GROW Great Plants All Year Round — Winter Crops in Northern Europe

Garlic — photo from the GROW Observatory Share My Planting Calendars facebook page

Alice Ambler tells us about her first year’s winter growing, shares some top tips she’s discovered, & introduces the edible plant calendar GROW Observatory is developing.

I am Alice Ambler, a citizen science researcher with the GROW Observatory. My background is in environmental hazards, but I’ve really developed a keen interest in food growing and citizen science. I spend A LOT of time on my allotment. With the GROW Observatory, I co-create educational materials for learners to follow on our online courses on Future Learn. I love communicating with growers online through Future Learn and the GROW Observatory Forum. It is amazing to see what growers are up to around the world, and not just in this temperate climate.

Here I’ll share my experience of my first year of winter growing, add some tips on growing crop in winter, and introduce you to GROW’s Edible Plant Database.

My interest in food growing began when I joined the GROW Observatory last year, and gained access to a raised bed in the University of Dundee Botanic Gardens. I was an absolute novice, learning by throwing in the cheapest seeds from all the bargain shops and hoping for the best, and listening to my partner’s mother. I began in the middle of the growing season (June) in the Atlantic North (the climate of the Northern United Kingdom and Denmark), leaving little room for long season crops that year. I did two things leading up to winter that year. 1. I planted onion seeds (because the packet said I could), 2. I planted 10 cloves of garlic (because my partner’s mother told me to). This summer I was amazed to have 10 perfect bulbs of garlic, and about 15 large white onions! That got me thinking… how can I take full advantage of my plot this winter?

In colder climates, people are less inclined to think about making the most of their growing space over the winter months, but, to me, this is arguably the most exciting time. I am dreaming of spinach that doesn’t bolt, along with spring onions and broad beans ready in early spring. The heat may make it still feel like summer, but planning and planting for winter begins now!

Alliums

Alliums (including garlic and onions) are great for overwintering, as they can handle winter freezes. They are easy to grow, low maintenance, and do well in most climates. Many alliums can either be planted in the spring for a late summer/autumn harvest, or in the autumn for a spring/ early summer harvest. Get ready to plant your onion seed/sets in September/October (slightly earlier if it’s seeds). Even closer at hand, is the time to think about planting garlic. For big bulbs the following summer, it is best to plant garlic right now, in August. It is generally advisable to plant garlic sets from a garden centre rather than garlic cloves from the supermarket, as supermarket bulbs are unlikely to be of high planting quality or disease resistance. However, planting supermarket cloves will still produce bulbs.

Leafy Vegetables

I often think of leafy vegetables/salads as a summer crop, but some can provide you with fresh produce all winter. A prime example is spinach. Certain cultivars can be harvested all winter in milder areas without any protection. In less mild areas, just a cloche, cold frame, or fleece will do the job. Cold periods are ideal for spinach, as it will be much less likely to bolt. Sow your winter spinach in August/September. Other leafy veg will produce leaves through the autumn, and into the winter if protected, such as land cress, corn salad, and oriental salad leaves. These leaves also act as ground cover.

Spring cabbages take up a lot of room in your growing space, but we have lots of room in the winter, right? Planting cabbages in the autumn, for an autumn harvest will also prevent the risk of cabbage white (Pieris brassicae & Pieris rapae), a cheeky caterpillar that can decimate your cabbages if you aren’t careful. Fortunately, they are only a problem between spring and autumn. You can plant them outdoors in July/August, or start them off indoors in August to be planted out in September/October. They will be ready by May/June. Make sure you plan for the following spring, as you don’t want to need the space where the cabbages are in the early spring.

Legumes

Broad beans are easy to grow, tasty, and full of protein; what’s not to love? For a full crop of broad beans in the spring, sow them in early November for a harvest in May/ June. If your winter is particularly severe, you may need to protect your plants with a fleece or a cloche. You can harvest them as young pods to eat whole, or when they are more mature, for our more familiar broad bean. Another perk of planting broad beans, a legume, is their nitrogen fixing qualities. Nodules on their roots convert nitrogen, unusable to plants, into usable nitrogen, increasing the fertility of your soils. Why would you leave your soil bare in the winter when you could increase its fertility — and get a crop?

Introducing the GROW Edible Plant Database

After writing this article, I got thinking about the planting calendars we have been creating in GROW, used for 9 key European Environmental Zones. The aim is to use these calendars to create an edible plant database app that can be used all over Europe, to tell you when you can plant which crops in your location. These calendars aim to offer you local advice on planting and harvesting dates that are more accurate than the general dates on the back of seed packets.

I decided to look at the Atlantic north climatic region, covering The Northern UK, Denmark, Northern Germany, and the north of the Netherlands (Metzger et al 2005). I looked at the winter crops in the database (Planting dates from Aug-Feb). Included were:

  • Leaves: Rocket, spinach, tatsoi, endive, and chard, corn salad, cress, lettuce (loose leaf, lambs, and miners), and mustard
  • Radish
  • Winter peas
  • Onions
  • Garlic
  • Rhubarb
  • Shallots

This is great to have, but what about broad beans, and winter spinach? Science is wonderful, but doesn’t often benefit from local knowledge and opinions, which in an exercise like this, is absolutely crucial.

The database states that in the Atlantic North garlic should be planted between mid-November and mid-February. My partner’s mother, who has been growing for over 20 years, told me that in Scotland we should plant our garlic at the beginning of August. This allows our garlic to get a head start while it is still warm, before shutting down for the winter, and re-starting the following spring.

So let’s improve this database! Please help us with your local knowledge by providing us with the planting and harvesting dates for your winter crops using with this database:

Let’s build this together, to create a much more accurate database for you and fellow European growers to use.

Below are some useful resources I used to help with this article.

References

College of Agricultural, Consumer and Environmental Sciences, New Mexico State University, 2015, Nitrogen Fixation by Legumes, http://aces.nmsu.edu/pubs/_a/A129/, accessed: 25th July 2018-

Metzger, M.J., Bunce, R.G.H., Jongman, R.H.G. Mücher, C.A., Watkins, J.W., 2005, A climatic stratification of the environment of Europe, Global Ecology and Biogeography, 14, 549–563, available: https://www.researchgate.net/publication/40119308_A_climatic_stratification_of_the_environment_of_Europe

Oijala, L., 2013, Amazing Alliums: Decorative, Edible and Easy to Grow, http://www.organicauthority.com/organic-gardening/alliums-easy-to-grow.html, accessed: 25th July 2018

Renouf-Miller, J., 2010, Vegetables to grow in winter: a how-to, https://www.permaculture.co.uk/articles/vegetables-grow-winter-how-guide, accessed: 23rd July 2018

The Royal Horticultural Society, 2018, Onions and Shallots, https://www.rhs.org.uk/advice/profile?PID=680, accessed: 25th July 2018

The Royal Horticultural Society, 2018, Vegetables: growing for winter, https://www.rhs.org.uk/advice/profile?PID=707, accessed: 25th July 2018

The Royal Horticultural Society, 2018, How to Grow Spring Cabbages, https://www.quickcrop.co.uk/learning/plant/spring-cabbage2, accessed: 25th July 2018

Sanderson, S., n.d., Vegetables to grow outdoors in winter, available: https://www.thompson-morgan.com/top-10-winter-vegetables , accessed: 20th July 2018