Grow in the dark

WINTER months in the kitchen garden can be a little challenging due to the cold temperatures; however, some plants can be given a head start by persuading them to grow in the dark, producing early crops known as “forced”. Forced crops can be a real treat through the winter months when there is very little in the ground.

Yorkshire is well known for the famous Rhubarb Triangle, situated between Leeds, Wakefield and Bradford. In 1877, rhubarb began to be grown in Yorkshire. The Whitwell family in Leeds were the first large-scale growers in Yorkshire. Their activities eventually damaged the large London growers as more people started growing rhubarb commercially in Yorkshire. By the end of the 19th Century, “forcing” was a big business in the UK and large sheds were erected so rhubarb could be grown out of season.

If the weather conditions are right, rhubarb stems – also known as “sticks” – can be harvested from mid-spring right through to the middle of summer. However, the advantages of forcing mean you will get an earlier crop, within four to six weeks, often a month earlier than unforced rhubarb. Forcing also produces sweet and tender sticks because you are excluding light which prevents chlorophyll forming, gives a bitter taste.

Forcing plants is very easy to do. Covering the plant or bringing it indoors to warmer temperatures means growth can be simulated during the winter months.

Commercially-grown rhubarb is usually grown outside for two years to let the plant establish before digging the root known as the “crown” and bringing it inside to force it. At the end of the season they are usually composted. Most gardeners will not want to lose their rhubarb after two years, so they leave the plant in the ground and cover the crown with a large pot, plastic dustbin, or a traditional terracotta pot. Forcing does weaken the plants, making them susceptible to diseases, so should only be done during alternate years. Ideally, you should grow a couple of plants in your garden so you can alternate which ones you force each year.

Forcing other vegetables

Like rhubarb, chicory can be forced. Chicory is a great vegetable which is very popular in Italy. Forced chicory produces fresh, crisp salad leaves when there is very little available to harvest in the garden. There are many varieties available but my favourite is the “Brussels Witloof”. In the winter months, cut down the remaining leaves, leaving 2.5cm of growth; don’t cut any lower or you may remove the growth point. Dig the plant up and place in a pot,then cover with a plastic pot to block out the light and put it in cool but frost-free place.

Sea kale is another good crop to force. Leave the leaves to die back in winter, then dig the roots for early forcing and put in a warm place. Alternatively, they can be left until spring and forced where the plant is planted, covering with a large pot. After being forced, and when all the leaves and stems have been cut, remove the pot and let the new shoots grow for the remainder of the summer.

There are many more vegetables that can be forced so why not come along to RHS Garden Harlow Carr to get some more advice on how to do it.

Jobs to do this week

Sow some vegetables under cover such as chilli peppers, aubergines and tomatoes

Finish pruning your fruit trees, apples and pears

Chit potato tubers

As long as the ground isn’t frozen, continue preparing your vegetable seed beds

DIARY DATES

March 25 to April 10: Garden Detectives hunt for the Lindt Gold Bunny

Become a Garden Detective at RHS Garden Harlow Carr in Harrogate this Easter. Put your detective skills to the test on a daily garden hunt for the Lindt Gold Bunny – you may be rewarded with a chocolate treat. From Good Friday to Easter Monday, visitors can meet real fluffy bunnies and the Easter Bunny himself will be hoping round the garden from 11am to 2pm. Other activities vary daily and include: a bird of prey display and flying show, storytelling and craft workshops. Visit rhs.org.uk/harlowcarr/whatson for full details. Normal garden admission applies.