pollinated squash since it will not “breed true” when grown later. However, cross-pollination among varieties is difficult to prevent, and is very common among home gardens where several types of squash are grown.
If you have plenty of bees in your garden, they may pollinate the flowers for you. On the other hand, you may find the need to hand-pollinate zucchini and squash blossoms yourself. It is quite easy to do! We have a ton of bees around but still hand-pollinate our squash blossoms, simply to guarantee successful fruit development. To learn more about how to hand pollinate zucchini or squash blossoms, see this article all about “squash sex”. A quick demo video is included!
SUMMER SQUASH PESTS & DISEASES
Zucchini and summer squash can be inflicted by a number of pests. Some of the most common and bothersome include squash bugs, squash vine borers, and mildew. We’ll talk about each of those in detail below.
Squash plants may also become infested with aphids. Check the underside of the leaves for aphids, where most pests are found in general! The easiest way to deal with aphids is to simply blast them off with a stream of water. If the problem persists, you can also try this gentle DIY soap spray recipe. It is effective against all small soft-bodied insects including aphids, mealybugs, spider mites, psyllids, white fly and scale.
Another option is to routinely treat your squash plants with neem oil to kill and/or deter pests and disease, including fungal disease and mildews. Neem oil is a great tool in an organic garden, but only if used correctly! Learn how to properly mix and use neem oil here, and sever other organic ways to prevent or treat powdery mildew here.
Squash bugs, not to be confused with squash vine borers, are quite common throughout North America. Thankfully, they’re not quite as damaging as vine borers!
Squash Bug Damage
Squash bugs are sap-suckers, like aphids and whiteflies. Yet, in addition to sucking on leaves, their piercing mouthparts also inject a toxin into the foliage. This leaves spots that will yellow, then turn brown and crispy. It can also cause foliage to wilt. The damage done prevents the plant from adequately using nutrients and water for optimal health.
Identifying Squash Bugs
Adult squash bugs can be up to half an inch long, with a brown or grey flat body. Young baby squash bugs will cluster on the underside of leaves, and look similar to large aphids, with grey bodies and long black legs. The adult beetles are commonly found under damaged leaves. They will also congregate under wood on the soil surface, and in deep cool mulches of straw or hay.
How to Prevent or Kill Squash Bugs
- Manual removal: Inspect the underside of zucchini and squash leaves for clusters of squash bug eggs, as shown above. Then simply scrape the eggs away with a butter knife or similar tool and dispose of them (not in your garden)! Similarly, you can collect or smash adult squash bugs when you see them. I have also heard of people vacuuming them up!
- Set traps: Because squash bugs like to hang out in the dark under debris, you can create traps that simulate those conditions. For example, place a flat board or piece of wood on the soil surface overnight, and then scoop them into a bucket of soapy water for disposal in the morning.
- Plant Resistant Varieties: Early yellow crookneck, Butternut squash and Acorn are all supposed to be less attractive and/or more resistant to squash bugs.
- Physical Barriers; Use fine-mesh floating row covers over your plants to stop the insects from accessing them. Row covers can be either laid directly on top of plants or supported on top of hoops. Be sure to tuck them in tightly around the edges! If you use row covers over squash, you’ll need to get in there and hand-pollinate the flowers yourself since the bees will not be able to access them.
Squash Vine Borer
One of the top questions I get asked about growing zucchini is “how do you deal with squash vine borers?!” I cringe and feel like a jerk when I reply “We actually don’t get them here on the West Coast!”… Sorry guys, but it’s true. Squash vine borers are most common in the eastern and southern US states. However, I’ve done a bit of research on squash vine borers so I can still help provide you with tips and answers!
Squash Vine Borer Damage
As their name suggests, these pests bore into the vines of squash plants. Young borer larvae will cause similar leaf damage as squash bugs, including yellowing and wilting. Adult vine borers burrow into the large hollow stems of squash plants, eating them from the inside out. Wilting plants is usually the first symptom. Some squash plants wilt naturally in hot afternoon sun, but if it doesn’t spring back in the evening time, it may be a squash vine borer at work.
Identifying Squash Vine Borers
An adult vine borer insect (a moth) may be confused with a wasp, with a similar body structure. They are about a half-inch long, orange with black spots, and have long wings. In addition to wilting, you may notice holes in the stems near the base of the squash plant. Also, an accumulation of greenish saw-dust like material may be visible. This is called frass, aka, their poop.
How to Prevent or Kill Squash Vine Borers
- Squash vine borers can be hard to manage. Once they’re inside the vine, it is very difficult to treat or help the plant. It is possible to cut them out of the stem with a knife, though it may not save the plant. Dispose of infected plants – and not in your compost!
- Squash borers are most active during June and July. Therefore, one management technique is to plant squash crops in mid-July or later. The plants will mature when the adult borers are no longer active. If you have a short growing season, look for squash varieties with the fewest days to maturity to ensure the plants produce before your first frost.
