How to Grow Zucchini
Zucchini are now a common, summer staple in the vegetable garden. They are relatively easy to grow and they can be eaten raw added to salads or lightly steamed or roasted. Zucchini and marrows are actually the same thing - leave a zucchini to mature on the plant and it will become a marrow! Modern zucchini varieties have been bred to produce a lot of small, tasty fruit.
When’s the best time to plant zucchini?
Zucchini grows best in warm weather and should only be planted once the risk of frost has passed. In Australia, this is typically spring through early summer, when soil temperatures consistently stay above 15°C (aim for 18°C or above for more reliable germination). Planting and harvest windows vary by climate zone:
- Cool: plant Oct–Dec, harvest Dec–Mar
- Temperate: plant Sep–Jan, harvest Nov–Apr
- Subtropical: plant Aug–Jan, harvest Oct–Mar
- Tropical: plant Apr–Aug (dry season), harvest Jun–Oct
- Arid: plant Aug–Oct and Feb–Mar
Zucchini plant varieties
There are numerous excellent zucchini varieties including those producing round or yellow fruit. Among them are: Black Beauty, Blackjack, Cocozelle, Golden (yellow fruit), Greyzine (pale colour) Long Florence, Tromboncino and Solar Flare (golden).
What you’ll need to start growing zucchini
You don't need much equipment to plant and grow a zucchini plant. Here are the basics:
- Garden fork and spade
- Trowel
- Compost or soil improver
- Tomato & vegetable fertiliser
- High potash fertiliser
- Zucchini seed
How to grow zucchini:
Planting zucchini & cultivation
Zucchini plants prefer a sheltered position in full sun and a fertile soil that holds plenty of moisture. They are reasonably large plants, so need plenty of room. Space them up to 1m apart. There are some more compact varieties available for small space gardens and these are ideal for growing in containers.
For best results, they can be grown in planting pockets. About 2 to 3 weeks before sowing seed or planting out seedlings, dig a hole 30cm square and deep and fill with a mixture of compost or soil improver mixed with soil. Leave a low mound at the top and sprinkle a vegetable plant food over the soil.
As zucchini need plenty of water, sink a 15cm pot alongside ach plant when sowing or planting out. Watering into the pot ensures moisture goes down to the roots and doesn't sit around the neck of the plant, which can lead to rotting. It also keeps water off the foliage which helps reduce problems with powdery mildew.
How to grow zucchini from seed
Growing zucchini from seed is one of the easiest ways to produce a productive crop, and it can take as little as 6–10 weeks from planting to harvest under ideal conditions.
Step 1: Prepare and sow seeds
Plant zucchini seeds directly into the garden once the soil is warm, or start them in pots if conditions are still cool. Sow two or three seeds about 2–3cm deep in small mounds or planting holes enriched with compost. You may grow two plants per mound if space permits.
Step 2: Germinate seeds
Keep soil consistently moist but not waterlogged. Seeds usually germinate within 7–10 days in warm conditions. Avoid overwatering, as this can cause seeds to rot before sprouting.
Step 3: Thin seedlings
Once seedlings emerge, thin to the strongest plant per mound. This ensures each plant has enough space, nutrients, and airflow to grow properly.
Step 4: Transplant (if started in trays)
If started indoors, transplant seedlings once they have at least 2–3 true leaves. Handle carefully to avoid damaging roots and plant into well-prepared soil.
Step 5: Water and feed regularly
Zucchini are heavy feeders. Keep soil consistently moist and apply a liquid fertiliser once flowering begins to support fruit development.
Step 6: Maintain growth
As plants grow, mulch around the base to retain moisture and suppress weeds. Regular care will encourage continuous flowering and fruiting.
Step 7: Harvest
Zucchini can be harvested once fruit reaches 10–15cm long, typically within 45–60 days of sowing, depending on variety and conditions.
How to care for zucchini
Keep the soil constantly moist by watering around the plants - not over the foliage - whenever needed. Once the first fruit starts to swell, feed every 10-14 days with a high potash liquid fertiliser.
