Broccoli is a healthy, tasty green vegetable from the cabbage family with loads of goodness to offer. Its versatility and richness in fibre, antioxidants and Vitamins K, C and B9 make it a popular choice in many cuisines and dishes.
The UK has an ideal climate for growing broccoli, so why not stop relying on the supermarket for your green broccoli goodness and start growing it in your garden or polytunnel instead? Depending on when you sow the seeds, you can enjoy a harvest of this vegetable in either spring or autumn (or both!).
Before we delve into the details of how to grow your own broccoli, we need to clear up a common source of confusion. The green-domed variety known commonly as 'broccoli' is actually 'calabrese'. The plant known as 'broccoli' in gardening terms is also known as 'sprouting broccoli' and produces smaller clusters of purple or white heads on leafy stem tips, which taste similar to the green 'calabrese' type you can get in supermarkets, but slightly more bitter.
When to plant your purple sprouting broccoli or calabrese
It's generally best to sow broccoli or calabrese seeds in the spring, any time between April and June. For a long-lasting harvest, plant them in several rounds across spring.
If you're planting Arcadia broccoli, the type that can grow over winter for a harvest in spring, the best time to plant it is 6-8 weeks before the date when you expect the last frost. These types are hardier than other varieties.
How to plant broccoli or calabrese
You can plant them directly outside if you prepare your soil well with a general-purpose fertiliser at a ratio of 150g per square metre and ensure that they are positioned so they can get full sunlight. Alkaline soil is best for healthy broccoli and calabrese crops (specifically, a pH of 6 or 7 is best. To make soil more alkaline, try applying some lime!). Your seeds should be planted in 2cm-deep holes, with three seeds in each hole. The holes should be 30cm apart with 45cm between rows. This is because the crops tend to develop plenty of side shoots, which need space to spread out.
Once your seedlings have grown larger, you can thin them out a bit so that you're left with the healthiest crops only.
After you plant the seeds, give them a light watering but be careful not to overdo it. Rather than using a watering can, you're less likely to overwhelm the seedlings if you water them from a plastic bottle that has a few holes punched into the cap.
The advantages of growing your broccoli or calabrese in a polytunnel
Though you can direct-sow broccoli and calabrese if you want to, you must be aware that they can be very attractive to birds, cabbage white caterpillars, and cabbage root fly, among other pests. To keep them healthy and ensure there's a generous harvest for your kitchen, try planting them in a polytunnel. Not only do they guard against the perils of the crop's position in the food chain but they also make it easier for you to control the growing temperature, meaning that a bout of bad weather is less likely to impact your seedlings as they mature.
Once they're bigger, you may like to transport them from the polytunnel to a more open outdoor space. The best time to do this is when the possibility of a frost has become slimmer.
How to care for your broccoli or calabrese while it grows
You will need to water your broccoli or calabrese more attentively when they are younger. Once they've become better established, you can reserve watering for periods of dry weather. Even then, you must be careful not to overwater them and to focus the water on the surrounding soil, rather than the crop itself. You can enhance the crop and lower watering requirements by surrounding them with organic mulch.
Broccoli plants grow best when the soil is rich in nitrogen and this can help them to grow better-sized heads. Keeping the soil topped up with compost, well-aged manure or a fertiliser that's high in nitrogen will aid this.
There are a few companion plants that you could consider planting alongside your broccoli for the best results. These include:
- Nasturtiums and geraniums: these flowers repel some of the pests that broccoli plants attract, such as cabbage worms. Nasturtiums are light feeders, so they won't compete for nutrients either.
- Garlic: this crop's strong scent is great at deterring pests.
- Onions or shallots: many think that planting onions alongside broccoli plants improves the flavour.
- Rhubarb: this is another crop that can help deter some of the pests that commonly plague members of the brassica family, such as broccoli and calabrese.
When and how to harvest your broccoli or calabrese
You'll know your sprouting broccoli is ready to harvest when you see multiple clusters of pink, purple or white clusters. Depending on when you planted them, your harvest is likely to be ready any time from late summer onwards. With winter varieties, you can look for the signs that your harvest is ready as late as spring.
If it's calabrese that you are harvesting, look for the big, green heads and a height of around 60cm. They should be ready in late summer-autumn, 3-4 months after you first planted the seeds. To collect the harvest, cut off the green heads and then watch for further heads to appear from side shoots, so that you can enjoy a harvest that is extended by up to eight weeks.
Cut your broccoli or calabrese at the stem about 10cm below the head and take care to use one clean cut so that you don't diminish the plant's chances of growing more heads.
How Premier Polytunnels can help you
If you're thinking about growing broccoli but don't want to waste your time and personal investment in crops that take a hit from pests and unexpected weather conditions, you may benefit from one of
our polytunnel solutions. In the early growing stages of growing broccoli especially, this is a reliable way to get those seedlings off to a good start.
With a polytunnel, you don't have to wait until after the last frost to get planting, either, as the plants will have more protection.
If you have any questions about our products or are seeking general advice, you can give our friendly polytunnel experts a ring at
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request a call back or
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