Agastache, also known as anise hyssop or hummingbird mint, is a perennial plant in the mint family that produces spikes of tubular flowers in summer. Many gardeners are interested in planting Agastache in their gardens to attract pollinators like hummingbirds and butterflies. A common question is whether Agastache can be planted in the fall.
The short answer is yes, Agastache can be planted in the fall in most regions. However, the exact timing and technique depends on your USDA Hardiness Zone and first expected frost date. In this article, we’ll go over everything you need to know about the ideal conditions, timing, planting method, and care for transplanting Agastache in the fall.
When to Plant Agastache in Fall by Zone
The best time to plant Agastache in the fall depends on your gardening zone. Here is an overview of when to transplant Agastache in the fall by zone:
Zones 3-4
In colder zones 3-4 where the first frost typically occurs in late September/October, the ideal time to plant Agastache is at least 6-8 weeks before your first expected frost date. This will give plants enough time to establish roots before winter dormancy.Aim to transplant Agastache in early to mid August.
Zones 5-6
In zones 5-6 with an average first frost in October/November, transplant Agastache starting in early September up until about 1 month before your first frost date. The sweet spot is mid to late September.
Zones 7-8
Warmer zones 7-8 can transplant Agastache safely from late September through October, as long as it’s at least 4 weeks before your first expected frost. Try to get plants in the ground in early to mid October.
Zones 9-10
In zones 9-10 where frost is rare, you can plant Agastache in fall any time before peak winter. Late October through November tends to be ideal.
Use your specific frost dates, not zone alone, to determine the best fall planting window. The most important thing is to allow at least 4-6 weeks of growth before cold weather arrives so roots establish.
Transplanting in Fall vs. Spring
Many gardeners wonder whether fall or spring is better for transplanting perennials like Agastache. Here are some key factors to consider:
Fall Pros
- Less transplant shock because of cooler weather
- More time to establish deep roots before summer
- Take advantage of winter moisture
- Get a head start on growth vs. spring planted
Fall Cons
- Risk of early frost damage if planted too late
- Harder to find Agastache plants in fall
- Less time for growth and establishment before winter
Spring Pros
- Wider availability of plants
- Longer growing season for establishment
- No rush for frost timing
Spring Cons
- More transplant shock in hot weather
- Must baby plants through summer heat
- Less mature plants going into winter
In general, transplanting perennials like Agastache in the fall gives them a head start by utilizing cooler temperatures and fall moisture to establish roots. However, spring planting is lower risk and avoids dealing with fall frost timing.
How to Transplant Agastache in Fall
Here are some tips for successfully transplanting Agastache in the fall:
Select a Site
Choose a planting location with:
- Full sun exposure
- Well-draining soil
- Shelter from strong winds
Morning sun with afternoon shade is also fine. Agastache thrives in loamy, sandy, or gravelly soils.
Prepare the Soil
Improve drainage and nutrient levels by mixing in:
- Compost
- Aged manure
- Peat moss
You can also till the soil. Test soil pH and amend if needed – Agastache grows best in slightly alkaline soils, between pH 6.5-7.5.
Transplant Agastache
Carefully remove plants from containers, disturbing roots as little as possible. Set them in prepared holes at the same depth as in the pot, backfilling around plants and tamping down soil gently. Space 18-24 inches apart.
Water Thoroughly
Water transplants very well at planting time. Then continue deep watering once a week if rainfall is lacking. More frequent watering is needed in extreme heat.
Add a Layer of Mulch
Spread 2-3 inches of shredded bark, leaves, straw or other organic mulch around plants. This retains moisture and insulates plant roots through winter.
Prune Back Flower Spikes
Prune off any remaining faded flower spikes down to the foliage. This encourages plants to direct energy into root growth rather than seed production.
Protect from Frost
If early frost threatens tender new transplants, protect with row cover, pine needles or other covering. Remove once frost danger has passed. Mature plants are quite cold hardy.
Caring for Newly Transplanted Agastache
Here are some tips for looking after fall-planted Agastache in their first seasons:
- Water weekly the first season if rain is lacking. Soak the entire root zone.
- Mulch plants over winter to insulate roots.
- Cut back dead foliage in late winter before new growth emerges.
- Fertilize lightly in spring as plants emerge.
- Remove spent flower spikes to encourage more blooms.
- Propagate by root cuttings or division after a few years when plants get overcrowded.
With proper planting technique and follow-up care, your fall-transplanted Agastache should flourish and expand each year!
Conclusion
Planting Agastache in the fall can be rewarding if done at the right time for your climate. Pay close attention to expected first frost dates, and allow at least 4-6 weeks between transplanting and frost for establishment. Select a sunny, well-drained spot, improve soil conditions, and take care to water and mulch new plants. With a little extra care the first season, fall-transplanted Agastache will develop strong roots and put on a vigorous growth display the following year.
