How to Grow Zucchini: Your Guide to Growing this Summer Squash

Learning how to grow zucchini is pretty straightforward. In fact these were one of the first plants I grew when I first had a vegetable garden, so they can definitely be a good crop for beginner gardeners.

Zucchini, also known as courgette, is a summer squash of the Cucurbitaceae family. The Latin name is cucurbita pepo. They are the immature fruit of what are known in the UK as Marrow. The plant originates from Central America but was first cultivated in Italy.

Summary of key facts about growing zucchini

Here is a quick run down of the key points about how to grow zucchini:

• Zucchini can be prolific plants if grown in the right conditions and a well cared for plant can produce up to 20 fruit in a season. This means you’ll typically only need 3 or 4 zucchini plants in most home gardens.
• Zucchini are these days bred for their thin skins and mild, sweet taste. They are usually green but can also be yellow or white. The fruit typically measures between 15 to 30 cm (6 and 12 inches) long and 5 to 8cm (2 to 3 inches) in diameter with smooth, shiny skin.
• Under ideal conditions, zucchini will grow rapidly and produce an abundant crop within 50 to 60 days of sowing seeds or planting out transplants.
• When choosing a location to plant zucchini, make sure it is in full sun and has well-drained soil, rich in organic matter such as composted leaves or manure.
• Zucchini require little maintenance once established; however, regular watering is necessary to keep the plants healthy and producing fruits.
• If growing zucchini in containers, fertilise every two weeks using a balanced fertiliser such as a liquid seaweed mix.
• Harvest zucchini when they are 6-8 inches long for best flavour and texture.
• To harvest, cut the fruit from the plant with a sharp knife or secateurs. Avoid bruising or damaging the fruits as they can rot quickly after being harvested.
• Store zucchini in a cool, dry place out of direct sunlight. Use within 2-3 days for best quality.
• Zucchini is a versatile vegetable that can be used in many different recipes such as soups, salads, main dishes, and even desserts. When cooking with zucchini, remember to not overcook it as this will cause it to become mushy and lose its flavour.

How to grow zucchini from seed

Sowing zucchini seed indoors

if you’re thinking about growing zucchini in your garden, here’s what you need to know about sowing the seed.

Zucchini need soil temperatures of at least 13 to 15°C (56-60°F) to germinate. They are fast growing once temperatures warm up but they are easily checked or damaged by cold temperatures. So, there is not point trying to sow zucchini seeds too early.

You can start you zucchini seeds off indoors or under heated glass around a month before you expect the last frost to happen.

Zucchini do not transplant particularly well. So, sow them in individual pots or modules that are around 7cm (3 inches) across, rather than in trays.

Fill the pots with potting compost and sow the seeds around 2.5cm (1 inch) deep. To guard against erratic germination, you can sow two or three seeds to the pot, removing the weakest plants after germination to leave one plant to grow on.

Place the pots or module trays in a warm location and keep them moist (but don’t over-water) until the seeds germinate. Once the seedlings have come up, keep them in good light, otherwise they become leggy and elongated and grow into weaker plants.

When the risk of frost has disappeared and your plants have at least two strong leaves and signs of a third leaf developing, you can transplant them outdoors. Make sure you harden them off for a week or so before planting outside.

This means placing them outside in a sheltered spot during the day and then bringing them back under cover at night. After a few days you can leave them outside in the sheltered spot overnight as well, before planting then out in your chosen spot.

Sowing zucchini seed outdoors

Zucchini seeds can be sown directly into the ground rather than being transplanted in from a pot or module – this will help reduce transplant shock and encourage strong root growth.

However, to sow zucchini seed outdoors, you must wait until the frosts are over and the soil has warmed up to 13 -15°C (55-59° F).

To sow zucchini seeds direct, make a small hole in the ground with your finger or a dibber and drop one or two seeds into the hole and then cover it over with soil. Water well and keep an eye on the area – when the seedlings come through, thin them out so that only one plant remains per location.

Good advice from the Royal Horticultural Society is to cover your seedlings with a cloche or jar for a week or two after germination to given them added protection from the weather and potential attackers, like slugs and snails.

Zucchinis are ready to harvest around 50-60 days after planting. Whether you start your zucchini plants indoors or outdoors, be sure to give them plenty of water and feed them them regularly with liquid seaweed, or other balanced fertiliser for best results.

