Zucchini is well-known for being a garden crop of overabundance. Growing massive amounts of healthy fruits is absolutely possible, but it does take the right conditions and proper growing techniques. There are some common zucchini-growing mistakes that you can make which would create either a minor setback or could cause your entire crop to fail.
Zucchini (Cucurbita pepo), also known as courgette, is a variety of summer squash. It is a warm-season crop typically harvested at the peak of summer. When picked in an immature phase, the entire fruit is edible, including the seeds and the skin.
This popular garden fruit is an easy-to-grow annual that matures quickly, so you can generally harvest zucchinis within 60 days of sowing seeds and even sooner for greenhouse-grown transplants.
With a couple of warm months in the summer, a sunny garden plot, and rich, moist soil, you can probably grow summer squash. You certainly don’t need a green thumb or be an experienced gardener to have some success with these prolific plants. If you’re feeling adventurous, there are many interesting varieties and cultivars to try.
Keep reading to learn how to avoid these 15 common mistakes and improve your zucchini-growing success!
Improper Seed Sowing
Use fresh seeds, store them in a cool, dark place, and start seeds shallow in the soil.
First, if you are growing zucchini from seed, use fresh seeds. Squash seeds can stay viable for up to four years, although their germination rates will drop as they age.
At some point, old seeds simply won’t grow at all. Store your seeds in a cool, dark, dry location. Any seeds that are soft, mushy, or moldy should be discarded.
Zucchini seeds can be planted in small pots or directly sown in the garden. Sow seeds 1/2 inch to 1 inch deep in fresh garden soil. Seeds sown too deep won’t sprout or grow well, and seeds sown too shallowly are prone to drying out and being eaten by birds and rodents.
If you start your plants inside, always harden off the seedlings before transplanting them into your garden. During the daytime, place the seedlings outdoors in a somewhat protected location to help them adjust to the more harsh outdoor environment. Allow them some outside time every day for a week or so before transplanting them into your garden. This will help your plants thrive after transplanting and reduces transplant shock.
Starting Too Early
Wait until after your last frost date to start zucchini seeds, as they need warm temperatures, and delay helps avoid pests.
Zucchini has a relatively short growing season and takes only about 45 to 60 days from seed to harvest. The seeds germinate in about 7 to 14 days after sowing. They will then be ready to transplant in as little as 2 to 4 weeks after sowing.
After a long winter wait, you may be anxious to return to the garden and start your plants as early as possible. But don’t start them too early. Wait at least 3 weeks, or even more, after the last frost date to transplant seedlings or start your seeds outdoors.
You may encounter a few problems if you start your seeds too early in the growing season, indoors or outdoors. Cucurbit plants are very cold-sensitive. The soil should be at least 60°F, and the nighttime temperatures should stay above 40°F. A late frost can quickly wipe out your plants.
When zucchini transplants (or any cucurbit) are started too soon, they can become rootbound while waiting for warm weather, causing severe transplant shock. Squash grows quickly, so don’t start seeds indoors until 1-2 weeks before you plan to transplant.
Another big benefit of starting seeds later is that delaying your plantings can help you avoid some early-season insect pests. Squash vine borer moths, in particular, are most active in early spring. Delaying your planting may help keep your plants from being heavily infested with borers.
Not Enough Sun
Squash needs 6-8 hours of sun for best growth and fruit production.
Zucchini and other summer squash need at least 6 to 8 hours of direct sunlight each day. These plants can easily handle a full day’s worth of sunlight which will help them thrive and produce the best fruits. Plants grown in a shaded area will grow leggy and weak and won’t flower well, nor will they attract as many pollinators in the shade.
You’ll want to place your squash in an open location. Avoid planting them in the shade of a building or wall. Don’t plant them at the edge of a wooded area where trees and shrubs will shade them. If you plant zucchini plants too close to each other, they will also compete for sunlight. Similarly, be aware that these plants can grow quite large and shade out other nearby plants.
Not Enough Water
Keep zucchini moist but not soggy, with 1-2 inches of water per week.
Zucchini likes to be kept moist, but soil should not be soggy wet. Zucchini needs about 1 to 2 inches of water each week. Be especially aware during the hottest and driest summer days, and ensure your plants get enough water. On the hottest days, your plants will probably wilt during the midday heat, even if they are well-watered, so wilting by itself may not be a sign that your plant needs water.