How to harvest zucchini
Harvesting zucchini at the right time is key to getting the best flavour and encouraging continued production. Zucchini grow quickly, so regular picking is important.
Zucchini may be susceptible to the following problems: lack of fruit set, young fruit rotting.
When should you harvest zucchini?
Zucchini should be harvested when they are young and tender, usually around 10–15cm long. At this length they are at their sweetest and most tender. If left too long, they become large, watery, and less tasty.
How do you harvest zucchini?
To harvest zucchini, use a sharp knife or secateurs to cut the fruit from the plant, leaving a short stem attached. Avoid twisting or pulling, as this can damage the plant. Check plants every 1–2 days during peak season, as fruit can grow very quickly.
How often should you harvest zucchini?
Zucchini should be harvested regularly, often every couple of days once production begins. Regular picking when they are small ensures a long cropping period over several months.
Common zucchini pests, diseases & growing problems
| Powdery mildew |
Powdery mildew on zucchini is a common problem. This is a fungal disease that appears as a white powdery deposit on the leaves, stunting growth and causing leaves to shrivel. Drought-stressed plants are more susceptible.
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| Yellow zucchini leaves | Older zucchini leaves often turn yellow and drop off the plant. This is not a cause for concern as they will be replaced by new growth, but also see Cucumber mosaic virus below. |
| Cucumber mosaic virus |
Zucchini leaves turning yellow can also be due to cucumber mosaic virus. This causes deformed, stunted leaves with a characteristic 'mosaic' yellow patterning. Affected plants produce few or no flowers, and any fruit that develop are small and inedible.
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| Grey mould/ Bortrytis mould |
Grey mould is a fungal disease that appears as powdery grey mould at the stalk of zucchini, gradually covering the whole fruit, which then rots.
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| Zucchini rotting when small or not setting |
Zucchini fruits can appear to start swelling but then rot or drop off the plant while still small. This occurs when the flowers are not pollinated, and is usually more of a problem early in the season.
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| Slugs and snails |
Slugs and snails will eat the leaves of young zucchini plants, and can be identified by the slime trails that they leave, as well as the damage they do.
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Growing Zucchini FAQs
When’s the best time to plant zucchini?
The best time to plant zucchini is in spring through early summer, once the risk of frost has passed and soil temperatures are consistently above 15°C (ideally 18°C+ for reliable germination). Planting windows vary by climate zone - roughly September to January in temperate areas, August to January in the subtropics, and April to August (the dry season) in the tropics. Warm soil and stable temperatures are essential for strong germination and healthy growth.
How long does zucchini take to grow?
Zucchini grows quickly and is usually ready to harvest within 6–10 weeks of planting. Warm conditions, regular watering, and feeding can speed up growth.
Do zucchini need full sun?
Yes, zucchini grow best in full sun. Aim for at least 6 hours of direct sunlight per day to support strong growth and fruit production.
Can you grow zucchini in pots?
Yes, zucchini can be grown in large pots as long as they have enough space, good drainage, and regular watering. Choose a container at least 40–50cm wide.
When's the best time to pick zucchini?
Zucchini should be harvested when they are young and tender, usually around 10–15cm long. Picking them at this stage ensures the best flavour and texture, and encourages the plant to keep producing.
How do you harvest zucchini?
Use a sharp knife or secateurs to cut the fruit from the plant, leaving a short stem attached, rather than twisting or pulling it off.
How often should you harvest zucchini?
During peak growing season, zucchini should be harvested every 1–2 days. Regular picking keeps the plant productive and prevents fruits from becoming oversized and tough.
Can you grow zucchini from seeds?
Yes, zucchini is commonly grown from seeds and is one of the easiest vegetables to start from scratch. Seeds can be sown directly into the garden once the soil is warm, or started in pots and transplanted once seedlings are established.
How long do zucchini seeds take to germinate?
Zucchini seeds usually germinate within 7–10 days in warm conditions, provided the soil temperature stays above 15°C.
