Top Of The Crops - Brocolli and Calabrese

Growing Broccoli & Calabrese in a Polytunnel

One of the great things about having a polytunnel is that you can easily grow brassicas all year round. While these crops can also often be grown outside, a polytunnel makes it easier to grow different forms of broccoli since it is easier to curtail loss to pests such as slugs and snails, and pigeons and other birds. A polytunnel can also be a useful place to sow broccoli prior to transplanting it to its final outdoors growing position. Calabrese is the type of broccoli with a large head that we are used to seeing in the summer months but there is also a range of other types of broccoli for over-wintering that sprout smaller heads in spring. Most broccoli is treated as an annual crop, though a perennial variety is also available.

Sowing and Growing Requirements For Broccoli & Calabrese

Whenever they are harvested, broccoli is always sown in spring and planted out after all risk of frost has passed – a polytunnel can give you an earlier crop of calabrese broccoli than it is possible to get outside. Seedlings should be sown in a seed bed or in pots at a planting depth of around 1cm and can be transplanted to their final growing positions when they are around 7cm high.

It is a good idea to sow broccoli and calabrese in a frost-free but cool position and if they have been indoors, they will have to be hardened off before they make their way outside. Plant transplants deeper than they were in pots and firm the soil well around them. Water in well and keep watered during dry periods. Broccoli and calabrese will also appreciate a high nitrogen organic mulch.

Calabrese broccoli should be spaced 40-60cm apart. The wider this distance, the larger the heads you will be able to achieve. Sprouting broccoli for spring harvest can be planted out at a spacing of 30-40cm. Companion planting may help to achieve higher yields. Alliums, for example, and herbs such as basil and thyme, can deter some common pests. Legumes may help with nitrogen requirements. Lettuce can be intercropped and harvested before the broccoli needs the space. Beetroots are said to be another good companion for broccoli.

Harvesting Broccoli & Calabrese

Calabrese broccoli can be ready for harvest from July-August. Cut off the heads when these have developed good size and shape but before the flower buds have begun to open. Do not lift the plants after harvesting the first heads – leave them alone and smaller secondary heads will form that can also be harvested. Sprouting broccoli will overwinter and can be a good crop to fill the gap between Brussels sprouts and cabbage in the spring. A perennial broccoli will last around 5 years or so and can look wonderful in a mixed border or in a perennial section of your polytunnel. Perennial vegetables can be a low-maintenance alternative to traditional annual crops.


Sowing time – April to May
Planting time – June to July

Expecting cutting time – August to October
Early varieties February to April

< Back

Swipe to scroll through tabs

About First Tunnels

We’re a close-knit bunch of skilled professionals who take an enormous pride in the quality and versatility of our products, But we’re enthusiasts too - we use our own products, and that means we’ve introduced lots of improvements and innovations over the years…based on first-hand everyday practical experience. We work hand-in hand with top growing experts. We even have our own allotment for some seriously hands-on gardening, often accompanied by communal summer and winter barbecues because all work and no play would be very dull!

Polytunnel Community

Reviewed by you, Followed by you, Liked by you and listened to by us. We have a strong online polytunnel community, 35k Facebook Fans, 10k Twitter Followers and over 3m YouTube Views. Our community of dedicated, passionate Polytunnel gardening friends, love to share their sowing tips, growing hints and harvesting secrets with each other. But more importantly for you, as a customer or a potential customer, you can post your comments in all their glory or gory details. Come and join the Polytunnel family.

Construction Help & Advice

Our six man construction team has a wealth of polytunnel construction knowledge and are more than happy to share tips and advice with any of our customers. Many of the team have been quite literally 'hands on' developing the First Tunnels vast array of construction videos and in depth instruction guides. Our construction team are available to answer your questions and help in whatever way they can. Simply call 01282 601253 on week days between 9am-5pm...PLUS weekend cover on 07801 601253, between 9am-5pm.

Frequently Asked Questions

We are proud of our products and the time that we have put in to making sure that all our products are first class. We understand that purchasing a polytunnel is a considerable investment, and whilst we have lots of help and advice on this site, Facebook, YouTube, Twitter and blog pages many people like to compare and contrast before they commit their hard earned cash to buying. To this end we have compiled a list of the most common questions and provide 10 top reasons why First Tunnels Polytunnels is the top choice.

Getting Growing

Part of the fun of owning a polytunnel is picking the brains of people who really know how to make the most of the real growing potential. So we're making it easy for you...with some of the best brains in the business! This site now includes features, produced exclusively for First Tunnels by Andy McKee and Mark Gatter - best-selling authors of 'How to grow food in your Polytunnel' and 'The Polytunnel Handbook'. We also have videos from BBC’s Gardeners’ Question Time presenter, Paul Peacock. We also have a host of growing guides from Sam Youd, presenter & judge for the Royal Horticultural Society & Tatton Park Head Gardener.

Other Useful Stuff

What better way to learn about company dependability, product quality and customer service than to hear it straight from other consumers? By giving customers the opportunity to share their First Tunnels shopping experience, we believe this is the best reflection of our companies’ product and service. To help reinforce credibility, popularity and reputation, we have subscribed to not one, not two...but THREE independent review companies. We value all feedback, good, bad or ugly and hope to build a long lasting relationship with our customer, through our high quality products and friendly service, to ensure they do not hesitate to order again and again with First Tunnels in the future.