Zucchini Planting Guide

When to plant zucchini

As indicated, zucchinis should be planted in late spring/early summer. In most parts of the US and the UK, that means May or June.

However, it is important to check your local frost dates before planting – you don’t want to put your plants in too early and risk them being damaged by frost.

How much sun do zucchini need?

Zucchini need lots of sunshine – ideally 8 hours per day – but they will tolerate some shade. In very hot climates they will benefit from afternoon shade if possible, as this helps prevent their leaves from getting scorched by the hot afternoon sun.

How far apart should zucchini be spaced?

Each zucchini plant needs around 2-3 feet (60-90cm) of space all around it. So when planning where you’re going to put your plants, make sure there is enough room between each one.

What kind soil do zucchini need?

Zucchini can be large plants and grow quickly, so they need plenty of soil nutrients.

Hence, zucchini need fertile, moisture retentive, humus rich soil with good drainage. In wet areas, sow or plant your zucchini into mounds so that the roots don’t get waterlogged.

To achieve the soil conditions required, dig in plenty of well rotted manure and/or garden compost to the soil before the growing season. Pelleted chicken manure will also work well.

How to grow zucchini in pots and containers

Zucchini can easily be grown in pots or containers, but because they become quite large plants, you need to make sure your container is large enough – at least 18 inches (45cm) wide is best.

You can even grow zucchini in grow-bags or in any suitable reused container, like a 5 gallon bucket, as long as it has been throughly cleaned and drainage holes have been punched through the bottom of it.

Except for in very large planters, stick to one plant per container. If using a grow-bag you can grow 2 plants per bag.

As with all container growing, you need to be aware that the nutrients in the potting compost will be exhausted after 3-4 weeks. This means it is critical to feed zucchini growing in pots on a regular basis with a balanced liquid fertiliser. As noted below, a high potassium feed should be used once the plant starts fruiting.

Remember, also that compost in pots dries out very easily in hot conditions, so make sure you have a regular, thorough watering regime.

How to grow zucchini vertically

Zucchini are not technically climbing plants, but they can be sprawling plants. This sprawling tendency, on some varieties at least, means that you can tie zucchini into a vertical support as they grow.

You can use a single support like a strong bamboo cane or tree stake, or you can use a framework, like a fence or trellis to tie the zucchini into.

I have used a strong bamboo cane in the past, and it works perfectly well. But you do need to make sure it is banged deeply into the soil when you start. Zucchini are vigorous plants and can become heavy. So, if the support is not stable, it can easily topple over.

Once you have your support in place, sow you seeds or plant out your seedling on the sunny side of the support. As the plant begins to grow, lift it up and tie in the stem to the support. Keep tying in every for 10 to 15cm (4 to 6 inches) as the plant continues to grow.

‘Raven,’ ‘Thunderbird’, ‘Costata Romanesco’, ‘Black Forest’, Tomboncino and ‘Partenon’ are vining zucchini varieties that be suitable for growing vertically.

Watering and fertilising zucchini

Here are some tips on how to properly water and fertilise your zucchini plants for optimal growth.

Watering

Too much or too little water can lead to problems with any plant, so it’s important to get it right. The best time to water is in the morning, giving the plant a chance to dry out during the day.

Zucchini do need to be watered regularly as they grow in to large plants quite quickly. If your soil is rich and fertile, as described above, you shouldn’t need to water your zucchini too much.

However, on lighter, free-draining soils extra more watering may be necessary. If the plants develop a strange blotchy look, that is a sign that they need more water.

Fertilising

Again, if your soil is good then very little extra fertiliser will be needed, although a boost with pelleted chicken manure, or the like, will not do any harm a few weeks after planting out. On lighter soils, a feed once a month with liquid seaweed or compost or manure tea will give your zucchini plants the nutrients they need to grow on well.

Once the fruit start appearing it is advisable to feed the plants every two weeks with a high potassium feed – a liquid tomato feed will do the job – because potassium encourages the growth of flowers and fruit.

Zucchini pests and diseases

Pests and diseases can be a big problem for gardeners, especially when it comes to zucchinis. These plants are susceptible to a number of different pests and diseases, which can affect how well they’ll grow.

Pests

One of the most common pests that affects zucchini plants is the cucumber beetle. This beetle attacks the leaves of the zucchini plant,  causing them to yellow and eventually die. The best way to control cucumber beetles is by staying vigilant, picking off beetles by hand when you see them.

