If you are already a polytunnel gardener then it is likely that you have grown at least some radishes in your polytunnel. Most likely, you will have grown traditional round red radish varieties. Perhaps you may also have grown French breakfast type radishes. If you have not already done so, this month could be a great time to branch out and grow some Daikon radishes in your polytunnel.
What Are Daikon Radishes?
Daikon radishes are a type of oriental radish. Originally native to continental East Asia, this root crop is now grown around the world. And it makes a top crop for winter in your polytunnel here in the UK.
Raphanus sativus var. longipinnatus is mild in flavour, with a long, white root. It can be eaten raw or cooked. Sometimes, it is also known as Chinese radish. The name Daikon comes from its Japanese name and can be translated literally as ‘big root’.
Varietals such as ‘Long White Icicle’ are available as seed here in the UK. These can be grown very successfully outdoors in southern England, and inside as polytunnel in other parts of the country. There are a number of interesting heritage seeds that you could consider, and it is also pretty easy to collect seeds so you can grow your own again next year.
Why Grow Daikon Radishes?
Daikon radishes can be grown as a culinary crop. As you will discover later in this article, there are a range of ways to eat and enjoy them. Daikon radishes are not as easy to find in supermarkets as the more common radish varieties. So growing them is a good way to try something a little different and add more variety to your diet.
Eating daikon radishes is great for your health. These vegetables are low in calories, yet pack quite some nutritional punch.
However, this is not the only reason to grow these radishes in your polytunnel. Certain varietals of Daikon radish are ideal for growth as a green manure or cover crop. They can be very useful in a no dig garden. Their deep, large roots effectively break up the soil structure, bringing better aeration and essentially cultivating your soil for you to a deep level. This can be especially beneficial in areas with heavy clay soil.
Using Daikon radishes as a winter cover crop in your polytunnel can also bring nutrients lower in the soil profile up to the surface layers. They are a type of dynamic accumulator, and can work well alongside leguminous nitrogen fixers that are planted as a winter green manure – such as broad or field beans.
Whether you are growing them as an edible crop, or as a winter cover crop/ green manure, sowing towards the tail end of the summer season can help make the most of your space. They can provide a crop late in autumn, through winter and into early spring, before they make way for spring sown crops.
Radishes of all kinds, of course, also make for great companion crops. They can repel certain pests and act as trap crops for others.
Another reason to grow radishes of all sorts in your polytunnel is that they are great value for money. And they can help you to make the most of your space. Even when they are also serving other functions, there are a number of additional yields to be obtained. All parts of the plant are edible – not only the roots but also the leaves, pods and seeds (sprouted, these are of great nutritional value).
How To Grow Daikon Radishes
Daikon radishes are best sown between July and September. There is also another window of opportunity to sow them in late winter. They are fully hardy over the winter months, and take little care. In fact, they thrive on a little neglect and will tend to do well even if you don’t spend as much time in your winter polytunnel as you intended.
Sow the seeds of Daikon radishes around 1 inch deep and 1 inch apart. Then as the radishes grow, thin them to a spacing of around 2-4 inches apart. (Remember, you can eat the plants you thin.) The eventual spacing will depend on why you are growing the radishes. If you are growing them for large roots, a wider spacing will be required. But if you are using them mainly to break up clay soil, then spacing is obviously less important.
Make sure that you provide a consistent water supply, but do not overwater. These cool season crops don’t like heat and drought. But as long as they are not starved of water entirely, they should thrive.
Harvesting and Using Your Winter Radishes
Daikon radishes that are to be used for culinary use are usually harvested after a couple of months. They can survive a light frost, and should survive and usually keep growing through the winter in an unheated polytunnel in the UK.
Daikon radish roots can be sliced finely and eaten raw. They can also be boiled or roasted and used in a range of versatile ways in your kitchen. They are common ingredients in China, Japan and other Asian cultures, and are a key ingredient in kimchi, and they can also be used in other fermentation recipes.
The leaves can also be cooked and eaten. Don’t be put off by the texture of the raw leaves. Once cooked, these are similar to other green vegetables from your polytunnel.
If you let the radishes set seed, you can also have an abundant – staggeringly abundant – supply of radish pods come spring. These are another versatile kitchen ingredient.
Other Radishes To Grow in Your Polytunnel This Winter
Daikon radishes are only one of the types of radish that you can grow in your polytunnel this winter.
You could also consider growing watermelon radishes, which are a related oriental radish which forms large globes. The origins of the name becomes clear when these globes are cut open.
And other very useful winter plant is the black radish. Black radishes are another interesting type of radish to try. Raphanus sativus niger is another radish that can work well in a polytunnel during the coldest months. The roots store and keep well. But they can also remain in the ground to be harvested as required during the winter. Some varieties have hot and spicy roots, while others are much milder.
Even if you are not fond of spicy radishes, there are oriental radishes that you can try that have a much milder flavour. Some can be roasted for a surprisingly sweet and only mildly spicy taste very different from the hot radish flavour you might expect. If you have only grown radishes of the typical summer types, try them. You will find them very different to their summer counterparts.
If you have tried growing daikon radishes in your polytunnel, share your experiences in the comments below. Do you have any tips, tricks or recipe suggestions to share? We’d love you to share these with us and our readers.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.