A Complete Guide to Growing Zucchini 

More and more people are growing zucchini (Cucurbita pepo) in their gardens and it’s easy to see why. These attractive plants are surprisingly low maintenance and reliably produce large, great tasting yields.

A member of the Cucurbita family alongside cucumbers, melons and squashes, zucchini is technically a fruit. Also known as courgette, these plants are commonly grown alongside other summer or warm weather loving vegetables.

An ideal plant regardless of your situation, these prolific plants are monoecious. This means that instead of producing either male or female flowers, each plant produces both male and female flowers. Bees and pollinators visit the male flower and then the female flower, pollinating your plant.

Male flowers are long with thin stems and are usually larger than female flowers. The female flower has a small swelling at its base, the ovary. After pollination this swells into the fruit. Because the plants produce both male and female flowers you only need one zucchini plant to produce fruit. This makes it an ideal choice if space is at a premium. It is also easy to grow and harvest.

Easy to grow, zucchini are a staple of many peoples vegetable gardens. 

If you want to try growing zucchini in your garden this guide will take you through everything you need to know.

Different Varieties of Zucchini

Zucchini plants can either be grown from seed or purchased as young plants ready for transplanting into your garden. While the latter method is quicker, growing from seed is more affordable and offers you access to a wider range of varieties. Both seeds and plants can be purchased from garden stores and plant nurseries.

Some of the most popular varieties include:

• Eight Ball. This variety is grown for its nutty, buttery flavor. It produces dark green globe-like fruit that are ready for harvesting within 40 days of sowing.
• Seneca is prized for its dark green cylindrical fruit. The plant produces harvestable fruit within 42 days.
• Ambassador similarly produces dark green, cylindrical fruit. An early variety it can be harvested within 50 days of sowing.
• French White is a small bushy plant which produces white fruit. Ideal for smaller spaces, like Ambassador its fruit is harvestable within 50 days.
• Costata Romanesco is prized for its nutty flavor. Producing ribbed gray-green fruit which is decorated with pale green flecks, the fruit can be harvested within 52 days of germination.
• Spacemiser is a resilient, heavy yielding cultivar. Growing into an attractive bush, the green fruit can be harvested as baby squash within 45 days of sowing.
• Bossa Nova is a hybrid cultivar which produces fruit with a pleasant creamy flesh. A quick growing variety it can be harvested within 37 days of sowing.
• Lungo Bianco is a heirloom cultivar with a compact, bushy growth habit. Its attractive whilte fruits have a mild, sweet flavor and are ready to harvest within 70 days of sowing.
• Zucchini Golden is another heirloom bush variety that produces golden fruits which are ready to harvest within 55 days.

Courgettes come in a range of different shapes and colors. Take the time to select a variety that is best suited to growing in your garden. 

When selecting your plants, take the time to find a variety that is suitable for your growing conditions. If space is at a premium, plant dwarf or smaller cultivars such as Eight Ball. Similarly, these are heat loving plants so if you only enjoy a short summer plant fast maturing, early varieties such as Ambassador. This enables the plants to grow and bear fruit before the winter temperatures hit.

Where to Position Your Zucchini Plants

Growing zucchini plants love the sun. A full sun position, which receives 8 to 10 hours of sunlight everyday is ideal. While the plants can grow in positions that receive as little as 6 hours a day, growth may be slower and the yield not as bountiful.

A full sun loving crop, plant in rich, well draining soil. 

The soil should be light and well draining. Before planting or sowing prepare the soil by digging in about 4 inches of well composted organic matter. You can also work in 4 to 6 cups per 100 square feet of all purpose organic fertilizer. This helps to enrich the soil and is best done 3 to 4 weeks before planting.

Dense or heavy clay soils can be amended by working in compost or peat moss. This lightens the soil and improves drainage. Use a soil test kit to test the soil for nutrient deficiencies. The soil should be neutral to slightly acidic, a pH of 6.5 to 7.0 is perfect.

 

How to Sow Your Seeds

When sowing zucchini seeds remember that these plants like warm air and warm soil. Their optimal temperature is at least 70 ℉. Wait until the last frost date has passed and the soil is at least 60 ℉ before planting or sowing. Starting seeds in conditions cooler than their can stunt growth. To help warm the soil up cover it with a horticultural fleece or sheet of plastic.

