Hops, scientifically known as Humulus lupulus, are perennial climbing plants cultivated for their cone-shaped flowers. These cones contain lupulin glands, which are the source of the alpha acids and oils that contribute bitterness, aroma, and preservative qualities to beer. While most growers propagate hops using rhizomes, growing hops from seed is an alternative method often undertaken for breeding new varieties or as a gardening challenge. This approach requires patience and an understanding of the plant’s natural dormancy requirements.
Preparing Hops Seeds for Germination
Hops seeds naturally develop a protective dormancy mechanism. To successfully germinate them indoors, growers must simulate cold winter conditions through cold stratification, which breaks dormancy.
Begin by soaking the seeds in room-temperature water for approximately 24 hours to soften the outer shell. Prepare a moist medium, such as peat moss, vermiculite, or fine sand, that holds moisture without becoming saturated. Mix the soaked seeds into this medium and place the mixture inside a sealable plastic bag or container.
Place the sealed container in a refrigerator, mimicking winter temperatures (33 to 40 degrees Fahrenheit). Maintain this cold, moist environment for four to six weeks, though up to three months may be necessary for optimal results. Check the seeds weekly during stratification to ensure the medium remains damp and free of mold. If the medium appears dry, lightly mist it with water. If mold is present, remove affected seeds and move the remainder to a fresh medium. This cold exposure triggers internal changes, preparing the seed for sprouting when warm conditions return.
Starting Seeds Indoors
After cold stratification, move the seeds to a warm environment to encourage germination. Use sterile seed-starting mix in trays or small pots, providing a light and well-draining substrate. Plant the seeds shallowly, covering them with only about one-eighth to one-quarter inch of the starting mix.
Maintain the temperature consistently between 70 and 85 degrees Fahrenheit, often achieved using a warming mat beneath the trays. Provide bright, indirect light, either from a south-facing window or via supplemental grow lights placed a few inches above the soil surface.
To maintain high humidity, cover the trays with a clear plastic dome or lid. Keep the soil consistently moist but never waterlogged, as excessive dampness can lead to damping-off disease. Once seedlings emerge, typically within a few weeks, remove the humidity dome entirely to improve air circulation and prevent fungal growth.
Transitioning Seedlings Outdoors
Once the seedlings have developed their first few sets of true leaves and the threat of spring frost has passed, they must be prepared for the outdoor environment. This transition, known as hardening off, acclimates the plants to direct sunlight, wind, and fluctuating temperatures.
Start hardening off by placing the seedlings in a sheltered outdoor area, protected from strong winds and intense afternoon sun, for a few hours daily. Over seven to ten days, gradually increase their exposure to direct sun and wind. This slow introduction minimizes transplant shock when they are moved to their permanent location.
The final planting site must accommodate the hops’ vigorous growth habit. Hops thrive in full sun and require deep, well-draining soil with a pH between 6.0 and 7.5. The location should offer protection from extreme winds while maintaining sufficient airflow to deter mildew. Once hardened, transplant the seedlings into the ground, setting the root ball no deeper than it was in its container, and water deeply.
Ongoing Care and Training of Hops Plants
Hops require a substantial support system immediately after transplanting due to their rapid, climbing growth. The plant produces long, flexible stems, technically called bines, which can reach 15 to 25 feet in a single season. A robust trellis, tall poles, or heavy-gauge coir twine is necessary to manage this vertical growth.
Training the bines begins when the shoots are about one foot long. Select two or three of the most vigorous bines per plant to train, removing excess shoots at the base to focus energy. Guide the bines onto their support in a strictly clockwise direction.
Once established, plants require consistent, deep watering, especially during the first year and dry periods. Keep the soil moist but not waterlogged, often requiring one to two inches of water weekly. Hops are heavy feeders and benefit from regular applications of balanced fertilizer or well-aged compost throughout the growing season.
Maintaining a weed-free zone around the crown is important, as weeds compete for resources. Applying organic mulch helps suppress weeds, retain moisture, and regulate soil temperature. Avoid piling mulch too closely against the bines, which can trap moisture and encourage disease.
Growers should remain vigilant for common pests like the damson-hop aphid and two-spotted spider mite. Fungal diseases, particularly powdery mildew and downy mildew, are also a concern in areas with high humidity or poor air circulation. Preventative measures include promptly removing infected leaves and ensuring adequate spacing between plants.
Hops cones are typically ready for harvest in late summer or early fall (August or September). The cones are ready when they feel dry and papery, and the internal yellow lupulin glands release a strong aroma when crushed. Harvesting at maturity ensures maximum flavor and preservative quality.