How to grow zucchini in Australia

Zucchini is one of the most rewarding crops you can plant in your vege patch.

Growing zucchini can be fairly straightforward, but if you’re new to gardening it may be difficult to get started.

This guide will cover everything you need to know to grow zucchini in Australia.

Zucchini fact list

  • Family: Cucurbits
  • Genus: Squash
  • Plant type: Annual
  • Height: Up to 3m
  • Climate: Grows best in warm climates
  • Sun: Full sun
  • Soil: Rich and well-drained soil
  • Water: Water generously 2-3 times per week
  • Feeding: Apply a liquid fertiliser when flowers appear followed by monthly liquid feeds

Although zucchini can grow in both spring and autumn, it’s considered a warm season crop: it grows best when daytime temperatures range from 20 to 30 degrees Celsius.

When to plant Zucchini in Australia

The best time to grow zucchinis in Australia is during spring and summer. In temperate climates (which all the major cities fall into), they should ideally be planted in September or October.

In some parts of Australia, you can still plant in autumn, but only if the soil temperature stays above 15 degrees Celsius.

In colder areas, plant from October to December.

You should never plant zucchini in cold weather as they may take a long time to germinate or fail completely to sprout after planting.

Planting in places that might get frost can also damage your seedlings or fruit and stunt their growth.

How to grow Zucchini from seeds

Zucchini is a part of the family Cucurbits, which also includes gourds, pumpkins, and cucumbers. The Squash genus of Cucurbits has about 25 species.

The zucchini plant can grow up to 2m tall and produce fruits with yellow or green skin and white flesh. The flowers are small and yellowish-green in colour with five petals each.

Zucchinis are usually grown in raised mounds of soil. You’ll need to space your mounds about 40cm apart.

Plant 3-4 seeds per mound at a depth of 2cm. Water well.

It takes 1 – 2 weeks for zucchini seeds to germinate at 15°C+ soil temperature with sufficient moisture levels present.

After a couple of weeks, the seedlings should emerge.

When they do, thin the seedlings to two per mound (keep the strongest ones).

Water generously 2-3 times per week, enrich the soil with aged manure and compost, and apply a liquid fertiliser when flowers appear.

Zucchini pollination

Zucchini needs to be visited by a lot of bees or other pollinators for successful pollination.

If not, the fruit won’t grow, and it may turn yellow and start to rot.

Avoid this problem by making sure you include flowers around your vegetable garden that encourage pollinating insects.

If this isn’t an option (or if you really want to be sure), you can hand-pollinate the flowers.

Here’s a video showing the process for hand pollination:

How to care for Zucchini

To keep your Zucchini plant happy, you’ll need to provide the following essentials:

  • Watering – Water regularly and thoroughly, but most of all don’t let the soil dry out. It’s good to check at least every other day over summer.
  • Fertiliser – Use a balanced fertiliser such as one labeled 10-10-10 according to the directions on its packaging.
  • Sun – Zucchini needs at least 6 hours of sun per day to thrive. If it is not getting enough sun, the fruit will be small and poorly developed.
  • Soil – Zucchini needs well draining soil with plenty of compost or manure mixed in before planting time. It also requires a constant supply of nutrients so you can mix some well rotted manure into the soil around it as well as using fertiliser as mentioned above.
  • Spacing – To ensure even growth and maximum air circulation between plants, space the mounds 40 cm apart.
  • Pruning – You can prune this plant lightly throughout the season if you like; just cut off any excess leaves that may be causing shading or overcrowding issues.

How long does Zucchini take to grow?

In general, zucchini plants germinate quickly and grow in size rapidly.

Under ideal conditions, you can expect your plant to begin producing its first fruit (the zucchini itself) approximately fifty days after planting (though sometimes it can take as long as seventy).

This is when the plant begins to put all of its energy into growing the fruit. Upon harvesting, the plant will continue making new flowers at a steady pace for about a month and a half; then it will slow down.

A second or third crop may be possible if you feed your plant some fertiliser during this time and water it regularly.

Regular harvesting will encourage the continuous production of fruit.

When to harvest Zucchini

You can harvest the zucchini when they are small, young and tender, or you can wait until the fruit is bigger.

However, the fruit will taste best if harvested when it’s small and fresh.

If you want your zucchini to taste its best, harvest when they are about 15cm long and still tender. Do not wait for the rinds to harden.

It’s also a good idea to harvest in the morning—the plant will be more hydrated at this time (and less likely to damage) than if you were to pull out a zucchini during a hot afternoon.

How to grow Zucchini in a pot

If you have only a small outdoor space or want to grow your zucchini on the patio, growing in containers is an option.

Zucchini is easy to grow and if planted in a sufficiently sized container it can produce an abundance of fruit.

A zucchini will need at least one square meter of space, so select a deep pot that’s about 60cm across and 40cm deep. The pot should allow water to drain freely.

Fill the container with premium potting mix, create a mound in the middle, and plant two seeds directly into it.

Don’t forget, you will need to water them more frequently than if they were planted in open ground because pots dry out much quicker.

Zucchini pests and diseases

You hopefully won’t have any issues with pests of diseases impacting your zucchini crop, but if you do, it will likely be a fungal disease like Powdery Mildew.

Powdery mildew is a white powder-like coating that appears on leaves and stems. The leaves will usually become distorted and die.

Affected plants should be cut back and destroyed, and make sure to clean up all the debris around the plant.

To prevent it from occurring, keep the area around plants clean, water in the morning so foliage dries out during the day, and don’t overcrowd zucchini plants.

You can also make a solution of milk and water (1:9 ratio) and spray this on all of the leaves of the plant 2-3 times a week.

Practising crop rotation is another strategy for reducing the likelihood of pests and diseases affecting your plants.

Another problem you may run into is snails and slugs eating your zucchini seedlings, so be vigilant in the first few weeks.

Zucchini companion plants

Zucchini plants can be grown alongside the following companion plants for mutual benefit:

  • marigolds
  • mint
  • onions
  • nasturtiums
  • peas
  • radishes
  • thyme
  • dill
  • garlic
  • oregano

Zucchini appearance and characteristics

Zucchini are shiny, dark green, and cylindrical.

As a summer squash, zucchini are usually harvested when immature (10–20 cm long, 2–4 cm in diameter) and slightly tapered with a smooth skin.

If left to grow larger, they can be somewhat bitter tasting.

This green beauty may look innocuous, but it’s actually packed with vitamins and minerals. In addition to being an excellent source of vitamin C (more than 100% of your daily recommended intake per half cup), zucchini is a good source of iron and magnesium.