Forcing Rhubarb Methods and Equipment
Rhubarb Forcers and Forcing Techniques for Rhubarb
Mar 19, 2009
Cooking with the edible stems of rhubarb requires a sweetening with sugar or honey to lift its taste. Many kitchen gardeners and cooks will agree that forcing rhubarb over the winter months, for some varieties of Rheum x cultorum, is a valuable way of getting rhubarb crowns to produce more tender and sweeter stems for eating earlier in the season. There are two main forcing techniques for rhubarb in the kitchen garden.
Forcing Techniques for Rhubarb
Forcing rhubarb can be achieved by two techniques:
- Lifting the rhubarb crown out of the ground and exposure
- Covering the rhubarb crown with a rhubarb forcer
Forcing rhubarb by lifting the crown and exposure can be done at any time when a temperature of between 15 to 17 degrees Celsius or 59 to 62 degrees Fahrenheit can be achieved for the growing season. Initial preparation for forcing by lifting is to leave the rhubarb crowns exposed after lifting from a Saturday to the following weekend's Sunday (around 8 days).
After the initial exposure the rhubarb crowns should be planted into compost-filled large pots and placed in a dark well-ventilated place with a temperature of around 16 degrees Celsius. A kitchen gardener's aftercare of the rhubarb crowns being forced by lifting includes
- keeping the medium moist during the growing season
- inspecting for pests like slugs and snails
- watching for signs of disease such as rot
The second rhubarb forcing technique is forcing rhubarb with a rhubarb forcer. This involves covering the rhubarb crown in situ. Forcing rhubarb in the ground can be started in mid to late winter onwards. There are several rhubarb forcers to buy and recycle.
Selecting a Rhubarb Forcer to Buy or Recycle
Popular choices of rhubarb forcer include contemporary tall terracotta pots with fitted terracotta lids. Recycling a large ceramic pot within your kitchen garden to cover a rhubarb crown may be trial and error for the first year and if it produces the forcing results, it's an economical choice. Forced rhubarb was achieved with a upside down ceramic pot with small hole in the bottom (or top as a forcer) shown in the image below.
Buying vintage rhubarb forcers on eBay is an option and while individual Victorian glass bell jars or individual cloches are a popular investment buy on eBay, these can not be recycled as a rhubarb forcer. Forcing rhubarb crowns in the ground requires the forcer to cover the rhubarb crown in darkness and heat up the ambient temperature and soil.
In Royal Horticultural Society Grow Your Own Veg (Mitchell Beazley, 2007), Carol Klein writes about forcing rhubarb: "For forcing in the ground, cover healthy crowns with a rhubarb forcer or large, tall pot in mid-winter. Forcing can be hastened by mounding farmyard manure or garden compost around the forcer to heat up. Once shoots appear, check them daily and harvest in two to four weeks".
Limitations of Forcing
While producing earlier sweeter and more tender edible stems of rhubarb is an attractive prospect for kitchen gardeners and cooks, a judicious use of the rhubarb crowns is best. Although rhubarb is a perennial vegetable, rhubarb crowns will strain and lose vigour if forced annually.
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