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Hop (plant)

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Hops are the female flowers of the Hop vine (Humulus lupulus) used as a flavoring and stability agent in beer. The hop plant is technically a bine; unlike a vine which uses tendrils, suckers, and other appendages to aid in climbing, bines have stout stems with stiff hairs with which they climb.



The hop plant grows from a cold-hardy perennial rhizome. Shoots emerge in early spring with the first spring flowers. Hop shoots grow very rapidly and at the peak of growth can grow upwards of a foot (300 mm) a week. Hop bines climb by wrapping clockwise around anything within reach. Typically individual bines grow between 18 and 30 feet (5.5 to 9 m) depending on what is available to grow on. When the hop bines run out of material to climb horizontal shoots grow from between the leaves of the main stem and the stem.

The stem that arises from the rhizome every year is of a twining nature, reaching a great length, and is flexible and very tough, angled and prickly, with a tenacious fibre that has been used in some cases to make cloth and paper. The dark green leaves are heart-shaped and lobed, on foot-stalks, and generally placed opposite one another on the stem, though sometimes the upper leaves are arranged singly on the stem, springing from alternate sides. The leaf margins (edges) are finely-toothed.

Hops and beer

Hop acids have a mild antibiotic effect against Gram-positive bacteria, and favors the exclusive activity of brewing yeast in the fermentation of beer. The flavor imparted by hops varies greatly by variety and use: hops boiled with the beer ("bittering hops") produce a bitterness while hops added to beer later impart some degree of "hop flavor" (final 10 minutes of boil) and "hop aroma" (final 3 minutes, or less of boil) and a lesser degree of bitterness. Adding hops after the boil, a process known as "dry hopping", adds very little bitterness. The degree of bitterness imparted by hops depends on the degree to which otherwise insoluble alpha acids (AAs) are isomerized during the boil. Unboiled hops are only mildly bitter. The bitterness impact of a given amount of hops is specified in International Bitterness Units.

Noble hops are low in bitterness and high in aroma, and traditionally consist of four central European varieties:

  • Hallertauer Mittelfrueh,
  • Tettnanger,
  • Spalter,
  • and Saaz.

They contain high amounts of the hop oil humulene and low amounts of alpha acid cohumulone , and impart an elegant, refined taste and aroma to beers containing them. They are traditionally an important element of true Pilsener.

Other hops with high ratios of hop oil to bittering acids can be used as equivalents. Examples of such hops include Fuggle, Golding, Hersbruck, and Styrian.

Flavors and aromas are described appreciatively using terms including: grassy, floral, citrusy, and spicy. Most of the common commercial lager-style beers have fairly low hop influence, true Pilseners should have noticeable noble hop aroma, while certain ales can have high levels of bitterness.

The first documented instance of hop cultivation is 736 in the Hallertau region of present-day Germany, but the first mention of the use of hops in brewing is in 1079. Hops were introduced to British beers in the early 1500s and hop cultivation was begun in the United States in 1629.

In Britain today, the principal centres for production are in Kent (whence come Kent Golding hops) and Worcestershire. The principal centre for production in the United States is Washington state.

Herbal use

Hop has a mild sedative effect. Dried female buds are known to have high content of methylbutenol , which has a calming effect on the central nervous system. Possible uses are for insomnia, tensions and anxiety. If one has trouble getting sleep, hop tea before going to bed may help. Hops' antibacterial qualities stimulate gastric juice production. The medically active ingredients in Hops are humulene and lupulene .

Other uses

The hop shoots, which are only available for about three weeks in spring, were mainly eaten by the poor in medieval times. Only recently have they been rediscovered as a rare and expensive delicacy in parts of Germany. They are served raw with vinaigrette, boiled with fresh herbs or fried in batter.


The common hop, Humulus lupulus, is propagated either by nursery plants or by cuttings. These are set in hills, formed by digging holes in the spring, which are filled with fine mould, and the number of which varies from 800 to 1,000, or 1,200 holes per acre (5, 4 or 3 m²/ hole). One, two, or three plants are put in each hill; but, if hops are designed to be raised from cuttings, four or five of these, from three to four inches (75 to 100 mm) in length, are planted and covered one inch (25 mm) deep with fine mould.