Before sowing the seeds mound the soil up to create small hills, roughly 6 to 12 inches high and wide. This helps to improve drainage. Sow 3 to 5 seeds in a circle on top of the mound, about one inch deep and water well. Following germination this can be thinned out to just one seed.

You can also start seeds undercover and transplant outside when the temperatures have warmed sufficiently. Sow seeds undercover 4 to 6 weeks before your last predicted frost date.

If you are starting the seeds undercover, sow one seed per biodegradable pot roughly one inch deep. Seed Starter Peat Pots are ideal for starting vegetable and fruit seeds that will later be transferred into the garden.

Fill each pot with fresh, well draining potting soil. After sowing, cover the seeds and water well. Continue to keep the soil evenly moist during germination.

 

Wait until the soil has warmed before sowing your seeds. Following germination allow the seeds to develop at least one true set of leaves before thinning out. 

 

Transplanting Young Plants

When all chance of frost has passed begin hardening the seeds off and reduce watering. Allow the nighttime temperature around the seeds to fall to about 65 ℉.

Mound the soil up and plant one plant per mound, spacing them about 36 inches apart. Larger varieties may require more space, check the seed packet for precise spacing information.

If the seedlings have been started in biodegradable pots they can be planted still in their pots. Simply make a hole in the soil large enough to hold the pot and plant. The rim of the pot should sit level with the top of the soil. Gently firm down the soil and water well. As the plant grows the pot will break down, allowing roots to flourish.

Growing in Containers

Growing zucchini plants require lots of space.But this doesn’t mean that you can’t grow them in pots on a patio or balcony. Dwarf plants such as Eight Ball, Cue Ball and Gold Rush are all ideal for container gardens.

Your chosen pot should be at least 24 inches wide and 12 inches deep. The larger the better. As well as pots you can use any sort of container, such as a barrel, as long as it has drainage holes at the bottom.

Fill your chosen container with a light, well draining potting soil. You can further lighten the soil by working in perlite or vermiculite. Sow the seeds as described above around two weeks after the last frost.

Plant around three seeds in the center of the container about an inch deep. Space the seeds a few inches apart. After planting lightly water the soil, try to keep it moist until the seeds germinate in a couple of weeks. Following germination pick out the weakest seedlings, leaving only one plant to grow on.

Caring for Growing Zucchini Plants

Following germination once seedlings are established, apply a layer of mulch around the plants. This helps the soil to retain moisture and keep an even temperature. This can help the plants to produce larger, earlier crops.

Mulching also helps to deter weeds. Aim to keep the soil as weed free as possible. When weeding try not to damage the root system of the plant. 

Mulching the soil helps to prevent weed growth. It can also be used to elevate fruit, helping to prevent it from rotting in wet conditions. 

When to Water

Growing zucchini plants need at least 2 inches of water a week. Try to water the soil not the foliage, zucchini is prone to developing powdery mildew especially if the foliage is allowed to remain damp.

Plants in containers require more frequent watering than those in the ground or raised beds. If you are growing in containers wait until the top two inches of soil are dry to the touch before watering deeply. Allow the top soil to dry before watering again.

A soil moisture gauge, such as the Atree Soil Moisture Meter, can be useful if you struggle to know when to water your plants.

Fertilizing Growing Plants

These are quick growing, prolific plants. Consequently zucchini requires regular fertilizing to sustain its rapid growth habit.

If you have enriched the soil before planting, when seedlings emerge apply a light dose of general purpose fertilizer. Repeat this when blossoms form. Organic solutions such as diluted fish emulsion can also be used. When fertilizing your plants, make sure that you properly water in the fertilizer so that it soaks all the way down to the root system.

If you haven’t enriched the soil before planting, apply a balanced fertilizer once every four weeks. This may also need to be done if you are growing in containers. Water soluble or liquid fertilizers are easily incorporated into the watering routine. Alternatively you can add a slow release fertilizer when you sow or plant.

Fertilize once seedlings emerge and again when blossoms set. This helps the plant to sustain its prolific growth habit. 

 

Supporting Growing Zucchini Plants

Larger plants require staking. A trellis or tomato cage is an ideal way to support the vines. This should be installed at the time of planting or sowing to prevent accidental damage to the root system. Dwarf and container varieties rarely require staking.

Sometimes your growing zucchini plants can become floppy. Mound the soil up to support the base of the plant. Floppy plants may simply require more water.

