How to Grow Zucchini

Zucchinis need at least 6 hours of sunshine a day, so choose a nice sunny spot. Each plant needs approximately 70 cm of space (70 cm long x 70 cm wide) and growing one Zucchini plant per person will satisfy most of your Zucchini needs. If you don't have a vegie patch, you can also grow Zucchinis in a garden bed (there's no rule that says vegies should only be grown in a vegie patch!).

Improving the soil before sowing seed will give the plants a great start. Soil improvement is as simple as mixing 2 handfuls of Yates Dynamic Lifter Soil Improver & Plant Fertiliser into each square metre of soil.

Whether you love the very popular dark green ‘Blackjack’ Zucchini , or light green pear-shaped Lebanese Zucchini, Zucchinis are really easy to grow from seed. The seeds are not too small and are easy to handle.

To sow seed, dig 2cm deep holes, 70 cm apart, and place 3-4 seeds in the base of each hole and cover with soil. Gently press down so there's good contact between the soil and the seeds, and then water.

Keep the soil moist (but not wet) and seedlings will start to emerge in around 10 days. If multiple seedlings emerge from the one hole, gently remove the smallest, leaving the two biggest and strongest seedlings.

If you'd prefer to grow your own Zucchini seedlings that you later transplant into the garden, fill small pots or punnets with Yates Specialty Potting Mix Cuttings & Seeds and sow seeds 2cm deep.

Place the pot or punnet in a warm sunny spot and keep the mix slightly moist. Once the seedlings are large enough to handle, gently remove, dig holes in the soil big enough to accommodate all the roots.

Plant the seedlings so the roots are covered but not the stem. The final level of soil around the seedlings should be at the same depth as it was in their punnet or pot. Then water in well.

Snails and slugs are one of the biggest dangers to young Zucchini seedlings, particularly during damp weather. You can protect seedlings with a light sprinkling of Yates Snail & Slug Bait. It's also beneficial to apply mulch, like sugarcane or pea straw, around the base of the plants. Mulch helps to keep the soil moist.

Around 4 weeks after sowing, your Zucchinis should be small plants.

Your Zucchini plants will be hungry and need feeding to make sure they have enough nutrients to promote lots of healthy leaves, and get them prepared for flowering and developing Zucchini fruit.

Feeding isn't difficult or time-consuming and will help make a big difference to the health and productivity of your plants. Every week, dilute 2 capfuls of Yates Thrive Natural Vegie & Herb Concentrate in a 9 litre watering can and apply around the base of the plants.

Avoid planting anything from the cucurbit family including Cucumbers, Pumpkins, Melons, and Squashes in the same bed for a year or so. You could plant a green manure crop and let the bed rest for a season. Otherwise plant something from the Carrot family such as Carrot, Celeriac, or Parsnip; or from the allium family such as Onions, Garlic, or Leeks.

As your plants mature, you will see bright yellow flowers. There are two different flowers that grow on the one plant - male and female – so you don’t need more than one plant to grow Zucchini fruit. Male flowers are on a long stalk and female flowers have a tiny Zucchini at the base.

Pollen needs to be moved from the male flowers to the female flowers, for the Zucchini to develop. Bees and other pollinating insects usually do a good job in moving pollen around, but you can also try hand pollinating to help, and improve the number of Zucchinis you'll get.

Using a soft small paintbrush, gently wipe around the inside of a male flower to collect pollen and then wipe the brush around the inside of a female flower. Do this multiple times, between lots of flowers. It's best to try hand pollinating in the morning when the flowers are open.

Zucchinis produce male flowers when young and later female flowers as they mature. Once there are male and female flowers on the plant at the same time, the fruit should start to appear after then.

It’s best to harvest Zucchinis when the fruit is around 15 cm long and still small and tender. Zucchini fruit grow very quickly and can become huge in a few days.

The fruit develops a tough skin and large seeds inside as it grows, so the small Zucchinis are definitely best. Check and harvest your Zucchinis regularly. Frequent picking also helps promote a longer harvest season.

Zucchinis grow best in the garden, but can still grow well in pots.

Zucchinis need at least 6 hours of sunshine a day, so choose a nice sunny spot for your pot, at least 30 – 40 cm cm in diameter.

Fill the pot with a quality potting mix, like Dynamic Lifter, which will help give the Zucchini plants a great start.

To sow seed, dig a 2 cm deep hole in the centre of the pot, place 3-4 seeds in the base of the hole and cover with potting mix. Gently press down so there's good contact between the potting mix and the seeds, and then water.

Keep the potting mix moist (but not wet) and seedlings will start to emerge in around 10 days. If multiple seedlings emerge from the one hole, you can gently remove the smallest, leaving the two biggest and strongest seedlings.

See steps 4 onward in How to Grow Zucchini in a Garden for further information.

Small Zucchini fruit starting to yellow and wither can be a sign that the female flower wasn't pollinated. Try the hand pollination technique outlined above.

Zucchinis can also develop a condition called Blossom End Rot, where young fruit yellows, withers and starts to rot. Blossom End Rot can occur if the plants don't have access to enough moisture (which affects calcium supply). Make sure you're watering your plants regularly, to keep consistently moist.

Zucchinis are prone to a few common pests, including Aphids and 28 Spotted Ladybirds.

Aphids are tiny green, brown, yellow or black sap-sucking insects that cluster on leaves and flower stems. They can damage leaves and flowers and plant health will suffer.

As soon as any Aphids are noticed, spray the plants with Yates Nature's Way Vegie & Herb Spray. It's an insecticidal soap, based on natural vegetable oils, and is approved for use in organic gardening.

Another common Zucchini pest is the 28 Spotted Ladybird, which is a pest Ladybird that chews through and damages leaves. Pick these Ladybirds off by hand.

Protect Zucchini plants from Snails and Slugs with Yates Snail & Slug Bait. You can also cover young plants with a clear plastic cover. Try using a 2 L plastic bottle with the bottom cut off and place it over the top of the plant.

A disease that commonly affects Zucchini plants is Powdery Mildew, particularly as the leaves age and if the weather is damp or humid. Large Powdery Mildew infections cause leaves to yellow and die prematurely.

Help reduce Powdery Mildew by watering plants around the base, rather than over the leaves, and control Powdery Mildew by spraying the plants every 7-10 days with Yates Mancozeb Plus Garden Fungicide & Miticide.

Symptoms of Downy Mildew include yellow and brown spots that start on the new leaves, and sometimes a fine purple-grey mould on the underside of the leaf.

Avoid overhead watering, and water only in the morning. As soon as you notice the disease, spray with Yates Liquid Copper.

Zucchini fruit can become bitter if the plants are moisture stressed, so make sure the soil or potting mix is kept consistently moist. Help fix water repellent soil and move moisture down into the root zone by applying Yates Waterwise Soil Wetter around the plants.