Deno’s Garden

Rhododendron catawbiense

Genus Rhododendron

This source reports three treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Low Rated by us, not by the source.

Start around March 15, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: light

No stated waiting before sowing. Then 21 days to germinate.

80% germination in 7–21 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Rhododendron p. 204Public domain
Show the original text
Rhododendron (Ericaceae). Usually light was required for germination. A. catawbiense hybrids germ. 70L(80-85% in 1-3 w) and less in 70D(5-25%) or 40-70D(15%). A prior 3 m at 40 had little effect. Outdoor treatment ultimately germ. 73%, but germination extended from May to August and is inconvenient. Fresh seed and seed DS 6 m at 70 or 40 gave identical results in all treatments.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Rhododendron p. 204. 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 September 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 16, 2026.

  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 6 months from start to sowing. Germination time not stated; 21 days assumed.

15% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Rhododendron p. 204Public domain
Show the original text
Rhododendron (Ericaceae). Usually light was required for germination. A. catawbiense hybrids germ. 70L(80-85% in 1-3 w) and less in 70D(5-25%) or 40-70D(15%). A prior 3 m at 40 had little effect. Outdoor treatment ultimately germ. 73%, but germination extended from May to August and is inconvenient. Fresh seed and seed DS 6 m at 70 or 40 gave identical results in all treatments.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Rhododendron p. 204. 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 March 15, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: dark

No stated waiting before sowing. Germination time not stated; 21 days assumed.

5% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Rhododendron p. 204Public domain
Show the original text
Rhododendron (Ericaceae). Usually light was required for germination. A. catawbiense hybrids germ. 70L(80-85% in 1-3 w) and less in 70D(5-25%) or 40-70D(15%). A prior 3 m at 40 had little effect. Outdoor treatment ultimately germ. 73%, but germination extended from May to August and is inconvenient. Fresh seed and seed DS 6 m at 70 or 40 gave identical results in all treatments.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Rhododendron p. 204. 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.