It is only within the past decade that a number of new noteworthy members of the genus Agastache have emerged from botanical obscurity and entered the gardening spotlight. There are a number of standouts that will dazzle gardeners with their copious flowers, statuesque growth habits, and amazingly long seasons of bloom.
Many of the newer selections are from the south-western United States and from Mexico. While the small-flowered species and hybrids, such as anise hyssop, attract butterflies and bees, the large-flowered varieties have co-evolved with hummingbirds as their primary pollinators and have long flowers in shades of orange, pink, lavender-pink, and rose-pink.
Each one has a scent all its own, and the aromatic foliage and flowers are appealing to bees, butterflies, hummingbirds, and gardeners alike. Best of all, they offer colour to the garden in late summer and early autumn, when many gardens are winding down and getting just a little bit dull.
The only problem with Agastache is that if you are inclined to collect plants, they’re very seductive. You start with one, and the next thing you know, you’ve got ten different Agastache in the flowerbed and are wondering where you can find space to sneak another one in.
Agastache pallidiflora subsp. neomexicana produces a continual mass of lavender-rose, scented flowers from June to September. The soft, touchable flower spikes must be one of the prettiest flowers of all this pretty family.
Also known as Rose Mint, the flowers are extremely attractive to bees and butterflies. Exceptionally long-flowering, if the flowers are dead-headed frequently, they will keep coming throughout the season. The plants grow 45 to 60cm (18 to 24in) tall, they are sturdy and upright and do not need staking. They are ideal as a border or container plant.
These easy-to-grow and easy to care for plants enjoy dry soils and sunny positions. A short-lived perennial they will flower in the same year given an early sowing and can be used as an annual.
Sow early in February-March under glass to flower September-October, or sown April-June they will flower June-September the following year.
Agastache is a ‘wonder honey plant’, it produces copious amounts of nectar for bees and butterflies to feast upon. It is an important crop for commercial honey production, it is estimated that just one acre of Agastache can support over 100 hives. Because of its later season and prolific flowering, it is a boon for building up bees’ honey reserves before winter and will produce a honey surplus where drifts are grown. The flowers produce nectar that makes a light, good-quality honey. In addition goldfinches and other small birds love the seeds in winter.
Sowing: Sow February to March or April-June.
Sow early in February-March under glass to flower September-October, or sow April-June to flower June-September the following year. Seed can also be sown directly in the ground in spring.
Sow under cover; sow in warmth to germinate; prick out and harden off in late spring. Or sow direct in autumn when soil is warm. Protect seedlings throughout winter. Likes rich moist soil and full sun.
Sow the seeds into cells or pots containing good quality seed compost. Sow finely onto the surface and press lightly into the compost, but do not cover, as light aids germination of seeds. Place in a propagator or cover with a plastic lid and place in a warm place, ideally at 18 to 20°C (65 to 68°F).
Water from the base of the tray, keeping the compost moist but not wet at all times. Germination 14 to 28 days. Once some of the seeds have germinated air should be admitted gradually otherwise the seedlings may suffer damping off.
Once the seedlings have their first pair of true leaves (they come after the seedlings first pair of leaves) and are large enough to handle, Prick out each seedling into 7.5cm (3in) pots to grow on.
Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out after all risk of frost has passed into well drained soil. Plant 30cm (12in) apart.
To prepare ordinary garden soil for planting, add 5cm (2in) of gravel and 10cm (4in) of compost. Mix in well down to 30cm (12in). Dress plants with gravel to keep water away from crown to prevent rot.
Agastache prefers free-draining soil but tolerates almost any soil and will cope with dry, poor soils very well. They can be grown in full sun but will take some shade if dry. As is typical of many aromatic perennial herbs, a 'tough love' approach works best—full sun and not too much water or fertiliser. In fact, most plants will need little, if any, supplemental irrigation. In dry climates, a deep soaking every week or two during the summer growing season is adequate.
