Zucchini are renowned for being outrageously prolific – just two or three plants are likely to keep a small family supplied with these versatile fruits all summer long. If you haven’t started them off already, don’t panic! There’s still plenty of time. Read on or watch our video to discover how to grow zucchini, from sowing to glorious, magnificent harvest!
Types of Zucchini
Zucchini are warm-season crops with compact, bushy or trailing varieties to pick from. Compact types are good for containers – indeed anywhere you don’t have a lot of space – while trailing types may be trained as climbers to grow up supports such as trellis or wire mesh.
Green zucchini are always going to be popular, but try a few of their more charismatic cousins as well, including varieties with yellow fruits, striped or ribbed fruits, and even round fruits.
Where to Grow Zucchini
Zucchini are members of the squash family, so they need to be bathed in warmth and sunshine to thrive. Shelter them from strong winds too, so bees and other insects can go about pollinating the flowers in peace.
Their robust growth and big leaves make them hungry feeders. Add plenty of garden compost or well-rotted manure to the soil before planting. In fact, you can even plant zucchini on top of a compost heap – if you won’t be needing it till autumn that is. Or prepare planting pockets: a few weeks before planting dig out a hole, fill it with compost, then return some of the soil, along with a handful of organic fertilizer. The nutrient-rich filling will prove a veritable feast for the plants growing in it!
How to Sow Zucchini
You can sow zucchini directly outside after your last frost date. Make a depression into the soil about half an inch (1cm) deep then drop in two seeds. Cover them back over and pop a clear jar or half a plastic bottle over the top to serve as a miniature greenhouse to speed things along. Once the seedlings are up, remove the weakest to leave just one in each position. Direct sowing like this works just fine, but I prefer to get a bit of a head start by sowing under cover, in the greenhouse, a couple of weeks earlier.
Fill pots or plug trays with potting mix and sow one seed per pot or plug on its edge. They will germinate quickest with a little warmth, but so long as you can guarantee a frost-free environment they’ll eventually push through.
You can also sow into seed flats or trays to separate out and pot on after germination. Do this as soon after germination as you’re able to handle them, before the roots become entangled. Fill your pots and, holding the seedling by its leaves, not the stem, feed in the potting mix around the sides. Firm in and water.
But when should you sow? Our Garden Planner can help. It pulls data from your nearest weather station, which means it automatically works out your last frost date. By sowing under cover – in a greenhouse or tunnel for example – you can start even sooner if you don’t mind potting young plants on a few times before it’s time to plant them outside.
How to Plant Zucchini
Prepare plants for life outdoors by gradually acclimatizing them for one to two weeks beforehand. To begin with set them out in a sheltered spot during the day for a short while, then gradually increase the length of time they’re out for. Plant once there’s no risk of frost.
Plant zucchini at least two feet (60cm) apart. In our Garden Planner the minimum space required by each plant is indicated by the shaded area around it, so you can get your spacings spot on. Bear in mind that many varieties need more space than this, so check the exact requirements of what you’re growing.
Planting couldn’t be simpler. Dig a suitable-sized hole into prepared soil. Remove the young plant from its pot. Pop it into the hole and feed the soil back in around it. Finish with a thorough watering.
Incidentally, a great tip is to insert a pot into the soil right next each plant. By watering into the pot the water stays put and passes out through the drainage holes into the soil near the roots, rather than just running off over the surface. I also find that adding a rough mulch of organic matter helps to catch and hold onto the water, as well as making the soil less prone to forming a hard crust that water can’t penetrate.
Caring for Zucchini
Keep your zucchini well-watered, and top up mulches occasionally to help lock in soil moisture for longer. Plants tend to produce only male flowers at first, and pollination can also be slow to start with anyhow, particularly in cool or damp weather. If pollinating insects are thin on the ground – or rather the air – you can hand pollinate flowers by transferring the pollen from a male flower direct to an open female flower.
In fact, the flowers make good eating too, typically stuffed or simply battered then fried. But only pick the male flowers – that’s the ones without a bulge behind them – or else you won’t get any fruits!
Powdery mildew can be an issue on the leaves later on in the season. Keeping plants well-watered and leaving plenty of space between them for good airflow should slow the spread of this disease. If your zucchini does get powdery mildew, don’t worry too much, as plants will usually cope.
How to Harvest Zucchini
Begin cutting or twisting off zucchini while the fruits are still quite small. Smaller fruits have a denser, nuttier flesh and, believe me, are far superior in taste. If you’ve been put off zucchini before, it’s probably because they were left to grow into big watery marrows! Check plants often – every other day at least – and pick fruits as soon as they reach a useable size. This is the best way to avoid those overbearing gluts!