- If vine borers are in your garden, try creating traps by filling a yellow container (yellow bowl, pail, dish, etc) with water. They’re attracted to the color yellow (like a squash blossom) and will hopefully get stuck in the water. Be sure to empty the traps daily.
- Cover the exposed portion of the squash plant stem/vine with mulch, making it less accessible to the borers. I have even heard of some people wrapping the stems with tin foil. You can also try to keep vine borers out of your plants with hoops and floating row covers over them.
- Practice good crop rotation. Vine borers hibernate over winter in cocoons within the soil near the plants they infected the previous summer. Meaning, if you grow zucchini in the same location that you previously had squash plants or a vine borer infestation and then place a row cover over it, they may emerge from the soil below and become trapped inside – rather than being kept out. You’ll also need to hand-pollinate the squash blossoms.
- Plant Resistant Varieties. Squash varieties in the Cucurbita moschata family are known to be less attractive and/or more resistant to squash vine borers, including Walthum Butternut, Blue Hubbard Squash, and Tromboncino. I’ve heard the same for Italian Cocozelle.
- If you have any more tips and tricks for dealing with squash vine borers, please leave them in the comments at the end of this post! For more information about vine borers, see this helpful article.
Squash plants are susceptible to unsightly and annoying infections of powdery mildew. Downy mildew can also affect them, though it isn’t quite as prevalent as powdery mildew. Both fungal diseases spread through spores on the leaves, which cause irregular color spots and/or a coating of white fuzzy-looking mildew. Thankfully, the infections are not usually fatal to plants except in extreme cases). Yet mildews do impact overall plant health and production, and can easily spread to other plants in your garden.
Identifying Powdery Mildew and Downy Mildew
Powdery mildew looks like white, fuzzy, and slightly raised irregular spots on leaves. The worse the infestation gets, the thicker and more “powdery” it becomes. Catching a mildew infection early gives you the best chance to successfully treat and stop it. Powdery mildew often appears on the undersides of leaves first, so we make an effort to routinely inspect our plants – including the bottom of leaves. On the other hand, downy mildew creates small yellow spots on leaves that eventually turn brown, thin, and crispy.
A note about natural leaf patterns
Keep in mind that not all “white spots” on squash leaves are mildew or disease! Many squash (and melon) varieties have natural variegation and patterns on their leaves. Check out the photo of our very healthy Dunja squash plant below! That is not mildew.
How can we tell the difference? Well, the natural speckles and white spots are usually fairly uniform, displayed in a mirrored pattern across all leaves and either side of a vein. It is also only on the top side of the leaf. In contrast, powdery mildew will likely appear on both the top and bottom of the leaves and in more irregular patterns – some big spots, some little spots, and some leaves with none at all.
How to Prevent and Control Powdery Mildew on Zucchini and Squash
- Provide ample space between plants to provide good air circulation. Mildew is more prevalent and spreads easily in cramped and moist conditions.
- Prune away infected leaves, or remove severely impacted plants entirely. Remember to clean your pruning shears well (e.g. with rubbing alcohol) between cuts and working between plants, and avoid composting the plants to prevent spreading disease.
- Choose naturally disease-resistant varieties. When we seed shop for squash and zucchini, we are always on the look-out for notes about mildew resistance in their descriptions. Dunja zucchini is our PM-resistant rock star!
- There are all sorts of homemade organic spray recipes out there said to combat mildews. For example, mixing milk with water, or using dilute neem oil spray on a routine basis. Truth be told, we’ve tried both with mixed results. Neem oil does help slow the spread but doesn’t kill mildew completely, and requires cumbersome weekly applications to every inch of the plants.
- The easiest organic solution that we have found to prevent and control powdery mildew in our garden is using Green Cure. The active ingredient is non-toxic potassium bicarbonate (similar to baking soda, minus the sodium) which effectively changes the pH of plant leaves to make it inhospitable for mildew and blight to grow. Once we had an outbreak of powdery mildew on a whole batch of greenhouse seedlings, treated them twice with Green Cure early on, and it never came back for the entire season! A miracle worker, in my book.
Pruning Zucchini and Squash Plants
To prune or not to prune? That is the question. Zucchini and squash plants don’t necessarily need to be pruned, but there is a time and place when pruning is beneficial. For instance, if select leaves are showing signs of a mildew infection, or to increase airflow around crowded plants. I also like to cut away the old and unsightly leaves as they naturally fade throughout the growing season. In those instances, use clean pruning shears to cut the entire leaf and stem off at the base where it connects to the main vine. Use rubbing alcohol to clean the pruners between cuts. Otherwise, I prefer to mostly leave them alone. When you cut into a plant and expose their usually-protected insides, it can become more susceptible to disease and pests.
Harvesting Zucchini & Squash
When to harvest zucchini and squash
Zucchini and other summer squash are most tender (and arguably most tasty) when harvested fairly small. As squash matures, it becomes more pithy, tough and seedy. Therefore, I suggest harvesting zucchini when it is approximately 5 to 7 inches long. Some varieties stay more tender and slender at even longer lengths. On the flip side, some folks harvest their zucchini very small – with the blossom still intact. Squash blossoms are an edible delicacy. They’re especially delicious stuffed with a savory cheese like ricotta or goat cheese, battered, and pan-fried!
