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Agastache scrophulariifolia (Purple Giant Hyssop)

Agastache scrophulariifolia (Purple Giant Hyssop)

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Regular price $ 10.67
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$30 minimum per species for seed.

Each species requires a minimum of $30 of seed to proceed with checkout.

Pure Live Seed

Seed is provided in Pure Live Seed (PLS) unless otherwise stated.

Pure Live Seed (PLS) expresses the viable seed content of a seed lot using its purity and germination or viability test results. It helps you compare seed lots and calculate how much bulk seed is needed to meet a specified PLS planting rate.

PLS weight and bag weight

PLS weight is not the same as the total weight of seed in a bag. For example, a lot with 80% purity and 75% viability contains 60% PLS: 80 × 75 ÷ 100 = 60. Supplying 10 lb PLS from that lot requires about 16.67 lb of bulk seed.

Use the current seed test and the stated basis of the mix specification. Germination calculations may include applicable hard or dormant seed. Seed-count estimates also require the number of seeds per pound; PLS alone does not provide a seed count.

What to check when buying a mix

Check whether each rate is stated in PLS pounds, bulk pounds, or a combination. A mix with both bases should not be described as having an all-PLS total.

PLS does not remove weed seeds or guarantee establishment. Review the seed label and analysis for weed content, and match site preparation, planting conditions and follow-up management to your project.

Sources: USDA NRCS, Understanding Pure Live Seed and The Importance of Seed Quality for Natural Resource Conservation.

Weight Conversions lbs. to oz.

0.01 pounds = 0.16 ounces

  • 0.1 pounds = 1.6 ounces
  • 0.25 pounds  = 4 ounces
  • 0.5 pounds = 8 ounces
  • 0.75 pounds = 12 ounces
  • 1.00 pounds = 16 ounces

Purple giant hyssop needs a little breathing room among its neighbors. Moisture-retaining soil and partial light suit its tall stems; dry sun and dense competition are less forgiving.

For Agastache scrophulariifolia, choose partial sun to light shade and moist to mesic soil. Recorded habitats include dry to moist upland forest openings; Upland prairies; Scrubby barrens; Moist thickets. Reported height: 2½-6 ft.

Growth habit: upright perennial; short rhizomes often produce clumps of clonal plants. Allow space for this growth between neighboring plants over several seasons, rather than spacing only for the size of a young plant.

Plant specifications

Key growing facts

Sunlight Partial sun to light shade
Soil moisture Moist to mesic
Height 2½-6 ft
Bloom season Mid-summer to autumn
Show / hide ▾Growing & planting details
Growth habit Upright perennial; short rhizomes often produce clumps of clonal plants
Root form Fibrous roots; Rhizomes

Plant identification & seed reference

Botanical name Agastache scrophulariifolia
Other common names purple giant hyssop
Plant family Lamiaceae

Plant characteristics

Agastache scrophulariifolia (Purple Giant Hyssop) is a large perennial in the mint family with square stems and pale lavender flower spikes from July until fall. Reaching about six feet high, this hyssop prefers open woods and prairie situations with moist soils, although it will readily adapt to mesic and dry areas. Its long-blooming flowers are popular with bees and butterflies.

  • Flower Color Violet
  • Flower Time July-October
  • Show / hide ▾Plant communities & associatesNo verified list yet

    A species-level list has not yet been verified for this listing.

    Show / hide ▾Native range & C-value

    State nativity describes a broad range. Use the Chicago-region assessment for local context; a state listing does not establish county nativity.

    Wetland indicator — Corps Chicago 2017 table UPL
    C-value — Chicago region, Flora 2017 5
    Chicago-region native — Flora 2017 Yes
    Native range — U.S. states Connecticut; Illinois; Indiana; Iowa; Kansas; Kentucky; Maryland; Massachusetts; Minnesota; Missouri; New Jersey; New York; North Carolina; South Dakota; Tennessee; Vermont; Wisconsin
    County nativity Not yet verified; occurrence records do not establish nativity.
    Show / hide ▾Pollinators & wildlifeNo verified list yet

    No additional named relationships have been verified for this listing.

    Show / hide ▾Frequently asked questions

    What are the ideal growing conditions for Purple Giant Hyssop?
    Light: Partial sun to light shade. Soil moisture: Moist to mesic.

    Is Purple Giant Hyssop deer and herbivore resistant?
    Species-specific deer resistance has not been verified here. Even plants described as resistant may be browsed. Use physical protection where deer damage is a concern.

    When should I expect Purple Giant Hyssop to bloom?
    Typical flowering period: Mid-summer to autumn. Timing varies with location and weather.

    Show / hide ▾Sources & ecological notes

    Native range & ecological ratings: Flora of the Chicago Region (2017), via Universal FQA; Kew WCVP / Plants of the World Online; USACE Chicago FQA (2017).

    Growing conditions & other references: Illinois Wildflowers, John Hilty; Patrick Goggin: Wisconsin native plant guide, p. 75.

    Native range does not identify the origin of the seed or plants offered. Community and wildlife records apply to the locations and conditions described.

    Research notes & credits

    Range data: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew; 4 June 2026 release, accessed 7 September 2026. © The Trustees of the Royal Botanic Gardens, Kew. CC BY 3.0; selected and reformatted. Kew cannot warrant the quality or accuracy of these data. This use has no Kew endorsement.

    USACE/ERDC fqadata — Chicago Region FQA 2017. Herman, B., Sliwinski, R. & Whitaker, S. (2017), Chicago Region FQA Calculator; distributed by USACE/ERDC in fqadata under CC0. Values may differ from Flora of the Chicago Region (2017). CC0 dedication.

    Flora rating attribution: Kenneth Johnson (2018), Flora of the Chicago Region UFQA Database, following Gerould Wilhelm and Laura Rericha (2017), Flora of the Chicago Region: A Floristic and Ecological Synthesis. Individual rating facts are presented with original commentary; the calculator’s software license is not treated as a license for the underlying Flora publication.

    Growing guidance: Illinois Extension — Keeping deer out of the yard and garden. Selected facts in original wording. General deer advice is not a species resistance rating.

    Seed Shipping & Care

    There is a minimum order requirement of $30 for each seed species. Seed ships all year and typically ships within a week of an order being placed.

    We have attempted to put together some basic information regarding native seed installation, establishment, and maintenance.  We hope you find it helpful.  If you need further assistance on native seed establishment, please schedule a free consolation call here.

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    Solving a Site Problem? Get Expert Advice + Get Store Credit

    Whether you're fighting severe erosion, replacing invasive species, designing a pollinator haven, or seeding large acreage, choosing the wrong species wastes time and money. Talk 1-on-1 with a restoration ecologist to map out the exact species, plug counts, or seed mixes for your soil and goals. Book a consultation and get all or a portion credited directly back to your order.

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