Zucchini growing problems strike every gardener. Learn how to overcome them.

Zucchini growing problems: 10 common issues and how to overcome them

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Zucchini and other soft-skinned summer squashes are usually pretty easy to grow. But, gardeners do sometimes face struggles with these productive crops. Perhaps your vines stopped producing in mid summer? Or the fruits were small or deformed? Or maybe your plants simply died before producing any fruits? If you found yourself asking why zucchini growing problems struck your garden, this solution guide is for you.

Top 10 zucchini growing problems

Here are ten reasons why you may have faced zucchini growing problems in the past, and tips for making sure these issues don’t happen again.

Zucchini problem 1: Improper variety selection.

Not all zucchini varieties perform the same. Some are more productive than others, and some are more disease- and pest-resistant. First and foremost, when selecting zucchini varieties for your garden, be sure to seek out disease and pest resistance whenever possible. Varieties with a high level of natural resistance often perform better and produce longer. ‘Tigress’, ‘Green Machine’, ‘Burpee Golden Glory’, and ‘Yellow Fin’ are great choices.

The best disease resistant zucchini varieties.

Limiting zucchini growing problems starts with selecting the right varieties.

Zucchini problem 2: Squash vine borers.

One of the biggest zucchini growing problems is a pest known as the squash vine borer. Adult vine borers are day-flying moths that are black and red with dark wings. They’re fast flyers, so gardeners don’t often spot them. The damage caused by their larvae, however, is difficult to miss. Squash vine borer larvae feed inside the main stem of the plant, hollowing it out and eventually causing plant death. You’ll see crumbly, sawdust-like waste collected below a small hole at the base of the plant. To prevent squash vine borers, protect the lower portion of the stem with a wrap of aluminum foil (more on this technique here), or cover the plants with floating row cover until they come into bloom to keep the female moths away from egg-laying sites.

Squash vine borers are challenging zucchini pests.

Adult squash vine borers are day-flying moths that look like large wasps.

Zucchini problem 3: Poor pollination.

Zucchini and other squash are insect pollinated, meaning a bee, beetle, or other pollinator is needed to move the pollen from a separate male flower over to a female flower. If there aren’t enough pollinators present, puny or deformed fruits are the result. If your zucchini are mal-formed and stubby on the blossom end, poor pollination is the most pressing of your zucchini growing problems. To improve pollination rates, plant lots of flowering herbs and annuals in and around your zucchini patch. You can also hand-pollinate the vines by using a paintbrush or your fingertip to transfer pollen from the male flowers to the females (more on how to hand pollinate here). Another option is to plant a parthenocarpic variety that doesn’t require pollination to set fruit, such as ‘Easypick Gold’, ‘Partenon’, or ‘Cavili’.

Zucchini pollination problems.

Zucchinis rely on insect pollinators to move the pollen from male to female flowers.

Zucchini problem 4: Powdery mildew.

Powdery mildew is among the most pervasive fungal diseases when it comes to vine crops like zucchini. This pathogen makes the leaves appear to be covered in a talcum powder-like coating. Though it’s primarily an aesthetic issue, severe cases can lead to reduced photosynthesis and reduced production. To overcome powdery mildew, space plants properly – give each one plenty of room so air can circulate and dry off wet foliage. Plant only resistant varieties, such as ‘Anton’, ‘Dunja’, ‘Astia’, and ‘Emerald Delight’, to help combat powdery mildew which is one of the most tenacious zucchini growing problems. Organic fungicides based on potassium bicarbonate (such as GreenCure and BiCarb) are effective as preventatives, as are those based on Bacillus subtilis (such as Serenade).

Powdery mildew is a difficult zucchini growing problem to tackle.

Powdery mildew is a difficult fungal disease that often strikes zucchini plants.

Zucchini problem 5: Squash bugs.

When it comes to insects that attack squash, none are more difficult to control than squash bugs. These shield-shaped, brown insects suck out plant juices with their needle-like mouthpart, causing stippling, yellowing, and browning of the leaves.

Squash bugs are one of the worst zucchini growing problems a gardener can face.

