Last Updated on October 19, 2023 by Plant Mom Care
Agastache is a herbaceous perennial consisting of over 22 different types of attractive herbs and is prized for luring pollinators to gardens.
Hummingbird mint (or Agastache cana), the commonly grown variety, is tolerant of drought and heat in arid areas and is suitable to grow in xeriscape gardens that use little or no water other than rainfall.
Other varieties prefer temperate conditions, so you might have to do some research on the different varieties to see what best suits your area.
Their heights vary according to variety, largely 3 – 5 feet high. Added to being beneficial plants in gardens, they are also beautiful, producing flowers with vivid colors from blue, light pink, deep purple, red, white, and orange with a minty fragrance.
The flowering season is fairly long, lasting for several weeks during summer. They are rabbit- and deer-resistant and attract bees, hummingbirds, and butterflies.
Light Requirements
These plants like full sun and easily tolerate hot sun during the day, so remember this when you decide where to plant them.
Watering
While they enjoy deep watering, constantly moist situations do not suit these drought-tolerant plants, particularly established ones. Only germination and seedlings need moist soil. Once established, they can go for weeks without watering.
Plan your watering routine to copy desert settings – occasional heavy rain followed by days with no water.
Humidity
Humidity isn’t good for these plants and growing them in constantly moist conditions will likely cause root rot and leaves to turn yellow. Make sure to keep the roots dry in winter, particularly in zones 5 to 6.
Temperature
Night temperatures of 50 – 55°F and daytime temperatures of 70 – 75°F are perfect for these plants. Plants will suffer damage in temperatures over 86°F.
They can tolerate temperatures of 20°F without foliar damage but are not hardy in areas where temperatures drop below that. They grow well in zones 4 to 10.
Soil
These plants grow best in soils containing low nutrient levels. Adding sand to the soil will suit these plants.
Repotting
Repot the plant after it doubles its size or once a year — whichever happens first. By this time it has probably used up the nutrients in the soil.
Even healthy plants eventually lose vigor and decline. They have to be divided every 3 – 5 years when growth and flowering start declining.
This is better done in spring or autumn in areas with mild winters. Water the plant thoroughly the night before, then lift and divide it. Prepare larger pots filled with suitable soil and transfer the divided segments. Some gardeners recommend pruning down the entire plant before repotting or dividing it.
Propagation
Propagation from seeds
Plant the seeds about six weeks before your area’s last frost, usually around February or early March. Prepare several small pots filled with moist seed starting mix and sow the seeds.
Maintain soil moisture with temperatures of 55°F. Once the seedlings grow about 4 inches high, they can be transplanted either into larger containers or in the garden, maintaining a space of 12 inches between each seedling.
Propagation by cuttings
Some varieties are propagated by cuttings. Starting plants from cuttings or division produces plants true to their parent plant. This plant can be propagated from either softwood or semi-hardwood stems.
Take cuttings just before it is about to flower and full of new growth. The ideal cuttings are those having mature and emerging leaves. Take cuttings near the crown to maintain the appearance of the parent.
Once you’ve taken the cuttings, insert the ends in rooting powder and plant them in pots filled with seed-starting mix. Maintain moisture and temperatures of 68 – 75°F to promote rooting.
This takes about 10 days. Once the roots have developed and new foliar growth emerges, the new plants can be transplanted into larger containers or in the garden
Propagation by division
The division is also necessary for keeping the plant healthy. The best time for dividing the plant is in spring when cool temperatures will prevent the roots from stress from the afternoon’s heat. This enables the divided plants to settle down before summer.
Dig the entire plant up and split the clump in half or quarters by hand. Make sure each section has enough roots to establish. You can encourage this by watering them immediately when planting and until new growth emerges.
Remember that potted plants dry faster but be careful you don’t overwater during and after propagation – keep the soil moist but not water-logged.
Additional Care
These plants don’t require feeding but top dress the soil with compost in autumn to keep them healthy.
It is important not to cut back the plants in autumn as this improves winter hardiness. Nutrients from the stems will help feed the crown and strengthen it against the cold winter.
Wait until a month or so before the last predicted frost to cut the plants down, removing old stems above the new foliage, around 4 – 5 inches above the ground.
Common Problems
These plants can be attacked by pests like aphids, spider mites, whitefly, thrips, and slugs. Spray the plants with insecticidal soap or neem oil solution to control and eradicate insect pests.
Handpick slugs at night if possible or make a hole in the soil and place a large bowl or cup with steep sides so the slugs can’t crawl out and fill it with beer (about ¾ full).
The drowned slugs can be disposed of in the morning. Keep the area around the plants free from plant debris to prevent pests from hiding there.
A few fungal diseases like botrytis, downy mildew, leaf blight, and powdery mildew can also attack the plants, particularly in humid or cool wet conditions.
Remove infected foliage, avoid watering in the evening, don’t get water on the leaves, and make sure the plants have adequate air circulation. Treat the plants with suitable fungicides. Proper care and maintenance will prevent pest infestation and disease.
Does Agastache return every year?
This perennial consistently returns every year in warm climates.
How many years does Agastache live?
This plant is known to be a short-lived perennial. In cold climates, it can last 1-3 years, but it can self-sow easily and will keep coming back for many years. Generally, it is a consistent perennial in warm climates – however, it starts declining after 3 – 5 years and can be rejuvenated by dividing and replanting.
Do you cut back Agastache in winter?
This plant becomes dormant in winter, with the stems dying back in autumn. Cut the stems down to around half their size to protect the plant from winter winds, later cutting the stems down to the ground level in early spring before plants break out from dormancy.
When should I cut back Agastache?
In cool winters, cut the stems down to half their size in autumn, later cutting the stems down to the ground level in early spring before plants break out from dormancy. Pinching off new growth in spring will promote bushy growth. If it grows as a perennial in warm climates, don’t deadhead or prune after midsummer.