Did you know that zucchini have three major growth spurts per day? Once in the morning, again in the early afternoon, and another in the evening. Zucchini has the tendency to get huge seemingly overnight, especially if it is hidden out of sight under leaves. They literally grow like weeds! If a zucchini monster creeps up on you, it’s all good! We actually let a few get really overgrown each season on purpose, just so we can make our favorite stuffed squash recipe.
How to harvest zucchini and summer squash
To harvest zucchini and other squash, you can gently twist the fruit in a circular motion until it pulls away from the vine. However, there is some risk of breaking the vine or the zucchini itself with that method. If the top of the zucchini breaks near the stem (exposing the flesh), it will go bad far quicker in storage. Thus, we prefer to use clean garden pruners, scissors, or a knife to carefully cut the squash at the stem instead.
Here is a little harvest demo video from my Instagram:
And then, it is time to eat!
Eating & Preserving Zucchini
The mild flavor of zucchini and summer squash makes them extremely versatile to use in many recipes. Sautéed, roasted, grilled, on pizza, in soup, stir fry, pasta salad or lasagna… the list goes on! More often than not, we toss fresh sliced zucchini in our trusty cast iron wok with some extra virgin olive oil, garlic, onion, other seasonal veggies, and seasonings of choice. But when our garden provides an abundance of squash, we’ve also found several creative and flavorful ways to make use of excess zucchini too!
Please enjoy our favorite garden-to-table zucchini recipes:
- Fiesta-Style Wild Rice, Bean, & Veggie Stuffed Squash
- Pesto Zoodles: How to Make the Perfect Zucchini Noodles
- Easy Parmesan Zucchini Fritters w/ Healthy Yogurt Dill Sauce
- Zucchini & Walnut Sourdough Bread Recipe
If you’re a fan of making zucchini bread, an easy way to preserve zucchini is to grate and freeze it in portions for future bread.
And that concludes your ultimate crash-course on how to grow zucchini.
In all, I hope this article took some of the mystery out of growing zucchini and other summer squash for you. Especially if you were having issues with pollination! I think learning that trick that was our biggest “ah-ha” moment when we first began to grow zucchini in our garden. Please let me know if you have any questions, and feel free to spread the love by sharing or pinning this article. Also let us know if you try our zucchini recipes by leaving a much-appreciated review! Happy first day of spring!
Hi! I am finding that my zucchini flowers are shriveling up/falling off before I have a chance to hand pollinate. Any thoughts on why this is happening? I planted them in large pots with full sun and moist but not wet soil. Zone 7b
Aaron (Mr. DeannaCat)
Hi Tara, how old are your squash plants as it is common for younger plants to produce flowers that fall off quickly until the plant matures more. Are the flowers male or female? If they are female flowers, are the squash continuing to grow after the flower falls off or are they un-pollinated fruit that shrivel at the blossom end shortly after? If the male flowers are the ones falling off, you can still tear open the flower to get to the pollen inside. Hope that helps and let us know if anything else comes up, good luck!
We have tried multiple varieties of summer squash with pitiful results. Recently the female flowers, with fruit attached, never open so we can hand pollinate. This is on mature plants in July
Thus, no development. We’re missing out on what should be an easy to grow crop. Any help with the flowers that don’t open?
Aaron (Mr. DeannaCat)
Hi Chuck, be sure that you are checking the flowers in the morning as that is the time they are most apt to be open. If the plants are stressed due to the daily temperatures being hot can also cause the squash plant flowers to not open. If the flowers are closed and the fruit isn’t premature, open the flowers by hand and pollinate them that way to see if they will take. Another issue that may be stressing your plants would be if you have squash vine borers. Hope that helps and good luck!
Could you provide another source for the Green Cure? The supplied link is broken.
Aaron (Mr. DeannaCat)
Hello Melissa, here is what we are using now as Green Cure is no longer in production. We have a more in depth article on How to Prevent or Treat Powdery Mildew Organically and we describe how to properly mix the potassium bicarbonate for a foliar spray. Hope that helps and good luck!
“…we cut away the unwanted seedling.”? why? you can simply separate them and plant them both. Or plant one seed into one container.
Aaron (Mr. DeannaCat)
You can do that however we don’t have enough space to plant all the squash that may sprout. We also plant more than one seed in case there is an issue with germination, if the seeds are older our chances of it sprouting are greater. Also, most seed companies sell their seeds for a very affordable price and we enjoy supporting those businesses for the work they do.
Best companion plants for zukes?
Aaron (Mr. DeannaCat)
Hi Juliana, check out our Companion Planting 101 (w/ Garden Companion Planting Chart) article. Corn, lettuce, marigolds, nasturtiums, peas, melons, beans and peppers are all great. Marigolds and nasturtiums can help with pest prevention. Good luck!