Squash bugs are first seen as clusters of bronze, football-shaped eggs followed by gray nymphs that feed in groups.

The best way to manage squash bugs is to head to the garden every day and inspect the top and bottom of your zucchini leaves for clusters of bronze-colored, football-shaped eggs. Squash bugs are resistant to most pesticides, but very young nymphs can be controlled with applications of insecticidal soap or horticultural oil. Our Guide to Vegetable Garden Pests has more info on this troublesome insect.

Watch this video to see a cool trick for getting rid of squash bugs organically – using duct tape! 

Zucchini problem 6: Poor soil.

Zucchini doesn’t require excessively nutrient-rich soil, but it does perform best in soils that are high in organic matter with a soil pH around 6.5. If your pH is too far off that target mark, the plants may fail to produce quality fruit because the soil pH affects the availability of many different nutrients (more on soil pH here). You can also prevent many zucchini growing problems related to the soil by limiting the amount of nitrogen you add to your garden. Excessive nitrogen produces a lot of green leaves, often at the expense of good fruit production. Use only balanced, organic fertilizers on your zucchini patch and test your soil every few years to ensure it’s healthy and well-balanced.

The best soil for growing zucchini

Give zucchini plants plenty of room to grow and make sure they’re planted in soil that’s rich in organic matter.

Zucchini problem 7: Lack of water.

Zucchini growing problems can also stem from irregular soil moisture levels. If plants are allowed to dry out between waterings, fruit production can be negatively impacted. Drought stress is never good for vegetable crops, and zucchinis require consistent, even soil moisture throughout the growing season. If Mother Nature doesn’t supply your garden with at least one inch of water per week, it’s your job to add supplemental irrigation to prevent any possible issues. A 2-3 inch thick layer of mulch helps stabilize soil moisture levels and can reduce the need to irrigate during the hot summer months. You’ll find more information on proper mulching techniques here.

Mulch is essential to a healthy zucchini crop.

Mulch zucchini well to keep the soil evenly moist. This zucchini patch is mulched with newspaper topped with shredded leaves.

Zucchini problem 8: Blossom end rot.

Zucchini can also be affected by blossom end rot, just like tomatoes and peppers. This physiological disorder causes the blossom end of the fruit to rot into a dark, sunken canker. It’s caused by a calcium deficiency, but it’s the result of inconsistent watering. Calcium can only come into a plant as it absorbs water in through its roots. When there’s no water in the soil to absorb, the plant can’t access calcium either and blossom end rot is the result. To prevent blossom end rot from striking your zucchini, make sure the plants receive ample, consistent applications of water throughout the growing season. Adding more calcium will not solve the problem.

Zucchini problem 9: Bacterial wilt.

Though this pathogen tends to be more problematic on cucumbers, it sometimes strikes zucchini as well. Sadly, this is one of those zucchini growing problems that’s the kiss-of-death when it strikes. Spread by the cucumber beetle, bacterial wilt causes otherwise healthy plants to wilt and die without prior warning. To combat potential problems, keep cucumber beetles in check by trapping them on yellow sticky cards fastened to stakes just above the tops of the plants.

Zucchini are not without their fair share of problems.

Growing healthy, productive zucchini happens when you provide plants with everything they need.

Zucchini problem 10: Not enough sun.

Though it isn’t the worst of the zucchini growing problems you might face, lack of sun can definitely affect plant health and production. Zucchini plants need a minimum of six to eight hours of full sun per day. Lower light levels can result in long, lanky plants with pale green foliage and reduced yields. Poor pollination can also be a side effect of light levels that are too low because pollinators tend to prefer foraging in sunnier areas, particularly on cooler days. Select a full-sun site when planting your zucchinis.

Some zucchini growing problems can be attributed to low sunlight.

Zucchini plants require six to eight hours of full sun per day to perform their best.

Zucchini growing problems don’t have to decimate your crop

Though zucchini growing problems may strike your garden from time to time, with these management tips, you can manage the issues organically and enjoy bushels of delicious zucchini all season long.

