Hop Gardening

Small-Scale Organic Hops Manual is available for download from Crannog Ales.The hops growing manual for small-scale and organic producers. Download PDF (26 pages, 804 KB)

Introduction

The hop (Humulus Lupulus) is a hardy, perennial plant which produces annual vines from a permanent root stock (crown). Vines may grow up to 25 feet in a single season but will die back to the crown each fall. In addition to the true roots and aerial vine, the crown also produces underground stems called rhizomes. Rhizomes resemble roots but possess numerous buds and are used for vegetative propagation. Thus propagated, all plants of a given variety are genetically identical.

Hops are dioecious, which means they have separate male and female plants. Only the female produces the flowers that are used for brewing or medicinal purposes. Male plants have no commercial value, but are used to pollinate females. Pollination stimulates higher yields by increasing cone size and seed set, but because brewers prefer seedless hops, males are only grown with other wise poor yielding female varieties. Hop seed from a pollinated female is only planted when a cross between the male and female is desired to obtain a new variety.

Hops are native to the temperate zones of the northern hemisphere. They are found wild in western Europe, Asia and certain parts of North America. Commercial hops are generally grown between the 30th and 50th parallel north or south latitude and at various altitudes. Therefore the ability to grow hops is usually not limited by your location on earth. The health of the vine is more dependent on the growers ability to provide proper growing conditions and care. Under good conditions, hops are a prolific vine, will produce from 1/2 to 2 pounds of dried flowers per plant, and will be a joy to grow and utilize.

Planting

Diagram of hops rhizomes being planted

In spring, plant hop rhizomes about three feet apart in well-drained soil. Cover the rhizomes with loamy soil and a layer of mulch.

Upon obtaining rhizomes, they should be stored in a plastic bag slightly moistened and kept in a refrigerator until you are ready to plant.

The soil should be tilled to create a weed free area. A strong support system is needed for the plant to climb on. Look for space along fences, garage, or property lines. Plant in early spring once the threat of frost is gone but no later than May. The soil should be worked into a fine, friable condition prior to planting. In cold climates you can plant rhizomes in pots and transplant in June.

Plant 1 rhizome per hill with the buds pointed up and cover with 1 inch of loose soil. Hills should be spaced at least 3 feet apart if the hills are of the same variety and 5 feet apart if they are different. The first year the hop plant requires frequent light watering.

Growth Cycle

Illustration of a hop plant

Illustration of a hop burr

In this discussion of hops, I will be referring to the female of the species. Being a perennial, the hop lays dormant during winter and is rather unaffected by freezing temperatures. The time of year when the annual vines break ground, when they flower and when they die back is very much determined by local temperature and day length. The vines will not break ground until soil temperatures have risen to the point where most spring flowers appear. A minimum of 120 frost free days are required for the hop to fully ripen a crop of flowers. Once out of the ground the vines need to be supported off of the ground. Vegetative growth continues until approximately mid-July when most hops are either past bloom or in full bloom depending up on location and variety.

Hop is dioecious, producing male and female flowers on separate plants. The commercial hop is a female plant with flowers (burrs) produced on side arms that develop along the stem. Burrs develop into hop cones, which are sometimes called hops.

At this "burr" stage the flower is approximately 1/4 inch in diameter and is composed of many florets whose styles give it a spiny appearance. This is when the flower is receptive to pollen and if males are present, wind-borne pollen will fertilize the female flower and result in a seeded female hop cone. Regardless of pollination, the styles eventually fall off and miniature petals grow which eventually result in a cone-like structure.

Most female flowers develop and ripen predominately between mid-August and mid-September depending on location, weather, and cultural practices. Commercial growers actually delay flowering by removing the earliest vines in the Spring in order to enhance regrowth and encourage a higher yield of flowers. After the flowers ripen, the vine will continue to build reserves until it totally dies back with the first freezes of Fall.

Production

Because hops can produce such a large vine in a matter of months, they will use a large amount of solar energy, water, and nutrients. It is not to say that the hop will not grow under less than optimum conditions, only that the vines will be smaller. Hops prefer full sun and rich soil, preferably light textured, well-drained soil with a pH of 6.5 - 8.0 . If drainage is a problem, small mounds can be built using surrounding top soil mixed with organic matter. Because the hop is a perennial, it's not a bad idea to dig holes about one foot deep so that some manure and other slow release organic fertilizers can be mixed with your soil and replaced into the hole. This puts the nutrients in the root zone. Rhizomes should be planted vertically with the bud pointing up or horizontally about 1" below the soil surface. First year hops have a minimal root system and require frequent short waterings much like any baby plant, but do not drown it with too much water. Mulching the soil surface with some organic matter works wonders in conserving moisture as well as helps control weeds. Once the hop is established after the first season, less frequent deep watering is best, preferably drip irrigation. Try not to soak the vine during watering, as that will sometimes encourage diseases. Each Spring apply a hearty dose of manure as a top dressing or fertilize with a balanced chemical fertilizer that is recommended for garden vegetables. Don't expect very much in growth or flowers the first year because the hop is basically establishing it's root system. Full growth and maximum crops of flowers will be achieved during the second year.

