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About the plant What it is and where it grows — not part of any germination protocol.
The plant
Habit Bulb, Ground Cover, Perennial Extension Gardener Plant Toolbox
Habit rhizomatous geophyte Plants of the World Online
Height 1-1.5 ft 30-45 cm Extension Gardener Plant Toolbox
Spread 1-1.5 ft 30-45 cm Extension Gardener Plant Toolbox
Flower Blue, Pink, Purple/Lavender, Variegated, White Extension Gardener Plant Toolbox
Blooms Spring Extension Gardener Plant Toolbox
Native range China North-Central, China South-Central, China Southeast, Hainan, Qinghai, Tibet GBIF Backbone Taxonomy
Hardiness zones 4-9 Extension Gardener Plant Toolbox Growing conditions
Sun Full sun; Partial Shade Extension Gardener Plant Toolbox
Soil High Organic Matter Extension Gardener Plant Toolbox
Soil pH Acid (<6.0) Extension Gardener Plant Toolbox
Moisture Good Drainage Extension Gardener Plant Toolbox 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; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.
Worth knowing Also called roof iris and wall iris. It is hardy in Britain but flowers poorly there, as the summers are not hot enough to bake its roots. Wikipedia: Iris tectorum This source reports 7 treatments. All are shown.
Protocol 1 N. C. Deno, 1993 Difficulty Low Rated by us, not by the source.
Start around February 1, 2027 for a May 3 last frost.
1 Sow and cover
Temperature: 70°F 21°C · Light: light
No stated waiting before sowing. Then 63 days to germinate.
100% germination in 28–63 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 N. C. Deno, 1993 Difficulty Moderate Rated by us, not by the source.
Start around December 1, 2026 for a May 3 last frost.
1 Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
2 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C · Light: light
about 3 months from start to step 2. Germination happens during step 2, in 35 days.
100% germination in 35 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 N. C. Deno, 1993 Difficulty Moderate Rated by us, not by the source.
Start around September 3, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 2, 2026.
1 Dry storage
Duration: 180 days · Temperature: 70°F 21°C
2 Sow and cover
Temperature: 70°F 21°C · Light: light
about 6 months from start to sowing. Then 35 days to germinate.
50% germination in 35 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 N. 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 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
24 germinated in this phase.
2 Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
3 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
about 6 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.
36% germination.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 N. 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 days · Temperature: 40°F 4°C
2 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
8 germinated in this phase.
3 Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
4 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
about 9 months from start to step 4. Germination happens during step 4; time not stated, 21 days assumed.
20% germination.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 N. C. Deno, 1993 Difficulty High Rated by us, not by the source.
Start around August 27, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on August 26, 2026.
1 Dry storage
Duration: 180 days · Temperature: 70°F 21°C
2 Sow and cover
Temperature: 70°F 21°C · Light: dark
about 6 months from start to sowing. Then 42 days to germinate.
14% germination in 42 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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 7 N. C. Deno, 1993 1 Sow and cover
Temperature: 70°F 21°C · Light: dark
No stated waiting before sowing.
0% germination.
Nothing germinated at 70.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Iris p. 156Public domain Show the original text Iris (Iridaceae). This genus gave -not only great diversity in germination behavior but also some of the most extended multicycle germination observed. Germination is always hypogeal, and true leaves develop in 'a week or two once the radicle emerges even when germination was delayed for years. Empty seed coats and deformed seeds are relatively easy to recognize so that seed counts and percent germination are accurate. A major problem is how to stimulate the germination of Oncocyclus and Regelia Iris since they have such extended natural germinations. Panayoti Kelaidis of the Denver Botanical Garden has iritorrmed me that Fritz Kummert In Austria, Frank Norris in Tennessee (USA), and David Shahak in Israel are growing Oncocyclus Iris from seed in large numbers. Panayoti said that there are reports that germination was much improved by rinsing the seed in dilute Chlorox (aqueous NaOCI) and rubbing off the seed coats after which the seeds germ. readily at 40. There are also reports that gibberelic acid and other chemicals stimulate germination. Data is needed using scientific procedures. A recent book, "The Iris" by B. Mathew, is devoted to this genus. Mathew divides the genus into six subgenera with further division into sections and series. His arrangement is used only in part. The species are arranged in alphabetical order for convenience with subgenus or section indicated in parentheses using the abbreviations B (bearded), Bx (beardless), E (Evansia), 'N (Nepalensis), .0 (Oncocyclus), P (Pardanthopsis), A (Regelia), At (Aeticulata), and X (Xiphium). I. tectorum (E) germ. better in light as shown by 70L(50% in 5th w) and 70D(14% in 6th w) using seed DS 6 m at 70. There was no further germination over one year. Germination was much lower with fresh seed or with DS seed sown at 40. I. tectorum alba (E) germ. 70L(100% in 4-9 w), 40-70L(100% in 5th w), and none in 70D or 40-70D using fresh seed. If the sample in 70D is shifted to 70L after 2 m, germination is 100% in 5th w showing that 2 m in 70D had no effect Germination is much extended in the dark, and some samples germ. significant amounts in dark treatments. An example is 70(24%)-40-70(36%) .40-70(8%)-40-70(20%). There was some deterioration in seed DS for 6 m at 70. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Iris p. 156. 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.
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