For more on growing healthy zucchini, check out these related posts:

Cucumber plant problems
Guide to Vegetable Garden Pests
A Handy Guide to Harvesting Vegetables
Types of Landscape Mulch
A Compost Guide

What challenges have you faced with your zucchini crops and how did you overcome them? 

Pin it!10 Common Zucchini Problems and How to Manage Them Organically

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56 Responses to Zucchini growing problems: 10 common issues and how to overcome them

  1. albert wood says:

    Hi ?I enjoyed reading about the three new vegetable plants, IE: Tomato Valentine; Tempest Summer Squash; and American dream Corn.
    My question could I purchase a small quantity of these seeds to grow in my small back yard garden.
    my garden measures 4 feet wide x 35 feet long.
    I’ve been growing tomatoes on my patio, and zucchini and Swiss chard long with small finger potatoes in my garden. I’d enjoy trying my hand at growing some new plants, f seeds were available and reasonably priced. I’m 78-years-old and currently in the process of recovering from a stroke, hoping to have ability to work in my garden this coming spring and always enjoy eating fresh vegetables., I’m looking forward to receiving your valued reply and comments.
    Sincerely,
    Albert

  2. David Hubbard says:

    found this very interesting

  3. Laura says:

    Our zucchini is growing oddly, they are growing into a narrow finger like instead of the same size if the normal size. I’m sending you a picture. Thank you for any help you can offer. Laura

  4. Wadus Exum says:

    Small grey patches appearing on the leaves of my young golden zucchini plants are growing
    but don’t look sturdy and strong! How can i treat this condition?

  5. Cheryl says:

    Hello Jessica,
    My dad grew zucchinis for a living for a while and was good at it. Unfortunately he has since passed and I cant ask him why my zucchinis don’t grow in size. they look perfect, but don’t get much bigger than my index finger Any thoughts?

  6. Mona says:

    I loved your videos, unfortunately lowes add kept taking me to their patio section. And once there I could not get back to your Pinterest page. I wanted to watch all of your videos but after the third time fighting Lowes ad, coming back and having to start over, I know by heart the duck tape video. I almost saw you talking about rasberry/blackbery, geeze that would have been a good one.

  7. Katie says:

    Brilliant article, thank you!
    I’m having problems with my seedlings as the true leaves are beginning to buckle and crinkle at the end, and the veins and surrounding areas are a whitish/brown colour. Any ideas on what this might be? Thank you!

    • Hmmmm. Sounds like it’s an issue related to the soil. Perhaps a nutrient deficiency or overload. I suggest starting with a soil test to determine if any nutrient levels are out of wack.

  8. Naomi says:

    I use diluted milk and water in a spray bottle for zucchini fungus. It works almost instantly to correct the issue!

  9. Jenn says:

    Hi I have a flower bed with larger rocks maybe 2-3″ all around and then pots dug in. They did more of a container garden with rocks on ground level. Will the surrounding rocks cause any problems for the zucchini plants as they grow and vine out? Thank you

  10. Renee says:

    We are in Southeast TX and started our zucchini plants pretty early (March). They are huge, with leaves the size of a platter. Most of them, however, have all male blossoms with very few females. The female stems we do get are narrow and might be 1-2 inches long and just fall off before we even get to pollinate by hand. We tried pruning the largest leaves to let sun get down to the lower parts, but that only seemed to make it worse. We have little to no female blossoms on 12 plants. It’s a sunny location, well-drained soil. Water lightly once a day. It’s starting to get hot here (90’s highs, 70-75 for lows), so now I fear we may not see any fruit at all. Any suggestions? Is it too late to start all new plants in the ground from seed?

    • Hi Renee – Zucchini are heat-loving crops, so I would suggest starting more plants from seed within the next few weeks. But for the plants you already have, rather than watering shallowly on a daily basis, only water your plants once or twice a week, but aim for a deeper, more penetrating form of irrigation. Shallow irrigation like you’re doing, does not promote a healthy, deep root system which could be stressing the plants and causing the female flowers to abort. Deep watering and a few inches of straw or shredded leaves around the plants will stabilize soil temperatures and moisture levels, and hopefully lead to fruit production.