Pruning

Do not prune baby hops, let everything grow. When the young vines are about 1 foot long in more mature hops, 3-4 vines are trained clockwise per string which has been staked to the hill. It is common to run 2-3 strings per hill. Remaining weaker vine should be cut off at the ground so more energy can be focused to the trained vines. Hops mainly grow vertically, but lateral sidearms extend from the main vine and produce flowers. The main concern is to support the vines and prevent sidearms from tangling. Most cones are produced on the upper part of the plant.

In July, the lowest 4 feet of foliage and lateral branches can be removed to aid in air circulation and reduce disease development. The removal of lower leaves (stripping) must be done carefully to avoid breaking or kinking the main stem. In August allow additional bottom growth to remain to promote hardiness of the crown and the plant vigor for next year.

At the end of the season you can bury healthy bottom vines for propagating new plants the next spring. Simply bury the vines in a shallow trench and mark their location. In spring dig them up and cut them into pieces about 4 inches long. Make sure each new cutting has an eye or bud.

Spacing and Support

United States-style hop growing setup

United States-style hop growing setup.

Home garden hop growing setup

Home garden hop growing setup.

Space between plants varies from country to country and is mainly based on the need to have enough room to allow tractors to get between the rows. In the United States, hops are grown on 7' by 7' grid with an 18 foot tall trellis. In a home garden, the main concern is just to get the vines off the ground and possible to keep different varieties from getting tangled up with each other. Plant mixed varieties at least 5 ft. apart. Identical varieties can be as close as 3 ft. if you don't have much room. Hops mainly grow up if they can, then lateral siderarms extend off of the main vine. Hops don't have to be grown on an 18' trellis. Some of the less vigorous varieties will yield more if they are limited to 10' - 15'.

Actually just about anything over 6 feet will work, the vine will just become bushier. The vines are easiest to grow and deal with if they are trained onto strong twine. This twine can be supported by a trellis wire, pole, tree branch or building. Small diameter poles, lattice and chain link fence also work but require more hand labor. Keep in mind that the vine does die back each Fall. In the First year vines can be established with a 6 foot stake.

Commercial hop farmers do not train up the first shoots of spring but prune them off mechanically. Hardier shoots are trained onto the string about 4 weeks later (early to mid-May in Oregon). Only 2-3 vines should be trained onto each string with 2 strings per plant. All subsequent vines, which can be extensive with older plants should be cut off. Vines are ready to be trained when they are about 12" long and must be gently wrapped clockwise onto the string without kinking. Once trained, the vine will take care of itself unless you want the vine to grow horizontally, this must be done manually.

19th century trellis

19th century low trellis

As early as the 19th century a low trellis had been developed. constructed of iron cross pieces, old gas pipes and wood. it was almost 2 meters (6' 6") high and had good wind resistance, but never became popular.

Source: Hop Cultivation in Hallertau, by I. Kettner Mainburg, 1976 p. 134

Harvest

Because most hops are produced out of reach from the ground, it is safest to lower the vines in order to pick the hops. The harvest date varies with variety and location but will become evident as you gain experience as a hop grower. At maturity, the hop aroma is at its strongest and is measured by crushing a cone and smelling it. The yellow lupulin glands in the cone become much more evident and plump looking when magnified.

The cone will develop a drier, papery feel and in some varieties a lighter color as it matures. Some browning of the lower bracts is a good sign of ripeness. Squeeze the cones as they develop and you will notice they become more light and resilient rather than green and hard. The actual picking is self-explanatory and this is where you want the flower cones, not the leaves. I don't know why raw hop cones are occasionally called leaf hops, when the idea is to not pick the leaves.

Drying

19th century storage

19th century storage
Image courtesy of The Hop Atlas 1994 by Heinrick J. Barth

Turn of the century drying kilns

Turn of the century drying kilns
Image courtesy of The Hop Atlas 1994 by Heinrick J. Barth

Drying can be done in a good dehydrator, custom made hop dryer, well vented oven, or they can be air dried. If you use heat, the temperature should not exceed 140 degrees F. Cooler temperatures take longer but a higher quality hop is obtained. Under dry weather conditions, I suggest taking a screen off of your house and setting it up in a wind protected area, elevated on each end. Spread the hops as shallow as possible and fluff daily so moist inner cones are brought to the outside of the pile. If weather is dry and the pile is not too thick they will dry in about three days.

A high moisture content in the cones will adversely affect storability and recipe formulation. The hops are dry when the inner stem of the cone (strig) is brittle and breaks rather than bends. The strig takes much longer to dry than the bracts, so be patient. Pack the hops in an air tight container and store in a freezer until used.

Diseases and Pests

Hop Twine (Coir Yarn)

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Please note: Most of the pests and diseases have humuli in the Latin name. This means that they are specific problems on hops and do not infect or inhabit other plants. Therefore if hops do not have a history of growing near your location, these problems will hopefully not exist in your area. Don't let the potential problems of growing hops stop you anymore than the potential of brewing a bad batch of beer. Mainly because of the higher heat used in drying commercial hops, the full aromatic potential may be somewhat diminished. Therefore by using lower drying temperatures and hopefully organic growing conditions, homegrown hops are the best.

Insect and Disease Damage Symptoms: a complete description of nutrient deficiencies.