At the end of the first year it becomes necessary to put poles into the hills, round which the bines reared from plants are wound; at the expiration of the second year, full-sized poles, from 15 to 20 feet, are set (though the hop-bines will run to the height of 50 feet) in the proportion of two poles to each hill, and a similar number of hop-plants are fastened loosely round each pole, by means of withered rushes. Hops begin to flower about the latter end of June or the beginning of July. The poles are now entirely covered with verdure, and the pendent flowers appear in clusters and light festoons. The hops, which are the scaly seed-vessels of the female plants, are, when the seed is formed around the end of August, picked off by women and children; for this purpose the poles are taken up with the plants clinging to them. The seeds are then dried over a charcoal fire, exposed to the air for a few days, and packed in sacks and sent to market.

The culture of hops, though profitable when it succeeds, is very precarious: as soon as the plant appears above ground, it is attacked by an insect somewhat similar to the Turnip-fly , which devours the young heads. Hop-gardens, situated on chalky soils, are peculiarly subject to its depredations. In the months of June and July, the hops are liable to be blown by a species of Aphis, or fly. This insect, however, does not endanger the growth of the plant, unless it is in a weak state, in consequence of the depredations committed on its root by the larvae of the ottermoth, Phalaena humuli. The roots are also a well-known target for the larvae of the Ghost Moth, Hepialus humuli. The foliage is sometimes eaten by the larva of another moth, the Currant Pug.

The hop is a most valuable plant: in its wild state it is relished by cows, horses, goats, sheep, and swine. When cultivated, its young tops are eaten, early in the spring, as substitutes for asparagus, being wholesome and aperient. Its principal use, however, is in brewing malt liquors, communicating that fine bitter flavour to our beer, and making it keep for a longer time than it otherwise would do. Hops also serve some important purposes in medicine.

from the Household Cyclopedia

The following information of from the 1881 Household Cyclopedia.

The hop is planted on various soils, and chiefly in valleys. Hops are generally of the best quality from strong clay land. The crop, however, is there very precarious. Those on peat are much more productive, but are liable to be affected by mold in some seasons, which reduces their value considerably. The best plantations are on a deep, loamy soil, where the produce of the latter and the quality of the former are sometimes obtained. Those which are grown on sandy and gravelly lands are seldom remarkable for either great produce or superior quality.

The plant is extremely liable to disasters from its first putting up in the spring until the time of picking the crop, which is in September. Snails or slugs, ants and flies, are formidable enemies in the first instance. Frosts are inimical to its growth, and the vines are frequently blighted even after they have reached the top of the poles. Small green flies and other insects which make their appearance in the months of May and June, when the wind is about northeast, often greatly injure them, and they are subject to take damage by high winds from the southwest. The best situation for a plantation, therefore, is a southern aspect, well shaded on three sides either by hills or planting, which is supposed to be the chief protection that can be given them.

In the winter time provide the soil and manure for the hop-ground against the following spring. If the dung be rotten, mix it with two or three parts of common earth, and let it incorporate together till there is occasion to make use of it in making the hop-hills; but if it be new dung, then let it be mixed as before till the spring in the next year, for new dung is very injurious to hops. Hops require to be planted in a situation so open that the air may freely pass round and between them to dry up and dissipate the moisture, which often destroys the middle of large plantations, while the outsides remain unhurt.

The hills should be eight or nine feet asunder. If the ground be intended to be ploughed with horses between the hills, it will be best to plant them in squares, chequer wise; but if the ground is so small that it may be done with the breast-plough or spade, the holes should be ranged in a quincunx form. Which way so ever is made use of, a stake should be stuck down at each of the places where the hills are to be made.

Be very particular in the choice of the plants as to kind, for if the hop-garden be planted with a mixture of several sorts of hops that ripen at several times, it will cause much trouble and great detriment.

The two best sorts are the white and the gray bind; the latter is a large, square hop, more hardy, bears more abundantly, but ripens later than the former. There is another sort of the white bind, which ripens a week or ten days before the common, but this is a tenderer and a less plentiful bearer, though it has this advantage, that it comes first to market. If there be a sort of hop you value, and would wish to increase, the superfluous binds may be laid down when the hops are tied, cutting off the tops and burying them in the hill, or when the hops are dressed all the cuttings may be saved, for almost every part will grow and become a good set the next spring.

English planters approve the months of October and March. The most usual time of procuring the cuttings is in March, when the hops are out and dressed. As to the manner of planting the sets, there should be five good sets planted in every hill, one in the middle, and the rest round about, sloping. Let them be pressed close with the hand and covered with fine earth; a stick should be placed on each side of the hill to secure it.


  • Lee W. Janson, Ph.D.; Brew Chem 101; Storey Publishing; ISBN 0-88266-940-0 (paperback, 1996)

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Last updated: 10-13-2005 04:56:59
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