  11. T. R. says:

    My male zucchini flowers bloomed early, then shriveled and dried out before the female flowers bloomed. Is there anything I can do? Will more male flowers bloom so that the females can be pollinated?

    • Melissa Pitts says:

      You’ll get more males as the plant matures. That’s all very normal. I always lose the first one or 2 to pollination also. I guess the pollinators need a little while to sniff them down since we only have 2 squash and 2 zuke.

  12. joanne i adams says:

    Are both male and female flowers on the same plant? So far all I’m seeing on mine are male.

    • Yes, both male and female flowers are produced on each plant, but the male flowers appear a week or two before the females. Give it some time; the female blooms will be there soon.

  13. vince says:

    why are my zucchini rotting on the ends

    • It’s likely that the flowers were not effectively pollinated, leaving the undeveloped zucchini to rot instead of form full-sized fruits. A fungal pathogen is another possibility, especially if you live in a region that’s had a lot of rain this spring.

  14. Sherry Wong says:

    My zucchini starts to shrivel after it gets about 3” long. What could cause that?

  15. Manilla Adams says:

    My oarents are growing zucchini in pots and they flower and then the flower falls off. No zucchini so far. Any suggestions?

  16. Jessica says:

    Hi! I planted my plants too close together in a raised bed. The plants are large and the stems are all intertwined now. After a recent storm they have been kind of beaten over the edge of the garden bed which is about a foot high. Is it ok to let them continue along the ground? Should I try to support them somehow or is it too late for that?

    • You can definitely let them trail down the side of the bed. They’ll do fine. Just make sure you support the fruits if you plan on letting them grow pretty large. Otherwise, they may snap the vine with their weight.

  17. Megan Puglisi says:

    The flowers on 2 of my zucchinis fell off when the zucchinis were about 3 inches long during a storm. Will they continue to grow without the flower?

  18. Lynne Steketee says:

    This is the second year that I planted zucchini. The zucchini plant is small and flowers. Once the flower dies off the only thing left is a stalk. I am assuming that it is a pollination problem. Is there anything that I can do to help?

    • Sounds like a pollination issue, as long as you’re looking at the female flowers (which are swollen at the base). The male flowers, which only provide the pollen to the female blooms and do not themselves turn into zucchini, will simply drop off, leaving only a stalk behind.

  19. Debbie says:

    I was going for a few days and came back to wilted plants. They perked up after watering but the next day completely wilted looking. Leaves are green but wilted. The main vine looks mushy, would that be a vine borer?

    • Definitely sounds like squash vine borers. You can slice the stem open lengthwise and squish them, then wrap the stem back closed again with a piece of old pantyhose or fabric.

  20. Noureddine says:

    very informative article and easy to follow steps as well, i just started doing gardening and i have no knowledge prior, i planted the Zucchini and i water every three days or two i check by sticking my finger in the soil if moist i don’t water if dry i water. but i was watering everyday when the plants were just small seedlings
    after almost two months the plants are doing good in my opinion considering my first try, i get one zucchini per plant i think every week more is that normal ?
    i also did a test half was planted in a sand soil it’s growth was the best. the second half was planted in muddy soil the growth was bad but i read it prefer the muddy soil am i missing something.
    live in a climate where the lowest is degree of winter is 6C° (42.8 F) and the hottest of summer is 37 C°(98.6 F) i figured i could plant the zucchini almost all year am i wrong?
    hope i didn’t throw too much questions
    Thank you

    • One zucchini per plant each week sounds about right, though it is somewhat dependent on the variety. Production may decrease if you let the zucchinis grow too large. It’s no surprise that the plants in sandier soil did a little better, especially if you’re growing them in containers. They like well-draining soil (which sandier soils are), though they also tolerate clay-based soils quite well, as long as you add plenty of compost or other organic matter to help improve it.

  21. Kevin says:

    It looks like something is cutting stems clean off. I’m not sure if its birds or bugs but i do know its it’s frustrating.

