Deno’s GardenMy Garden

Cotoneaster horizontalis

Purple-flowered Cotoneaster · Rockspray · Rockspray Cotoneaster

Family RosaceaeGenus Cotoneaster

A low spreading shrub smothered in small scarlet berries, with tiny dark green leaves along herringbone branches.
FruitAbrahamCC BY 4.0

About the plant

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

The plant

Habit
Ground Cover, ShrubExtension Gardener Plant Toolbox
Habit
subshrub or shrubPlants of the World Online
Height
2-3 ft60-90 cmExtension Gardener Plant Toolbox
Spread
6-8 ft1.8-2.4 mExtension Gardener Plant Toolbox
Flower
Pink, WhiteExtension Gardener Plant Toolbox
Blooms
SpringPLANTS Database
Native range
China North-Central, China South-Central, China Southeast, TaiwanGBIF Backbone Taxonomy
Hardiness zones
5-7Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
Clay, Loam (Silt), SandExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0), Alkaline (>8.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, MoistExtension Gardener Plant Toolbox
Watering
Drought tolerance: MediumPLANTS Database

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

Sources: Extension Gardener Plant Toolbox — NC State Extension; Plants of the World Online — Royal Botanic Gardens, Kew; PLANTS Database — USDA NRCS; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

This source reports 6 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Moderate 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. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Temperature: 40°F 4°C

about 6 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

55% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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 Moderate Rated by us, not by the source.

Start around June 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 18, 2026.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  3. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 9 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.

55% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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 High Rated by us, not by the source.

Start around March 21, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 20, 2026.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    9 germinated in this phase.

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    9 germinated in this phase.

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 12 months from start to step 4. Germination happens during step 4; time not stated, 21 days assumed.

55% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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

Difficulty High Rated by us, not by the source.

Start around December 21, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 20, 2025.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  5. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

about 15 months from start to step 5. Germination happens during step 5; time not stated, 21 days assumed.

55% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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 5

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around October 6, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on October 5, 2026.

  1. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  3. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 6 months from start to step 3. Germination happens during step 3, in 2 days.

50% germination in 2 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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 6

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around June 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 18, 2026.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    20 germinated in this phase.

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  5. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    5 germinated in this phase.

  6. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  7. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  8. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

Steps after step 4 run on after germination.

about 9 months from start to step 4. Germination happens during step 4; time not stated, 21 days assumed.

40% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Cotoneaster p. 126Public domain
Show the original text
Cotoneaster (Rosaceae). C. horizontalis germ. 70-40-70(50% in 2nd d) and 40(20%)-70-40-70(40%)- 40(5%)-70-40-70. Seed DS 6 m at 70 germ. 70(9%)-40(9%)-70(55%) and 40(55%). Seed DS 6 m at 40 germ. 70-40-70-40(55%) and 40-70(55%). Seed DS for one year at 40 germ. less and more extended.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Cotoneaster p. 126. 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.

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

Add to My Garden

View species page