Another common pest in North America is the squash bug, which sucks the sap out of the plant’s stems and leaves. Squash bugs can be controlled by hand-picking them off of plants (if you’re brave enough). One of the problems with squash bugs is that they is carry cucurbit yellow vine disease bacterium. They can also give off a really unpleasant odour when disturbed.

Aphids can also be a problem, especially in relation to young plants. To help combat aphids, you can encourage natural aphid predators like ladybirds (ladybugs) and hover-flies, by leaving perennial flower stalks in place for them to overwinter in. You can also squash the aphids between your fingers when they start becoming a problem or use a hose to blast them off the plant.

Finally, and this is the biggest pest problem I usually have, slugs and snails, will often nibble the young fruit, especially those nearest the ground. You can combat them with (organic) slug pellets, or with eggshells or sharp grit sprinkled around the plant, which they will be reluctant to slither across.

Diseases

Diseases also pose a threat to zucchini plants.

The one disease that, in my experience, very commonly affects these plants is powdery mildew.

This fungal disease appears as white powdery spots on leaves and stems; it usually occurs when conditions are humid at night or when plants have become too dry. You can try to prevent it occurring by watering only at ground level so that foliage stays dry. Avoid overhead watering if possible.

In my opinion, there is no very satisfactory cure for powdery mildew, but you can try treating it with an appropriate fungicide containing potassium bicarbonate, neem oil, sulphur, or copper. Also, pick off and destroy affected leaves.

Other diseases that may affect zucchinis include bacterial wilt, downy mildew, and mosaic virus.

Some of these diseases can be prevented by planting disease resistant varieties. Otherwise, assuming you don’t want to spray chemicals on your food, the best advice to gardeners is to keep a watchful eye on your zucchini plants throughout the growing season in order detect any potential problems early on.

By doing this, they will have a better chance of preventing serious damage – ultimately resulting in healthier harvests.

Key Takeaway: Pests and diseases can be a problem for gardeners growing zucchinis. Hand removal can help control cucumber beetles and squash bugs. Powdery mildew can be prevented by watering only at ground level. Other diseases may be prevented by planting resistant varieties.

Harvesting your freshly grown zucchini

Harvesting your zucchini can be a rewarding experience, especially if you’ve grown them yourself!

Here are some tips on when and how to harvest your zucchini crop:

1. Timing Is Everything

The simple advice is to wait until the zucchini is around 15cm (6 inches) long, has a deep green colour, and is firm to the touch.

For the sweetest tasting zucchini, pick when the fruit are small and the flower is still intact on the end of the fruit. Zucchini left long can lack taste and have harder texture.

Also, harvest frequently, as this will encourage more flowering and more fruit.

2. Cut carefully

Cut the zucchini Squash from the plant using a sharp knife or secateurs. I use my trusty Felco secateurs. Cut on the stem above the fruit, to avoid damage to the fruit, as any damage will affect its storing capacity.

Be careful also not to damage the plant in the process.

3 Tools that will make harvesting easier

1. A sharp knife or garden secateurs – as mentioned above, these will help you cleanly cut the zucchini stem without damaging either it or the plant itself.
2. A large bowl or bucket – this will serve as a makeshift “harvest basket” to collect all of your lovely fruit in one place.
3. Gloves (optional) – zucchini plants can be a bit spiky. Gloves can provide an extra layer of protection.

Key Takeaway: Timing is everything when harvesting zucchini – wait until they’re 6-8 inches long and deep green in colour.

FAQs in relation growing zucchini

What is the best way to grow zucchini?

As noted above, there are a few things to keep in mind for the best results when growing zucchini. Zucchini need full sun and well-drained fertile soil with a lot of organic matter.

They also require consistent moisture, especially when they are flowering and fruiting. To avoid disease problems, do not plant zucchini where other members of the cucurbit family have been grown recently.

When planting, put them about 2 to 3 feet apart in rows that are at least 3 feet feet apart. Mulch around plants to help retain moisture and control weeds.

Be sure to water at the base of plants rather than wetting leaves so that foliage does not stay wet for long periods of time which can lead to fungal diseases. Harvest fruits regularly when they are small (6-8 inches) for the best flavour.

Do zucchini need to climb?

