Purple Giant Hyssop – Grow and Care

Purple Giant Hyssop is a herbaceous native perennial wildflower that blooms for a long time late in the season, and is good for bees and butterflies.  It has even been known to attract hummingbirds!

Contrary to its common name, the flowers on Purple Giant Hyssop appear to be more white in appearance, with only a hint or tinge of lavender.  Growing upwards of six feet tall in optimum conditions, this plant can turn any corner of your yard into a pollinator buffet!

 Purple Giant Hyssop Facts

  • The Native Range of Purple Giant Hyssop is basically in between the Missouri river and the Atlantic ocean.  So, the Eastern border of the Dakotas/Nebraska, then straight East to New England.
  • Purple Giant Hyssop attracts over 14 species of butterflies, moths, and bees, including the endangered rusty patch bumble bee.  It even will attract hummingbirds.
  • Songbirds will eat the seeds in early fall as they become available
  • The large size of Purple Giant Hyssop makes it a great choice for a border garden, or along a fence
  • Historically, Purple Giant Hyssop was used medicinally by Native Americans
  • Similar to its cousin, Anise Hyssop, leaves of Purple Giant Hyssop contain essential oils that are quite fragrant
  • Purple Giant Hyssop is listed as threatened or endangered in 4 states.


Purchase Seed

We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)

Quick Reference Table

Click on the image to see our quick reference table on growing Purple Giant Hyssop!

Physical Description – Purple Giant Hyssop

The overall plant is quite large, typically growing upwards of 5-6′ in optimum conditions.

Agastache scrophulariaefolia
A small specimen (3′) I located in some open, but partially shaded woods.

Stalk / Stem

Stalks will be medium green in color, and strong/erect.  Being a member of the mint family, the cross-section of a stem will be square or diamond shaped, having four angled corners.


Leaves of Purple Giant Hyssop are opposite, and 2″ wide by 4″ long.  The shape of the leaves will be lace-shaped to cordate, with serrated edges and coming to a sharp tip.  Just like it’s cousin Anise Hyssop, the leaves will smell like licorice when crushed.


At the end of the stalks there will be spikes of white to purple-white flowers that are 1″-6″ long (2.5 cm-15 cm).  The spike will be densely covered all around by small flowers that are 1/4″-3/8″ long (6-9 mm), and maybe 1/16″-1/8″ diameter (1.5-3 mm).

Blooming is slow, with individual flowers blooming on their own over a 6 week to 2-month period.  This helps make this plant so valuable, as it provides a nectar source for pollinators for a really long duration.

Growing Conditions

Purple Giant Hyssop grows best in full sun, but can do fine in partial shade as well.  Regarding moisture, it likes a balanced moisture for its soil that is well drained.  However, it can tolerate occasional drought and slightly moist soils too.  This plant cannot take extended droughts in sunny locations.

Natural Habitat

Purple Giant Hyssop typically grows in open meadows, somewhat open woodlands, and high-sides of flood plains.  Disturbance is often needed for this plant to do well and spread.  In general, farming has reduced the available areas for Purple Giant Hyssop making it a more rare plant to find.

How to care  for Purple Giant Hyssop

If planted in its proper locations, Purple Giant Hyssop will not require much (if any) care.  Nor will it require supplemental fertilizer.


Cut the plant back in the Spring once insects have emerged from dormancy.  May need to pull volunteer seedlings in the Spring.

How to grow Purple Giant Hyssop from seed

Establishing Purple Giant Hyssop from seed is not too difficult.  The seeds have a dormancy that needs to be broken though.  You can do this by cold/moist stratifying seeds for 2 months prior to planting.  Or, you can just winter-sow in pots, or direct sow on the ground in the fall.

Seeds of Purple Giant Hyssop need exposure to sunlight to germinate.  So, just press them into a potting soil or seed starting medium.  Keep moist, and wait for germination at some point after daytime temperatures warm up.

Garden Uses

Purple Giant Hyssop would be well at home along any border of a suburban property that received full sun and medium moisture, as it can provide good privacy during the growing season.  If planting a wildflower garden or micro-prairie, this plant could be a good choice as well.  Furthermore, a trio of Purple-Giant Hyssop plants could make a stunning island garden in the center of a regular lawn, that would bring in interesting wildlife later in the season.


This plant is a bee magnet!  The nectar-rich flowers of Purple Giant Hyssop will keep these plants buzzing for around 2 months each year.  Furthermore Purple Giant Hyssop will attract butterflies and hummingbirds.  And finally, birds will land on the stalks to pick out the seeds at the end of the season, giving your yard its own natural bird feeder.


Join our Facebook Group “Gardening With Native Plants”…for all levels of gardening enthusiasts…share, ask advice from other gardeners, enjoy this online community!




JOIN OUR FREE NEWSLETTER HERE.  Get our new content sent to your inbox. (No worries, we won’t spam you.)

Joe Foster

Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over six years. I hope to share some of my knowledge with you! Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!

Recent Posts