Sowing and Growing Calabrese (Broccoli)

What is Calabrese?

Calabrese, better known as green broccoli in supermarkets, is a member of the brassica family, much like cauliflower and purple sprouting broccoli (PSB). It produces a large central head, and once this is harvested, the plant sends out plenty of side shoots for additional crops. Interestingly, the term “broccoli” is often used by gardeners to refer to the purple sprouting varieties, while supermarkets call the green version "broccoli."

Why Grow Calabrese?

At Wellies and Waxjackets, we love growing calabrese for several reasons. It’s incredibly tasty, packed with nutrients, and has a quick growing cycle compared to its brassica cousins. While PSB might take almost a year from planting to harvest, calabrese is ready in just 3-4 months, making it a great choice for multiple harvests in one season.

Not only is calabrese expensive to buy organically, but it's also heavily sprayed when grown conventionally. By growing your own, you ensure a fresh, organic supply for most of the year, with the added bonus of tasty side shoots after the main head is harvested.

How Many to Grow?

Calabrese tends to be harvested all at once, so for small households, you might only need one plant per person per week during its season. If you prefer to grow calabrese as a treat, two plants per month from March to June would suffice. However, if you plan to freeze it or have a larger family, you may want to grow more plants to take advantage of its generous side shoots.

Where and How to Grow Calabrese?

Calabrese thrives in full sun but can tolerate a bit of shade. It’s best grown directly in the ground, where it has room to develop large heads and produce side shoots. While it’s possible to grow it in containers, it won’t be as productive.

An annual plant, calabrese typically takes 90-120 days to harvest, depending on conditions. For a continuous supply, stagger your sowings throughout the year. Early sowings can even be ready in the middle of the "hungry gap," making it a fantastic addition to your garden.

Suitability for Different Growing Environments

Calabrese, like all brassicas, is quite hardy and can tolerate a bit of shade, but it absolutely loves full sun. With its short growing period and energy-intensive growth (forming a large central head and then side shoots), it really benefits from soaking up as much sunshine as possible.

It’s not ideal for container growing, but it can be done. If you decide to give it a go, make sure your plant has plenty of light, space, water, and food. You’ll likely get a decent head, but don’t expect many side shoots when grown in pots.

Lifecycle

Calabrese is an annual, typically sown and harvested in the same year. You can also sow it in autumn for a spring harvest. Usually, it’s a quick grower, taking around 90 days to reach harvest in perfect conditions, or around 120 days more typically. After the central head is harvested, the plant produces side shoots at the leaf junctions, often doubling the harvest over the next month.

Sowing and Harvesting Periods

Calabrese is one of those crops that benefits from staggered sowing to ensure a continuous harvest. The best yields come from specific sowing dates. Early sowings are fantastic for filling the "hungry gap" in spring, while summer sowings can produce abundant side shoots.

At Wellies and Waxjackets, we love early sowings as they take up minimal space during peak growing periods and bring variety to your plate when other veg are scarce.

First Earlies: Sow in September for a harvest in late April or early May. These are best grown under cover in an unheated greenhouse or polytunnel, then planted out in January or February. Early crops like this free up space for summer planting come mid-May.

Second Earlies: Sow in October for a mid-to-late May harvest. This sowing is very similar to the first earlies but may not require potting on more than once.

Early Main Crop: Sow in mid-February for a June harvest. If you've already sown early crops, you might skip this one as it can be tricky to grow without grow lights due to low light levels.

Main Crop: Sow in mid-March for a July harvest. This is the best time to sow if you don’t need to bridge the hungry gap. Main crop plants give the largest heads and, with enough space and water, produce plentiful side shoots.

Late Crop: Sow in June for an October harvest. We usually skip this sowing at Wellies and Waxjackets, as October is already a busy month with a good supply of other veg. But if you don’t grow much over winter, a late calabrese crop could be just the thing.

Where to Plant

Calabrese thrives in full sun or light shade. The sunnier the spot, the bigger the head and the more side shoots you’ll get. For best results, plant in well-draining soil, ideally neutral to slightly acidic.

How Many to Plant

Think about how many heads of calabrese you’ll want to harvest. Later sowings will provide a similar amount of side shoots as the main head, over the course of a few weeks to a month. The frequency of side shoots might continue for longer, but they will get smaller as time goes on.

