This low-maintenance herb belonging to the mint family produces pretty blooms and a potent fragrance that will add zest to your flower bed and zing to your kitchen recipes.
If you’ve had success growing lavender from seed, you’ll be pleased to know that the Hyssop plant enjoys similar conditions. If not – don’t fret!
We’ll cover the best-loved Hyssop seed varieties and where to find them, plus steps on seed germination, care tips, and much more
Hyssop at a Glance
Hyssopus officinalis – otherwise known as ‘Common Hyssop’ is considered to be the main variety, but you’ll come across a few plants labeled ‘Hyssop’ which can be baffling when making your selection.
These other varieties are cultivars or hybrids that hail from two different groups within the mint plant family: Hyssopus and Agastache.
Both types are evergreen perennials bearing similar foliage and narrow flower spikes, but these can vary in color, height, fragrance strength, shade tolerance, cold-hardiness, and more.
The following varieties are popular for their showy flowers and knack for attracting hummingbirds, honeybees, and butterflies:
- ‘Blue Boa’ (Anise Hyssop) – Cultivar; 2-3ft tall; dark-violet blue with deep-green foliage; sweet licorice scent; drought-tolerant; part-sun/part-shade required.
- Agastache ‘Black Adder’ (Giant Hyssop) – Hybrid cultivar; 2ft tall; reddish-violet with dark gray-green foliage; thrives in full sun/part shade; deer-resistant; susceptible to crown rot.
- ‘Rock Hyssop’ (Hyssopus officinalis s. arisatus) – Cultivar; 0.9ft tall; dark-blue with green foliage; prefers full sun; cold-hardy; prefers alkaline-neutral soil.
- Agastache ‘Bolero’ – Cultivar; 1-2ft tall; rose-purple with bronzy-green foliage; aniseed scent; prefers well-draining pH7+ soil; needs full sun.
- Agastache ‘Kudos Ambrosia’ – Hybrid; 1-2ft tall; rose-pink/pale-orange with gray-green foliage; pH 5.5-6.5 soil is preferred; drought-tolerant; requires full sun.
- ‘Korean Mint’ Hyssop (Agastache rugosa) – Cultivar; up to 5ft tall; lavender-blue with mint/licorice scent on light-green foliage; requires full sun; cold-hardy.
Best Places To Buy Hyssop Flower Seeds
Hyssop Seed Planting & Germination
- Seed tray/small pots
- Well-draining soil mix
- Misting bottle
- Soil thermometer (optional)
- Grow lights
- Heat mat
1. Fill a Seed Tray/Small Pots with Well-Draining Potting Soil and Moisten
Starting 8-10 weeks before the last frost (March-April), fill a seed tray or several 3-inch pots with indoor potting soil mix containing at least 30% perlite for drainage.
Moisten the mix lightly with a misting bottle and firm the soil lightly with your fingertips.
2. Press Seeds Lightly into the Soil & Lightly Cover with ¼-inch of Soil
If sewing in a seed tray, place each seed an inch apart from each other, gently pressing the seeds just below the soil surface. If sewing in separate pots, place 2-3 seeds per pot into the soil.
Lightly cover the seeds with a ¼-inch (5mm) of soil. Do not cover the tray/pots with lids.
3. Place the Tray/Pots in a Warm, Sunny Location
Place your seed container(s) in a sunny windowsill and supplement natural light with grow lights for at least 8 hours a day, rotating the tray daily for even growth.
Maintain a constant climate between 65-70°F with the aid of a heat mat beneath the container(s). Be careful not to overheat the soil to prevent fungal growth.
4. Keep the Soil Moist & Allow Seeds 14-21 Days to Germinate
Check the soil daily to make sure it doesn’t dry out and mist with room temperature water to avoid shocking the seeds.
Germination should occur in 14-21 days. After this period, seeds should begin sprouting around 4-10 days later
5. Remove Excess Seedlings in Pots Once they Measure 2-3 inches Tall
Once the sprouted seedlings in pots measure 2-3 inches tall, remove excess seedlings at soil level using sterile scissors so that only one seedling remains per pot.
6. Mist Seedlings Until They Measure Several Inches & Have a True Set of Leaves
Continue to moisten the soil until seedlings measure several inches tall and have developed a true set of leaves – these will be more decoratively-shaped than the rounded baby leaves, appearing more like small versions of the adult foliage.
