Other Uses
A fine brown dye is obtained from the leaves and flower heads. An essential oil from the female fruiting heads is used in perfumery. Average yields are 0.4 - 0.5%. Extracts of the plant are used in Europe in skin creams and lotions for their alleged skin-softening properties. A fibre is obtained from the stems. Similar to hemp (Cannabis sativa) but not as strong, it is used to make a coarse kind of cloth.
It is sometimes used for filler material in corrugated paper or board products, but is unsuited for corrugated paper because of low pulp yield and high chemical requirement, or for production of high-grade pulp for speciality paper. The fibre is very durable but it is difficult to separate, the stems need to be soaked beforehand for a whole winter. A paper can also be made from the fibre; the stems are harvested in the autumn, the leaves removed and the stems steamed until the fibres can be removed. The fibre is cooked for 2 hours with lye and then hand pounded with mallets or ball milled for 2½ hours. The paper is brown in colour.
Cultivation
Easily grown in a good garden soil in sun or semi-shade. Prefers a deep rich loam and a warm sheltered position. Plants can succeed in dry shade if plenty of humus is incorporated into the soil, once established they are also somewhat drought tolerant. Hops are reported to tolerate an annual precipitation of between 31 and 137cm, an annual temperature in the range of 5.6 to 21.3°C and a pH of 4.5 to 8.2. Plants are very hardy tolerating temperatures down to about -20°c when dormant. The young shoots in spring, however, can be damaged by any more than a mild frost. A climbing plant, supporting itself by twining around the branches of other plants. Hops are frequently cultivated, both commercially and on a domestic scale, in temperate zones for their seed heads which have many medicinal qualities and are also used as a flavouring and preservative in beer.
There are many named varieties. They grow best between the latitudes of 35 - 51°N and 34 - 43°S, with mean summer temperatures of 16 - 18°C. Generally, for beer making, the unfertilized seed heads are preferred and so most male plants are weeded out. Hops are fairly deep rooted, but with a network of shallow feeding roots. These horizontal feeding roots spread out at depth of 20 - 30 cm in the soil and give rise to fibrous roots in upper layers of soil.
The vertical roots develop downwards to a depth of about 150 cm with a spread of 183 - 244 cm and have no fibrous roots. The bruised leaves are refreshingly aromatic whilst the flowers cast a pleasing scent. A food plant for many caterpillars. Dioecious. Male and female plants must be grown if seed is required.
Propagation
Seed - sow spring in a cold frame. Germination is fairly quick. Prick out the seedlings into individual pots as soon as they are large enough to handle and plant out in the summer or following spring. Division in spring as new growth begins. Very easy, you can plant the divisions straight out into their permanent positions if required. Basal cuttings in March. Harvest the shoots when they are about 10 - 15cm long with plenty of underground stem. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.