How to Plant and Spacing

When planting your calabrese seedlings, remove any poor-quality lower leaves and plant them deep—bury the stem up to the first leaves for better stability. For just main heads, plant about 12 inches apart. If you want side shoots, give them more room—around 18 inches apart should do the trick.

Feeding and Watering

A good layer of compost before planting is ideal. Calabrese might also benefit from a bit of blood, fish, and bone for extra nutrition. Once planted, water deeply and regularly—aim for about 1 inch of water every two weeks, especially during dry spells in spring and summer.

Pruning and Maintenance

To keep your plants healthy, remove any lower leaves that touch the ground to reduce slug damage. Also, be sure to remove any leaves with fungal spots to prevent disease from spreading.

How and When to Harvest

Harvest the central head while the buds are still tight and firm. If the head starts to split or the buds open a bit, no worries—they’re still delicious! Side shoots tend to be looser than the main head, but they taste just as good. You can also eat the stems and smaller leaves, especially from the early sowings when brassica leaves can be scarce.

Storage and Cooking

For the freshest taste, eat your calabrese as soon as possible. If you need to store it, cool it down quickly, keep it dry, and store it in a sealed container in the fridge. Calabrese is brilliant when steamed, but there are loads of other tasty ways to cook it!

Dealing with Pests and Disease

Calabrese can attract pests like cabbage white butterflies and slugs, so it’s important to protect your plants. Check out our care guide for more tips on dealing with pests and diseases.

Removing the Plants

Once the side shoots slow down or you need the space for something else, it’s time to remove the plant. Cut the stem just below soil level and leave the roots in the ground to decompose.

What to Plant Before

The crops you plant before calabrese will depend on the succession you're aiming for. Here's a breakdown of what works well at Wellies and Waxjackets:

Succession	Plant After These Crops	Notes
First Earlies	Lettuce or spinach	Calabrese can be relay planted into your existing salad beds. It’ll take weeks before it overpowers spinach and lettuce.
Second Earlies	Summer-planted salads, carrots, parsnips, field beans	These crops finish in late winter, providing space for calabrese. Field beans grow vigorously but can be harvested in March; relay plant calabrese into them by mid-February.
Early Main Crop	Over-wintered spinach, carrots, field beans	As your spinach goes to seed in April, calabrese works well relay-planted into these beds. Field beans, when cut before flowering, leave nitrogen in the soil for calabrese to thrive.
Main Crop	Over-wintered beds	By May, most of your beds will be clear, so plant calabrese anywhere.
Late Crop	Spring lettuce, spring onions, over-wintered onions or garlic	Ideally, plant in a lightly shaded spot (like under a tree), allowing for autumn calabrese followed by winter crops like garlic or onions when the tree sheds its leaves.

What to Plant After

Once your calabrese is done, here are the crops that follow it best:

Succession	Plant Before These Crops	Notes
First Earlies	Summer undercover crops like tomatoes, peppers	You may not get a full harvest of side shoots before needing the space for summer crops.
Second Earlies	Summer outdoor crops like purslane, lettuce, beetroot, leeks	Be flexible with what comes after. Side shoots can be unpredictable in their production.
Early Main Crop	Late-autumn carrots, autumn lettuces, transplanted leeks	By July, plant crops like carrots for a late-autumn harvest or lettuces for autumn.
Main Crop	Autumn lettuces, early-winter spinach	In late August, consider lettuces and spinach for a nice autumn crop, or interplant calabrese with winter brassicas.
Late Crop	Garlic, over-wintered onions, winter lettuce	In late October, plant winter crops like garlic or onions. Undercover, winter lettuces and spinach are great choices.

What to Interplant With

At Wellies and Waxjackets, we often relay or interplant calabrese rather than interplanting other crops with it. However, if you’ve got open ground between your spaced-out calabrese plants (typically 18 inches apart), consider fast-growing crops like radishes or turnips.

Calabrese tends to have big, floppy leaves that quickly overshadow smaller plants, so choose wisely. Keep these interplanting tips in mind:

• Nutrient Sharing: Does one plant enhance the other’s access to nutrients?
• Pest Protection: Does one plant help protect the other from pests or diseases?
• Root Depth: Do the plants draw nutrients and water from different soil levels?
• Growth Rates: Do the plants grow at different rates, allowing one to be harvested before the other needs space?
• Shade and Wind Protection: Does one plant provide shade or wind protection to the other?
• Backup Plan: In case one plant fails, does the other succeed?

These principles of interplanting ensure your crops grow harmoniously together, making the most of your space and resources.