Like most of you, I have been very busy cleaning up my garden spaces. One of the perennials that requires old stems to be cut back in the spring are those in the genus Agastache. Members of this genus have got to be some of the most spectacular and rewarding plants to grace our Delta County gardens.
The Greek meaning of Agastache is "many spikes." Once you have seen these plants you will understand their name. These plants are commonly called hyssops, or hummingbird mints, and are in the mint family. There is one species native to eastern Asia, with the other 21 species native to southwestern North America and northern Mexico. But there are also many more selections available as well. High Country Gardens in Santa Fe sells 19 different hyssops.
Hummingbird mint plants can reach heights up to three feet but if overwatered can exceed that height. I've had single plants as tall as five feet and as wide as six feet. These plants are very water thrifty. They have angular stems characteristic of mints with tooth-edged lance-shaped leaves. Upright spikes of tubular, two-lipped flowers appear around mid-summer, with blooming lasting well into the fall. Flower colors can be white, pink, purple, mauve and orange.
But one of the main attractions of hyssops is their strong fragrance. Some have licorice fragrances while another gives off a distinct double bubble gum fragrance.
Another obvious benefit of these flowering herbaceous perennials is that they attract hummingbirds. They also will draw in hawkmoths. The most common one being the white-lined sphinx. Only long-tongued insects or birds can reach the rich nectar source in these elongated tubular flowers.
An interesting aside is that hyssop is mentioned in 11 verses of the Bible, mostly in the Old Testament. Hyssop is an herb with cleansing, medicinal and flavoring properties. Most references in the bible deal with ceremonial cleansing of people and houses. Bunches of it were used as paintbrushes to spread lamb's blood on doorposts to keep the angel of death away as told in Exodus.
In planting members of the genus Agastache, make sure the soil is fast draining and in sites of full sun. Mulching should involve only small diameter gravels to protect the crown from winter moisture. If you must fertilize, only do so in the fall with a very low nitrogen rate. If you over fertilize or over water, you can affect the winter hardiness of your plants. And some varieties are very sensitive to the winter conditions in our area.
It is imperative that you not cut back hummingbird mints in the fall. Leave the old stems from last summer's growing season on the plants. Nutrients from the stems help feed the crown and fortify it against winter cold. Wait until mid-spring to cut them back. Remove the old stems just above the tuft of green foliage growing from the crown.
I have both A. cana, Sonoran Sunset Hyssop, and A. aurantiaca, Coronado Hyssop. Hyssops are resistant to deer and rabbit browsing and are really easy to grow if you watch the soil drainage issue. Last year I potted up over 30 volunteers that seeded themselves primarily in my gravel areas. There are a few Agastache varieties available at some Delta County nurseries. I got mine from Chelsea Nursery in Clifton. You won't be disappointed if you include these beauties in your garden.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.