Frost Protection

Zucchini is a warm weather plant, even a light frost can cause damage and injury. Protect plants from late or early frosts with a horticultural fleece.

You can also cover the lower part of the plant and soil above the root system with straw, newspapers, old sheets or plastic. The aim of covering the soil in this way is to trap the heat in the soil and keep the plant warm. This only works on light forests. Heavier frosts may still damage and kill the plants. If a heavy frost does strike, harvest the fruit immediately.

Pruning your Plants

The large foliage of the growing zucchini plant can prevent the fruit from receiving enough sunlight. It can also overcrowd a space, blocking other plants from growing.

Pruning helps to keep the plants in check. It can also help to stimulate additional growth. Finally, even a light pruning can improve the air circulation around the plants. This helps to prevent issues such as powdery mildew.

Source: https://www.youtube.com/watch?v=mqkpifoEUfc 

Once the plants have begun to set fruit, usually 4 to 6 on each vine, you can start to prune. Begin by pinching out or cutting away the tips.

Continue to cut away excess foliage as and when needed during the growing season. Be careful not to cut too close to the developing fruit.

When pruning, don’t remove all the foliage. Keep some foliage on the stem including leaf nodes near the last fruit on the vine that you want to keep. Cut away larger leaves.

You can also cut away brown or dying foliage. When pruning try not to cut the stems, this can encourage disease.

Companion Planting

Growing zucchini plants can benefit from companion planting. This is the practice of growing mutually beneficial plants in close proximity to each other.

Radishes make good zucchini and summer squash companions because they repel common pests such as cucumber beetles, squash bugs and aphids. They are particularly effective if you allow them to flower and go to seed. Garlic also helps to keep pests such as aphids away.

Legumes such as green beans and peas make for ideal companions because they help to fix nitrogen in the soil, providing growing zucchini plants with a nutrient boost.

Nasturtiums are good trap plants, attracting aphids and flea beetles away from your plants. Marigolds are believed to emit an aroma that discourages pests such as nematodes. Both flowers, like zinnias, also attract pollinators such as bees, these are useful for increasing your harvest. Borage can also be used to attract pollinators.

Plant herbs such as peppermint, oregano, dill, mint, marjoram and catnip to keep pests away.

Encouraging pollinators to your garden helps to increase plant yields. After pollination the base or ovary of the female flower swells, growing into a zucchini fruit. 

Avoid planting potatoes near growing zucchini. Potatoes seem to have a negative effect on a number of plants. Also avoid growing close to pumpkins to prevent cross pollination.

 

Problems Commonly Encountered when Growing Zucchini

Growing zucchini is a pleasingly easy, problem free process. However there are a few things to watch out for.

Regularly check your plants for signs of infestation from:

• Aphids
• Cucumber beetles
• Cutworms
• Spider mites
• Squash bugs
• Vine borers
• Whiteflies

If spotted early enough infestations can be treated with an application of insecticidal soap. An effective, organic solution, it is easy to make insecticidal soap at home.

You may also need to protect the fruit from birds, squirrels and other large pests. Garden Bird Netting or row covers is ideal.

Regularly check the dense foliage of your plants for signs of infestation.

Growing zucchini plants are also susceptible to a number of diseases such as powdery and downy mildew. Bacterial wilt and botrytis blight can also be issues.

Treating these diseases can be difficult, they often prove fatal. Instead try to prevent the issues from occurring in the first place by adopting good growing practices such as correctly spacing out the plants and keeping the foliage as dry as possible when watering.

Blossom drop can be seen to be a problem. However, it is normal for growing zucchini plants to lose some flowers and is considered a natural part of the growing process.

Hollow fruits are more common early in the season and can be a sign of poor pollination. This may be caused by wet weather discouraging pollinators or overly hot and dry conditions, causing the pollen to dry out before pollination can occur. If this affects your plants try raising the humidity levels around the plant and hand pollinating. Hollow fruit can also be a sign of an irregular watering routine.

Bumps on the fruit are either a sign of an incurable virus, such as cucumber mosaic virus, or too much calcium in the soil.

Fruit falling from the plant before it is fully grown is a sign of poor or no pollination. Try attracting pollinators to your garden. It can also be a sign of blossom end rot.