If you grow in a raised bed, live in an arid climate, or have sandy soil, you will likely need to water them a bit extra. Check the soil with your finger, including several inches below the surface, to be sure the water reaches the plant roots. Fruits grown on water-deprived plants won’t be high-quality.
Improper Watering
Deep watering 1-2 times per week is better than frequent shallow watering.
When adding supplemental watering, there are a few things to be aware of. Don’t spray water directly on the leaves. This common zucchini-growing mistake can lead to an increased likelihood of fungal infections, particularly powdery mildew.
When it rains, the rain will get the leaves wet, and that’s fine, but when you water by hand, you can take precautions to avoid unnecessary water on the leaves. Instead, use a hand-held watering wand or a soaker hose to keep the water low and at the roots where it’s most needed.
Another watering technique to use is to water deeply rather than shallowly. One or two deep waterings each week is better than 3 or 4 shallow waterings each week. If only the soil surface gets wet, the water isn’t soaking in deep enough to penetrate to the roots where it’s most needed. Take extra time with watering to be sure your plants get enough.
Poor Soil Quality
Enrich the soil with compost or amendments for a well-drained, nutrient-rich bed before planting.
Squash is a heavy feeder; its voracious appetite for nutrients means it needs rich soil. Add compost to your garden bed at planting time to give your plants a head start. If you have a compost bin and produce your own compost, this would be an excellent opportunity to use it. You can also buy organic compost commercially. You’ll want to blend this into your existing soil to improve the soil’s nutrient density and tilth.
Overall, the soil quality for zucchini plants should be rich, moist, and well-drained. Is your soil well-drained, or is it heavy clay? Is your soil sandy, gravelly, or already rich with organic matter? Work some compost or soil amendments into your soil to enrich its quality. Do some soil preparation before planting your zucchini in your garden bed to give it the best soil possible.
Not Fertilizing
Nourish zucchini with rich soil at planting and add fertilizer when flowering for fruit production.
Plants need the energy to grow and even more energy to produce fruits. When you first plant your zucchini, give it nutrient-rich soil with plenty of organic matter. Ideally, this will be a hefty dose of organic compost that has been thoroughly worked in.
When your zucchini starts to flower and produce fruits, it’s time to add some extra fertilizer. You can use an all-purpose gardening fertilizer and follow the directions on the label. You can also add a side-dressing of more organic compost and work this into the soil around your plant.
Fertilizer is important when growing squash.
Lack of Pollination
For squash to fruit, it relies on pollinators, but you can hand-pollinate by transferring pollen from male to female flowers.
Squash has both male and female flowers and relies on pollinators to produce fruits. In brief, a pollinated female flower will form a fruit, and an unpollinated female flower will not.
In a typical healthy garden with a diversity of plants, you will have plenty of pollinators flying around, and your zucchini flowers will be pollinated naturally. You can attract pollinators by growing pollinator-friendly plants nearby, such as zinnias, coneflowers, and lavender.
If you notice that you have both male and female plants and the female fruits never start to develop and get larger, you may have a lack of pollinators.
Fortunately, it is very easy to hand-pollinate these flowers. Simply take a mature male flower (the ones with no immature fruit attached to the base of its stem) and rub the pollen-covered anthers across the inside of a female flower (the ones with an immature fruit at the base of the flowering stem).
Harvesting Too Late
Harvest zucchini at 6 inches for tender, juicy fruit.
If you want the most tender, perfect zucchini fruits, pick them when they’re about 6 inches long. Younger, smaller zucchini fruits will be firm yet tender; the seeds will be very small, soft, and full of moisture. Overripe squash will develop a more dry, spongy, or mealy texture. The seeds of older fruits will be large and tough, and the skin can also become tough and unappetizing.
It’s surprisingly easy to miss a harvest opportunity with zucchini. The plants grow fast, and the fruits grow very fast and mature quickly. You could easily miss the perfect zucchini if you don’t check your plants 2-5 times per week while fruiting.
I often check them every day. If you miss out on picking a young zucchini and end up with an unappetizing giant fruit, don’t worry! Harvest it and toss it in your compost or feed it to your chickens.
Feeding the Bugs
Delay zucchini planting to thwart squash vine borers and squash bugs, which are active earlier in the season.
