How to Grow Hyssop Seeds
Grow Guide #2393
Binomial name: Hyssopus officinalis
Life Cycle: Perennial
This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Hyssop (Hyssopus officinalis).
There are other plants that are called hyssop that are different species botanically. Anise hyssop and Hyssop- Mexican Giant (both Agastache sp.) are examples. Refer to the individual product listings for information on how to grow these species.
When to Sow Hyssop Seeds
Hyssop is a perennial plant that grows year round in most climates. Use the table below to identify the best time of year to sow hyssop seeds in your climate.
Hyssop plants are best grown in full sun. Choose a location that will receive at least 6 hours of full sun each day.
Hyssop plants are perennial, meaning they live for several years. Choose a permanent position where plants can grow undisturbed by regular digging or other disturbance.
Hyssop plants need a very well drained soil. In most cases there is no need to enrich soil with manure or other fertilisers. Prepare soil by weeding it thoroughly and digging it over to loosen it. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.
Hyssop plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 20 litres is recommended for hyssop. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.
How to Sow Hyssop Seeds
Hyssop seeds do not require any treatment (eg soaking, stratification) before sowing.
Hyssop seeds grow best when they are raised in trays or other containers and transplanted to the garden once established.
- Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
- Sow seeds 6mm deep.
- Keep soil moist but never wet or dry.
- Seeds should germinate in around 3-10 days at a soil temperature of 20-22°C.
- Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
- Plant out, spacing plants 40-60cm apart.
How to Grow Hyssop
Hyssop plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.
If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a balanced fertiliser or one formulated for fruit and vegetables can be beneficial:
- Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
- Apply liquid fertiliser at the recommended rate and frequency while plants are fruiting or flowering.
When plants have finished flowering prune them back to neaten them and encourage strong new growth. Using sharp secateurs or snips, cut individual stems just above a set of lower leaves.
How to Harvest Hyssop
Hyssop should be ready to harvest in approximately 90-95 days.
Hyssop is ready to harvest when the stems have grown long enough to pick, and can be harvested as needed. Harvest by pinching off the outer stems and leaves, leaving some on the plant for future growth. Hyssop can be stored short term in a perforated plastic bag in the fridge, or the stems can be placed in a glass or jar of water to keep them hydrated. For longer term storage, hyssop can be dried.
Common Problems when Growing Hyssop
Like all plants, hyssop is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing hyssop plants:
- Powdery mildew is caused by fungal spores reproducing on the leaves of plants. First showing as white spots on leaves, affected areas can spread quickly to cover the entire leaf surface. While rarely fatal, powdery mildew can reduce yields. Water plants at soil level (not on leaves) to prevent spreading spores, allow good air flow between plants, remove affected leaves and if necessary spray with an appropriate fungicide or homemade spray. Read more here about powdery mildew here.
- Slugs and snails are molluscs that feed on tender leaves and shoots, mostly at night, leaving slimy trails behind them. Control them by removing their hiding places, keeping free range poultry, collecting them by torchlight or by placing traps. Read more about slugs and snails here.