  22. Kate says:

    Hi there. My plants seems pretty healthy except for a few that are producing fruit that looks like it’s bubbling from the inside out. Some of the leaves are now doing the same thing. Like a weird case of warts :$

    • Sounds like your seeds didn’t come true and you have a natural hybrid of a zucchini and a bumpy crookneck squash. Sometimes this happens. Always buy new seeds from a reputable seed source who isolates varieties to prevent accidental cross pollination. Don’t save your own seeds unless you control the pollination very carefully. Warty zucchini often have tougher skin but still taste okay.

  23. Tim says:

    Hello, for the second year in a row im getting all male and no female flowers. The females grow a few inches (the blossoms never even get close to opening) and then wither and die off. I know I don’t have full sun and only a few hours of direct sunlight a day…but otherwise the plants look dark green and healthy. What do you think my problems are? Not enough sun?

    • My guess would be not enough sun, but it may be a varietal issue too. Always grow 2 or 3 different varieties, if possible, to ensure at least some of them will be good fruiters.

  24. D Rodriguez says:

    Hello, I planted two zucchini plants two months ago in large containers in potting soil for flowers and vegetables. The plants have barely grown! They have lots of sun and I keep the soil moist, never had a problem growing zucchini before, any ideas?

    • Zucchini are notoriously tough to grow in containers. Make sure each plant has its own pot and the container holds at least 5 gallons of high-quality potting soil. Fertilize with a liquid organic fertilizer every two weeks.

  25. Thom says:

    My zucchini are like small football’s. 6″ long & 5″ wide. How come ?

    • Sounds like they might have been grown from seed that accidentally cross pollinated. This is why purchasing seed from reputable seed companies is key. Saving your own seeds is tough when it comes to members of the squash family because they cross-pollinate so readily.

  26. Nancy says:

    One of my zucchini plants is producing large eggplant shaped zucchini. They start out round and just get bigger, growing into giant oval shape. In the past I’ve had regular looking ones that if left get big, but this start out as round. In addition, when I cut into one I’ve picked the the inside does not seem ripe. What could be going on?

    • Sounds like they might have come from seed that accidentally cross pollinated with another variety in the farmer’s fields. Squash are very prone to cross pollinating and you don’t know it until you grow out the seeds. I’d recommend purchasing new seed next year from a reputable source. If you saved your own seeds, its likely your new plants are a natural hybrid.

  27. Cole says:

    I seem to have had the opposite problem; my squash grew ENORMOUS! The plant and the squash are out of control. I do have a beehive, so I guess that “helped” – will they normally just keep growing if I don’t pick them soon enough? And I’m not sure when is “soon enough”.

    • Squash grow very quickly so you have to pick them almost every day. I like my zucchini best when they’re about 8 to 10 inches long. But, if I’m making zucchini bread, I let them get much bigger than that. Just don’t let them get too big or they’ll be seedy and the skin will be tough.

  28. Cathy Sweeney says:

    I’m new at growing squash and have been successful so far as to growing from seed in a large container. My squash are still pretty young and I just noticed recently that there are a ton of little bugs flying and sitting on my squash when I move them. The squash is also starting to wilt. What is going on?

    • If you’re growing them in a container, the little flies could be fungus gnats which are just a nuisance, but won’t harm the plant. Their presence often means the potting soil is too wet. Make sure you aren’t leaving water sit in a saucer beneath the plant. Overwatering would also cause the plant to wilt.

  29. Briana says:

    Hi! I find your site to be very helpful, I planted one zucchini sapling (yellow) And it loves to push out a lot of zucchinis and leaves. Some of the zucchinis come out a deeper shade of yellow, and seem more hard than the lighter yellow which you might more commonly see you in the store, and seem to be more soft. I’m curious why some of my zucchinis might be growing a deeper shade of yellow and what this might mean. I have assessed For calcium and water deficiencies but I add ground up eggshells and water early on in the season and this has seemed to help with production. What could be the cause of a darker yellow zucchini?

    • This could be a varietal issue, or it could be due to the age of the fruits. Sometimes, as they mature, the fruits get darker and thicker skinned. This is especially true of yellow crook-neck squash.

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