Deno’s GardenMy Garden

Petrophytum caespitosum

Mat Rock Spiraea · Mat Rockspirea · Rock-spiraea

Family RosaceaeGenus Petrophytum

A dense green mat clinging to a slab of pale limestone, studded with short creamy bottlebrush spikes on red stalks.
The whole plantStan ShebsCC BY-SA 3.0

About the plant

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

Habit
shrubPlants of the World Online
Habit
Perennial, SubshrubPLANTS Database
Flower
WhiteWikipedia
Native range
Arizona, California, Colorado, Idaho, Mexico Northeast, Montana and elsewhereGBIF Backbone Taxonomy

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

Sources: Plants of the World Online — Royal Botanic Gardens, Kew; PLANTS Database — USDA NRCS; Wikipedia — Wikipedia contributors; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

This source reports two treatments. Both are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Moderate Rated by us, not by the source.

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

  1. Sow and cover

    Temperature: 70°F 21°C

No stated waiting before sowing. Then 14 days to germinate.

46% germination in 14 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Petrophytum p. 190Public domain
Show the original text
Petrophytum (Rosaceae). P. caespitosum germ. 70(46% in 2nd w) and 40(6%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Petrophytum p. 190. 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 Very high Rated by us, not by the source.

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

  1. Cold moist stratification

    Temperature: 40°F 4°C

Germination happens during step 1; time not stated, 21 days assumed.

6% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Petrophytum p. 190Public domain
Show the original text
Petrophytum (Rosaceae). P. caespitosum germ. 70(46% in 2nd w) and 40(6%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Petrophytum p. 190. 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