A couple of insect pests can quickly decimate your zucchini crop. Squash vine borers burrow into the stems. Plant your squash a little later to avoid the most active season of these persistent pests. Squash bugs are another major pest of zucchini plants. Planting a bit later in the season can also help protect against these pests because they are most active earlier in the spring.
Before plants flower, you can also protect them with floating row covers. However, once they begin to flower, you’ll need to remove any protective covers to allow pollinator access to the flowers.
Ignoring Problems
Combat pests and diseases in zucchini by controlling pests and growing disease-resistant varieties.
There are plenty of pests and diseases that attack summer squash. Don’t ignore them. Powdery mildew, for example, is a major problem, and zucchini is highly susceptible. A minor infestation may eventually cause your plants to turn yellow and die, and there may not be much you can do about it. Accept it, harvest your zucchini early, and perhaps plant another crop.
If you have an infestation of insects, however, there are some actions you can take. Hand-pick as many as you can, including adults, nymphs, larvae, and eggs. Try spraying a jet of water spray at the leaf insects you see. This will dislodge them and make it harder for them to feed on plant juices.
Try growing disease-resistant varieties to give your plants extra protection from problems. You can find zucchini plants with built-in resistance to powdery mildew, downy mildew, and even some viruses.
These disease-resistant plants aren’t totally foolproof, but if you have battled severe cases of mildew in the past, consider growing a mildew-resistant variety of squash. ‘Emerald Delight‘ is a lovely selection from Botanical Interests.
Wrong Companion Plants
Companion plants like corn, beans, nasturtiums, marigolds, and sunflowers help repel pests and attract pollinators.
There are plenty of plants that you can grow near your zucchini to help repel insect pests and attract pollinators. Some good companion plants that offer some benefits to zucchini include corn, beans, nasturtiums, marigolds, and sunflowers. Nasturtium is considered a great vegetable garden companion plant because they are easy to grow, attracts pollinators, and repels pests.
So what shouldn’t you plant nearby? Don’t plant zucchini next to plants in the Brassica family, which includes broccoli, Brussels sprouts, and kale.
Why not? Like zucchini, these plants are heavy feeders and compete for soil nutrients. They also attract many insect pests, which can transfer to your zucchini plants. Similarly, don’t plant potatoes near your zucchini. They will compete for space and attract the same pests.
Not Mulching
Mulch zucchini with organic compost like leaf mulch or straw for consistent soil moisture and weed control.
You don’t have to mulch your zucchini, but mulching can help your plants grow. Organic composts, such as leaf mulch or clean straw mulch, make excellent mulch. Natural mulches can help enrich the soil and have other benefits as well.
Mulching can help keep the soil temperature consistent. Mulch will help keep the soil moist, and zucchini really appreciate constant soil moisture. Finally, mulching around your plants can also help control weeds. It won’t eliminate weeds entirely, but it will help.
Not Allowing Enough Space
Summer squash plants need ample space due to their large size.
Zucchini plants are space hogs. They have broad leaves and long stems growing in a mounded, slightly trailing rosette. These plants are large and robust and can grow several feet across.
You can plant them individually or in small groups sharing a raised mound or hill. Space your individual plants at least 36 inches apart. If you want to try growing them in hills, you can grow 2 or 3 plants, spaced about 24 inches apart, in a broad raised mound of earth. You should still plan to allow at least 36 inches between mounds.
Not Weeding
Don’t let weeds take over. Hand-pull or use mulch to control them.
It’s hot outside, and who wants to spend time out there pulling weeds? If you don’t pull the weeds, they’ll take over. No garden plant likes weedy competition, especially zucchini.
You can use mulch to help control weeds, but you will still have to do some weeding. Hand-pull weeds close to the base of the plant, but if you have a bunch of bare space around the plants, especially when your plants are small, you can use a hand cultivator or a small hoe to dislodge and remove the weeds in the surrounding area.
Final Thoughts
Zucchini is a much-loved plant in the summer garden. It grows fast and large, and can produce abundant fruits. It has simple basic needs: rich, moist, well-drained soil and full sun. But plenty of obstacles can get in the way between you and the perfect zucchini. Once you understand how best to grow and manage your zucchini crop, you will be well along your way to growing your super-abundance of summer squash!
