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Kalmia latifolia

Calico Bush · Clamoun · Ivybush · Mountain Laurel

Family EricaceaeGenus Kalmia

A shrub covered in pink and white cupped flowers above glossy leaves
The whole plantQwert1234CC BY-SA 3.0

About the plant

What it is and where it grows — not part of any germination protocol.

Safety

Toxicity
High severity. All parts. Andromedotoxin, a resinoid; arbutin, a glycoside, Grayanotoxins.Extension Gardener Plant Toolbox

The plant

Habit
Broadleaf evergreenPlant Finder
Habit
shrubPlants of the World Online
Height
5-15 ft1.5-4.6 mPlant Finder
Spread
5-15 ft1.5-4.6 mPlant Finder
Flower
Showy; rose to white with purple markingsPlant Finder
Blooms
MayPlant Finder
Native range
Eastern United StatesPlant Finder
Hardiness zones
4-9Plant Finder
Note
Deno warns his counts are rough: the seed is tiny and hard to separate from the crushed capsule.Seed Germination Theory and Practice, 2nd ed.

Growing conditions

Sun
Part shadePlant Finder
Soil
Cool, moist, rich, acidic, humusy, well-drainedPlant Finder
Soil pH
Acid (<6.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, Moist, Occasionally DryExtension Gardener Plant Toolbox
Watering
MediumPlant Finder

Toxicity is noted only where a source states it. No note here is not a finding of safety.

Sources: Plant Finder — Missouri Botanical Garden; Plants of the World Online — Royal Botanic Gardens, Kew; Extension Gardener Plant Toolbox — NC State Extension; Seed Germination Theory and Practice, 2nd ed. — N. C. Deno.

Worth knowing

This source reports 4 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Low Rated by us, not by the source.

Start around February 22, 2027 for a May 3 last frost.

  1. Separate the seed from its case

    Crush the hard capsule so light can reach the seed.

  2. Sow on the surface — do not cover

    Temperature: 70°F 21°C Light: light

No stated waiting before sowing. Then 42 days to germinate.

95% germination in 28–42 days.

Crush the capsule, sow on the surface, give it light. That is the entire protocol.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, KalmiaPublic domain
Show the original text
Kalmia (Ericaceae). Kalmia requires light as found by R. Jaynes for K. angustifolia, K. cuneata, K. hirsuta, K. latifolia, K. microphylla, and K. polifolia (ref. 41) and confirmed by myself for K. angustifolia and K. latifolia. In my studies it was found for K. angustifloia, and K. latifolia that a prior 3 m at 40 had no effect on percent germination, the induction time, the rate law, and the rate constant. The seed is contained in hard spherical capsules. These must be crushed to allow light to reach the seed. The seed is small and hard to separate from the hard capsules so that seed counts and percent germination are inaccurate. K. latifolia germ. 70L(95% in 4-6 w) and 70D(none). This was true for both fresh seed and seed DS 6 m at 70 or 40. A prior 3 m at 40 had no effect on the germination in 70L and promoted a small germination in 70D as shown by 40-70D(4%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Kalmia. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 2

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around December 15, 2026 for a May 3 last frost.

  1. Separate the seed from its case

    Crush the hard capsule so light can reach the seed.

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    Deno gives no length for this period; three months is his standard cycle.

  3. Warm moist stratification

    Temperature: 70°F 21°C Light: dark

about 3 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.

4% germination.

Cold buys a token 4% in the dark. In light it changes nothing at all.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, KalmiaPublic domain
Show the original text
Kalmia (Ericaceae). Kalmia requires light as found by R. Jaynes for K. angustifolia, K. cuneata, K. hirsuta, K. latifolia, K. microphylla, and K. polifolia (ref. 41) and confirmed by myself for K. angustifolia and K. latifolia. In my studies it was found for K. angustifloia, and K. latifolia that a prior 3 m at 40 had no effect on percent germination, the induction time, the rate law, and the rate constant. The seed is contained in hard spherical capsules. These must be crushed to allow light to reach the seed. The seed is small and hard to separate from the hard capsules so that seed counts and percent germination are inaccurate. K. latifolia germ. 70L(95% in 4-6 w) and 70D(none). This was true for both fresh seed and seed DS 6 m at 70 or 40. A prior 3 m at 40 had no effect on the germination in 70L and promoted a small germination in 70D as shown by 40-70D(4%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Kalmia. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 3

DerivedN. C. Deno, 1993

Difficulty Very high Rated by us, not by the source.

Start around December 15, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

about 3 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

4% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Kalmia p. 163Public domain
Show the original text
Kalmia (Ericaceae). Kalmia requires light as found by R. Jaynes for K. latifolia germ. 70L(95% in 4-6 w) and 70D(none). This was true for both fresh seed and seed DS 6 m at 70 or 40. A prior 3 m at 40 had no effect on the germination in 70L and promoted a small germination in 70D as shown by 40-70D(4%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Kalmia p. 163. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 4

DerivedN. C. Deno, 1993

  1. Separate the seed from its case

    Crush the hard capsule so light can reach the seed.

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

No stated waiting before sowing.

0% germination.

Nothing in the dark, from fresh seed or after six months' dry storage.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, KalmiaPublic domain
Show the original text
Kalmia (Ericaceae). Kalmia requires light as found by R. Jaynes for K. angustifolia, K. cuneata, K. hirsuta, K. latifolia, K. microphylla, and K. polifolia (ref. 41) and confirmed by myself for K. angustifolia and K. latifolia. In my studies it was found for K. angustifloia, and K. latifolia that a prior 3 m at 40 had no effect on percent germination, the induction time, the rate law, and the rate constant. The seed is contained in hard spherical capsules. These must be crushed to allow light to reach the seed. The seed is small and hard to separate from the hard capsules so that seed counts and percent germination are inaccurate. K. latifolia germ. 70L(95% in 4-6 w) and 70D(none). This was true for both fresh seed and seed DS 6 m at 70 or 40. A prior 3 m at 40 had no effect on the germination in 70L and promoted a small germination in 70D as shown by 40-70D(4%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Kalmia. Quoted exactly. Every value on this card comes from this record; the step names come from a fixed list.

How each step is done, in Deno’s words, and what Verified and Derived mean.

Germination trials

Readers’ own records of sowing this species, published after review. Share your trial · All trials

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