The sturdy plants will usually not need staking, but you may need to do so if planted in rich moist soils or in exposed positions. Although agastache already boasts a very long flowering period, usually until frost, the plants will be stronger and more floriferous if you cut back flower stalks as flowers fade.
Agastache are short-lived perennials, don’t worry too much if your plant keels over after three or four years, you haven’t done anything wrong. They will self-seed where happiest, but this is usually never enough so collect the seed to ensure that you will never be without.
Remember that when different Agastache species and hybrids are planted in the same garden, they will cross-pollinate. Watch for volunteer seedlings, and weed out individual plants that don’t demonstrate desirable habit and flower colour.
A few Agastache species are not reliably hardy, especially in wet winters, but Agastache aurantiaca is one of the hardiest of the species, to around minus 18°C (0°F). Take care when mulching hyssops, especially in wetter climates. In these areas, it is best to avoid mulching materials like composted leaves, lawn clippings, and bark chips since they can encourage the growth of fungal and bacterial pathogens. Pine needles are a better choice, but a few inches of crushed-gravel mulch is ideal.
Cottage/Informal Garden, Flower Arranging, Containers, Borders and Beds.
For cut flowers, harvest when a third to half of the florets have opened.
We do only just seem to be waking up to the herbal essences of Agastache. There are, however, around a dozen different species, some of which earn their place in the herb garden better than others. All have deliciously, spicily scented leaves as well as those lovely smoky blue or purple flowers.
Take one or two and chew them and you’ll freshen your breath with its clean, savory flavour.
Pick young growth and sprinkle in salads, use to decorate cakes or float in drinks. Agastache added to your Pimms lifts it to a higher sphere altogether, or make a tea, the mintier ones, like A. rugosa, often have a better flavour, the crushed leaves smell strongly of mint or aniseed and are often likened to liquorice.
You can dry the leaves for potpourri and also flavour meat, specifically pork, with a uniquely piquant tang, either aniseedy or minty depending on the species you choose.
If you plan to collect seeds, be aware of cross-pollinating; do not place different agastache plants close together.
At the end of the season, each flower will produce four oval-shaped nutlets containing dark, tiny seeds. Allow them to dry on the stem, collect in paper bags, remember to label and sow in spring or in autumn.
The genus Agastache has about 3,500 species worldwide, many of them ornamental and economically important for their essential oils.
About 30 species are native to North America and Asia. Agastache pallidiflora subsp neomexicana is native to the American Southwest, particularly the states of New Mexico and Texas. It can be found in moist mountain forests and canyons.
The genus name is related to the flower clusters. Agastache, from the words agan, meaning ‘very much’ (or ‘many’) and stachys, ‘an ear of corn or wheat’ referring to the shape of the flower spikes, so meaning ‘having many spikes’.
The specific epithet is from Latin means 'grey-haired' or 'hoary' in reference to the grey-green leaves of this plant.
Also known as Rose Mint, it refers to the lavender-rose, scented flowers.
In the US, it can be found with a number of common names: Mountain Giant Hyssop, Bill Williams Mountain Giant-hyssop, New Mexico Giant Hyssop
Synonym: Agastache neomexicana.
- Additional Information
Packet Size 25mg Average Seed Count 40 Seeds Family Lamiaceae Genus Agastache Species pallidiflora subsp neomexicana Synonym Agastache neomexicana Common Name Rose Mint, New Mexico Giant Hyssop Other Common Names Bill Williams Mountain Giant-Hyssop, Mountain Giant-Hyssop Hardiness Hardy Perennial Hardy Down to -18°C (0°F) Flowers Bright lavender-rose, scented flowers Natural Flower Time July to October Foliage Fragrant mid-green oval leaves Height 45 to 60cm (18 to 24in) Spread 30 to 45cm (12 to 18in) Position Full sun for best flowering Soil Reasonably fertile, moisture retentive but well drained soil