Forcing is the
horticultural
Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
practice of bringing a cultivated
plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...
into active growth outside of its natural growing season. Plants do not produce new growth or flowers (and hence fruit) during the winter, and many species only produce flowers or fruit for a very limited period. Forcing allows horticulturalists to produce these flowers and fruits at other times. This can be accomplished by cultural, physical, or chemical means, and is typically done to produce out-of-season
flowers
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
or
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
for display, consumption or sale. Forcing allows the more predictable production of products for sale, and can improve the quality of the products in some cases.
Plants respond to different types of cues to break dormancy. Forcing usually involves manipulating the temperature of the plants. Forcing a certain plant may mean it needs a certain amount of time experiencing very cold weather, or experiencing hot weather prior to cold weather. They may also need to have a wet period or a dry period separately from or in conjunction with those temperature fluctuations. For example, exposing the dormant roots of some geophytic plants, such as
tulips
Tulips (''Tulipa'') are a genus of spring-blooming perennial herbaceous bulbiferous geophytes (having bulbs as storage organs). The flowers are usually large, showy and brightly coloured, generally red, pink, yellow, or white (usually in warm ...
, to a combination of cold temperatures and moisture immediately prior to warm temperatures is an effective method of forcing them into flower. Exposing woody plants, such as fruit trees, to warmer conditions than are normal in the area--such as growing them in a warm
microclimate
A microclimate (or micro-climate) is a local set of atmospheric conditions that differ from those in the surrounding areas, often with a slight difference but sometimes with a substantial one. The term may refer to areas as small as a few squ ...
--forces them to flower and fruit earlier than usual.
Cuttings taken in the fall can be moved indoors to force them into bud break.
Pruning during the growing season is an effective way to force some plants, such as
asparagus
Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus ''Asparagus''. Its young shoots are used as a spring vegetable.
It was once classified in ...
, which are grown for their new shoots.
Forcing as a horticultural technique has been recorded as early as 1608. Historically, rotting manure was used to create
hotbed
A hotbed is a biological term for an area of decaying organic matter that is warmer than its surroundings. The heat gradient is generated by the decomposition of organic substituents within the pile by microorganism metabolization.
A hotbed cove ...
s which would provide warmer temperatures, allowing some or all of a farmer or gardener's crop to ripen earlier than it would in the open air.
Cold frames and
greenhouses
A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These s ...
are also methods of warming plants in order to force them.
Greenhouses
A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These s ...
that were used specifically for growing off-season plants were sometimes known as forcing houses.
In the
Rhubarb Triangle
The Rhubarb Triangle is a area of West Yorkshire, England between Wakefield, Morley and Rothwell famous for producing early forced rhubarb. It includes Kirkhamgate, East Ardsley, Stanley, Lofthouse and Carlton. The Rhubarb Triangle was origi ...
area of
West Yorkshire
West Yorkshire is a metropolitan and ceremonial county in the Yorkshire and Humber Region of England. It is an inland and upland county having eastward-draining valleys while taking in the moors of the Pennines. West Yorkshire came into exi ...
, England, forced
rhubarb
Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of ''Rheum'' in the family Polygonaceae, which are cooked and used for food. The whole plant – a herbaceous perennial growing from short, thick rhizo ...
is commercially grown in dark sheds and harvested by
candle
A candle is an ignitable wick embedded in wax, or another flammable solid substance such as tallow, that provides light, and in some cases, a fragrance. A candle can also provide heat or a method of keeping time.
A person who makes candles i ...
light. The name "Yorkshire Forced Rhubarb" was granted
Protected Designation of Origin
The protected designation of origin (PDO) is a type of geographical indication of the European Union and the United Kingdom aimed at preserving the designations of origin of food-related products. The designation was created in 1992 and its main ...
(PDO) status by the
European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
in 2010.
Rhubarb plants can also be grown under a
rhubarb forcer, traditionally a ceramic pot which excludes the light.
See also
*
Blanching (horticulture)
Blanching is a technique used in vegetable growing. Young shoots of a plant are covered to exclude light to prevent photosynthesis and the production of chlorophyll, and thus remain pale in color. Different methods used include covering with soil ...
*
Vernalization
Vernalization (from Latin ''vernus'', "of the spring") is the induction of a plant's flowering process by exposure to the prolonged cold of winter, or by an artificial equivalent. After vernalization, plants have acquired the ability to flower, ...
*
Houseplant
A houseplant, sometimes known as a pot plant, potted plant, or an indoor plant, is an ornamental plant that is grown indoors. As such, they are found in places like residences and offices, mainly for decorative purposes. Common houseplants are us ...
References
Horticultural techniques
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