7. Transplant Seedlings Once Outdoor Temperatures Reach 70°F Daily
Once night-time temperatures remain above freezing outside and daily temperatures are consistently 70°F+, plant your seedlings 12-18 inches apart in light, well-draining loam/sandy soil.
Choose a planting site that receives full sun for most of the day and water them well until they are established.
7 Tips for Growing Hyssop From Seed
- Use freshly-prepared/purchased potting mix – non-sterile garden soil may contain harmful organisms, risking disease.
- Keep temperatures consistent during germination to prevent seed-killing fungal spores.
- Always use sterilized containers and tools. Wipe tools with rubbing alcohol between use and either use new containers or disinfect existing ones with 1:9 household bleach and water solution.
- Maintain slightly moist soil – soggy risks rot whilst overly-dry won’t enable germination. Let your seed tray/pots drain adequately to prevent waterlogged soil.
- Opt for cool-white fluorescent grow lights. Regular incandescent lights can roast your seedlings and result in leggy, spindly growth.
- For improved air circulation, place an oscillating fan on a low setting near the seedling container(s) for 2 hours a day to ward off disease and encourage sturdier development.
- Keep a record of germination speed, sprouting time, temperatures used, issues that arose, etc for future referral!
Growing & Caring for Hyssop
Congratulations! You’ve successfully grown your hyssop seeds into proud, foliage-bearing seedlings ready to be planted outdoors.
Now comes the real nurturing – providing the best possible environment for those seedlings to flourish and produce beautiful, fragrant blooms.
Hyssops appreciate loose, rocky substrates such as loamy, sandy soils as these provide excellent drainage and will not retain too much moisture as to risk root disease. If you have impacted clay garden soil, mix in sand to loosen things up.
Though soil pH preference can vary among varieties, hyssops generally grow best in a range of 6.5 to 8.0 (slightly alkaline) so perform a soil pH test before planting. Add plenty of well-rotted compost to your planting bed to rebalance levels and act as slow-release fertilizer.
Full sun exposure is ideal, so pick a spot that receives a solid 6 hours of morning-afternoon sunshine. A south-facing bed or border will be perfect.
Hyssops luckily grow well in partial shade, so any area that gets a minimum of 4 hours strong afternoon sun will do. Warmer climates should consider utilizing a canopy or the shelter of a nearby tree to protect against heat extremes.
Watering & Fertilizing
Hyssop plants are drought-tolerant, so light, consistent watering is key. Provide an inch of water 1-2 times weekly and ensure the top inch of the soil bed is dry in between watering to avoid root issues.
As the mix of compost in the soil makes it sufficiently fertile, a one-off application of an all-purpose balanced fertilizer with a 10-10-10 NPK ratio around mid-late fall or in the spring will suffice.
Take the youngest leaves from the plant before it flowers by taking stem snippings with sterile pruning shears and stripping the leaves from the stem.
To harvest flowers, wait until the blooms are three-quarters open and take cuttings in the morning once the dew has dried for optimal flavor. Gather cuttings in bunches and hang them upside down in a dark, well-ventilated area for 5-6 days. Once dry, crush the leaves/flowers, leaving them unwashed to preserve the aromatic flavor.
Hyssop Plant & Seed Common Questions:
Is Hyssop Easy To Grow From Seed?
Hyssop is very straightforward to grow from seed, boasting an excellent germination rate of 92-98% which ensures successful sprouting in roughly 9 out of every 10 seeds sewn. They can germinate in as little as 10 days in specialized seeding medium and sprout readily in ideal temperatures and moisture levels.
How Do You Harvest Hyssop Seeds?
Once a hyssop plant flowers, allow the seed pods to brown and dry out. Take a stem cutting containing the seed pods and put it in a paper bag, placing the bag in a warm area of indirect sunlight. In 1-2 weeks, the seeds should fall from the pods. Remove the chaff and store the seeds in the bag in a cool, dark room over winter.
Does Hyssop Come Back Every Year?
Hyssop is a perennial plant that browns and dies back during winter, but while its flowers cannot survive the cold, its roots will remain stable in warm climates, allowing it to regenerate its blooms in the following year.
Should Hyssop Be Cut Back?
Once established, hyssop plants should be pruned back heavily to prevent spindly growth and promote flowering. Cut it back by 1/3 after blooming in early spring or late fall to encourage flowering the following year.