No, zucchini do not need to climb but, as noted above, some varieties will. Zucchini is a type of squash that belongs to the cucurbitaceae family, which includes other squashes like pumpkins and cucumbers.

This vegetable is typically grown on the ground in gardens or raised beds. While some gardeners may train their zucchini plants to grow vertically on fences or trellises, this isn’t necessary for the plant’s health or yield.

Zucchini plants will typically produce just as much fruit whether they are allowed to sprawl on the ground or climb upwards.

Pollination – do zucchini need two plants to get fruit?

No, zucchini only need one plant to produce fruit. Zucchini are monoecious, meaning that each individual plant contains both male and female reproductive organs.

In Zucchini and other cucurbits (like cucumber), we see this in the quite different male and female flowers that develop on each plant.

The male flowers appear on longish, thin stems as in the example in the picture on the right below. The female flowers sit above an immature fruit (see example on the left below) that will develop if pollination occurs.

The flowers of the zucchini plant are pollinated by bees or other insects, who transfer pollen from the stamen (the male organ) on the male flower to the pistil (the female organ) on the female flower. Once pollination occurs, the immature fruit beneath the female flower will begin to swell and grow.

You can even hand pollinate your plants yourself if pollinating insects are not doing the job, which may happen early on the season or in cold weather. Here is how:

• Cut a fully open male flower off the plant and strip off all its petals;
• Push the the male flower into the centre of the female flower, trying to ensure pollen is transferred on to the stigma, which is the sticky pad at the top of the pistil.
• Use the male flower to fertilise other female flowers as long as there is some remaining pollen.

How long does it take zucchini to grow?

Zucchini is a fast-growing plant that can produce fruit in as little as 40 days. However, most varieties will take between 50 and 60 days to mature.

Make sure you follow the instructions above regarding feeding and watering, especially if growing in pots or other containers.

Zucchini varieties to try in your garden

When it comes to zucchini, there are so many delicious varieties to choose from!

If you’re looking for something new and exciting to grow in your garden this year, why not try one of these zucchini varieties?

Zucchini Black Beauty

Zucchini Black Beauty is a beautiful deep green colour with lovely white flesh inside. This is a tried and trusted heirloom variety that produces standard sized fruit on a bushy plant.

Black Beauty zucchini is perfect for grilling or baking.

Zucchini Costata Romanesco

Costata Romanesco zucchini has a light green colour with white stripes running down its length. It is an heirloom variety that originates from Italy. The fruit have a delicate flavour and firm texture that makes them ideal for eating raw in salads or cooked in stir-fries.

Zucchini Golden Zebra

Zucchini Golden Zebra are vigorous plants that produce bright yellow, cylindrical fruits, which are very flavoursome. Harvest regularly for a good crop.

Other yellow fruited zucchini varieties are: ‘Jemmer’, ‘Gold Rush’ and Parador.

Zucchini Tromboncino

Tromboncino is an Italian heirloom variety that is also known as “zucchino rampicante.” The fruits are long and slender, similar in shape to a trumpet. They can grow up to two feet long. Tromboncino zucchini has a mild flavour and can be eaten raw or cooked.

Storing fresh zucchini

As the summer season comes to an end, you may be wondering what to do with all of your extra zucchinis. If you’re like most people, you’ve probably given some away to friends and family members, but now you might be stuck with a surplus.

Luckily, there are plenty of ways to preserve your zucchini so that you can enjoy it long after the harvest is over. One option is to pickle your zucchini.

This will give it a tangy flavour that can be enjoyed as a snack or side dish. To pickle zucchini, simply slice it into thin rounds and submerge in vinegar for at least 24 hours.

You can then store the pickles in a sealed jar or container in the fridge for up to two months.

Zucchinis can also easily be frozen whole or cut into slices chunks; just blanch them first by dipping them into boiling water for 1-2 minutes before shock chilling in ice cold water (this helps preserve their colour).

Once dry, pop them into freezer bags labelled with the date and use within 6-8 months for best quality.

Frozen diced sliced zuccini also works well cooked directly from frozen – just add an extra minute or two onto cooking time.

So whatever route decide take, don’t let abundance go waste & get creative instead!

Conclusion

Zucchini are relatively easy to grow and will reward you with a good harvest from just a few plants. If you give them a nice rich fertile soil and you keep them reasonably well watered you can’t go very far wrong.