Blossom End Rot

Blossom end rot first appears as a small bruise at the blossom end of the fruit. As it develops the fruit gradually darkens and softens, eventually rotting completely.

Blossom end rot is commonly caused by a calcium deficiency in the soil. Heavy bearing plants, such as zucchini, are more likely to suffer from this issue because calcium is a key ingredient in promoting healthy growth. Test your soil before planting to ensure calcium levels are high enough. Also be careful when weeding not to damage the roots. This can stress the plants and cause blossom end rot to develop.

If spotted early enough blossom end rot can be treated by adding calcium to the soil. Calcium carbonate tablets, or antacid tablets can be inserted into the soil at the base of the plant. As the tablet dissolves the plant absorbs the nutrients getting an instant calcium boost.

How to Deal with Yellowing Foliage

Yellowing foliage, chlorosis, can be caused by a number of things. One of the most common causes of yellow foliage is spider mites. These little pests suck the sap from the foliage causing it to yellow.

Cucumber mosaic virus, transmitted by aphids, is another common cause of yellowing foliage. It can also stunt growth and prevent fruit from forming properly. Cut away and destroy affected sections to prevent the virus from spreading to the rest of the plants.

Remember, preventing problems is easier than curing them so regularly check your plants for signs of infestation.

Fusarium wilt, a fungal disease, can also cause foliage to yellow. Once infected there is no cure, simply dig up and destroy the plant. Planting in a rich soil that is well draining helps to prevent yellowing foliage and keeps plants healthy.

Iron, manganese and sulfur deficiencies in the soil can also cause foliage to yellow.

How to Harvest Your Fruit

Zucchini fruit emerges between the plant’s large leaves. It can be difficult to know where your fruit is so regularly check the plant. Don’t allow your fruit to become too large, otherwise it may become stringy and tough.

Usually zucchini squash is ready for harvesting when it is 6 to 8 inches long. These are more tender and flavorsome than larger, harder fruit. While the fruit can grow up to 1 ft in length, it is often best picked small.

Harvest when the fruits are firm and glossy. Mushy or soft fruit is probably rotting and should be discarded.

The color can also indicate when the fruit is ready to harvest. The fruit of most varieties ripens to a dark green in color. Some cultivars produce yellow or white fruit.

Source: https://www.youtube.com/watch?v=wBVw-rQEDSY 

When harvesting, don’t just pull the fruit from the plant. This can damage the vines. Instead cut it from the stem. Be careful when looking through the foliage for fruit not to damage the delicate foliage and stems.

Picking regularly can encourage more fruit to form. If you find yourself with too much zucchini fruit, try allowing a few to remain on the plant. This slows down fruit production.

 

Storing your Fruit

Unwashed fruits can be stored in open or perforated plastic bags for up to a week. They can also be frozen for longer term storage.

To freeze the fruit, shred an unpeeled zucchini and drain it in a colander, squeezing away the excess moisture. Place the zucchini in a freezer bag and freeze it flat, so that it can be stacked. Alternatively, wash and dry the fruit before cutting it into cubes and freezing the cubs in bags.

Frozen fruit lasts for around 3 months.

Saving the Seeds for Future Planting

You can only save seeds from open-pollinated or non hybrid varieties such as heirloom plants. Seeds saved from hybrid plants are unlikely to produce fruit. If the plant does bear fruit it is likely to be small and lacking in flavor.

Harvest seeds from fully mature fruit. Allow the fruit to over ripen on the vine for as long as possible. This helps to ensure that the seeds are fully developed.

After harvesting, cut open your over ripe fruit and scoop out the creamy white seeds. Remove as much pulp as possible before placing the seeds in a bowl of water. Viable seeds float to the surface. These can be removed and dried. Dispose of the dead seeds.

Thoroughly dry out the seeds before storing or sowing. This is easily done by spreading the seeds flat out on a tray and placing them in a dry, humid free place for a few days.

As they dry the seeds harden up and shrink slightly. Once they are fully dry place the seeds in an airtight jar until you are read to use them. Remember to label and date your jar, the older they are the less viable seeds become.

Growing zucchini is a pleasingly straightforward, problem free process. This easy going nature helps to make it one of the more enjoyable plants to grow in your vegetable garden.

Easy to plant and care for, growing zucchini is a great way to get into growing vegetables. Its heavy yielding nature makes this one of the most rewarding plants to grow.