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Saxifrage
Saxifraga spp.
Reviewed by Kiersten Rankel M.S.
QUICK ANSWER
Offset division is the fastest method and gives a finished plant in 4 to 6 weeks, so most growers start here.
Rosette cuttings work for tight cushion and encrusted types in 6 to 10 weeks but rot if kept too wet. Seed sowing produces the most plants but takes 4 to 6 weeks of cold stratification and a year before seedlings are large enough to handle.
Rosette cuttings work for tight cushion and encrusted types in 6 to 10 weeks but rot if kept too wet. Seed sowing produces the most plants but takes 4 to 6 weeks of cold stratification and a year before seedlings are large enough to handle.
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Offset division
Best for mat-forming and runner types like London Pride
Rosette cuttings
Best for tight cushion and encrusted Saxifrage
From seed
Best for raising a flat of mixed alpines from seed
Offset division
Time
4–6 weeks to establish
Level
Beginner
Success rate
High
You'll need
Established Saxifrage clump with side rosettes
Sterile sharp scissors or knife
3-inch pots or a prepared garden spot
Gritty alpine mix (potting soil with extra grit and perlite)
Coarse grit or fine gravel for top dressing
1
Lift the clump in spring or early autumn
Wait until soon after flowering ends. Slide a hand fork under the clump and lift the whole mat with most of its roots intact. Many Saxifrage spread by short runners, so the rosettes will already be partly separated.
2
Tease offsets apart with thumbs
Sit the clump on the bench and gently pull rosettes apart, working from the outside in. Each piece needs at least a few thread-thin roots and one full rosette of leaves. If two rosettes will not separate, snip the runner with sterile scissors.
3
Trim damaged roots cleanly
Snip off any brown or mushy roots so only firm pale roots remain. Saxifrage offsets recover much better when planted with a clean root system rather than crushed or rotting tissue.
4
Pot up in gritty mix with the crown above soil
Fill a 3-inch pot with mix that drains fast, mixing two parts potting soil with one part grit and one part perlite. Settle the offset so the crown sits just above the soil surface, never buried.
A buried crown will rot within a week.
A buried crown will rot within a week.
5
Top dress with coarse grit
Add a quarter inch of grit or fine gravel around each rosette. Grit keeps the crown dry and discourages slugs and crown rot, both of which target this group of alpines.
6
Water in and grow on cool
Water thoroughly once to settle, then keep just damp for the first 2 weeks. Set pots in bright filtered light or morning sun only. New roots fill the pot in about a month and the plant is ready for the garden by then.
WATCH FOR
A blackened crown with rosette leaves wilting from the center outward. That is crown rot from a buried crown or overhead watering.
Lift the offset, trim back to firm white tissue, and replant with the crown clearly above the grit topdressing. Saxifrage hates wet collars more than almost any other condition.
Lift the offset, trim back to firm white tissue, and replant with the crown clearly above the grit topdressing. Saxifrage hates wet collars more than almost any other condition.
Rosette cuttings
Time
6–10 weeks
Level
Intermediate
Success rate
Moderate
You'll need
Sterile sharp scissors or razor blade
Healthy outer rosettes from the parent cushion
Rooting hormone (recommended for slow-rooting types)
Pure sharp sand or 50/50 sand and perlite
Shallow tray or pots with drainage
Cool bright spot, no direct midday sun
1
Take cuttings in late spring or early summer
Choose outer rosettes that look fresh and full. Slip a sterile blade as far down into the cushion as you can reach and slice off the rosette with a half-inch stem still attached. The stem stub is what will form roots.
2
Strip the lower leaves
Pinch off the bottom 2 to 3 leaves so the stem stub is bare and clean. Be careful not to break the central growing point. This is the most common rosette-cutting mistake and ends propagation immediately.
3
Dust with rooting hormone
Tap the bare stem in IBA rooting powder and shake off the excess. Encrusted and cushion Saxifrage are slow to root and a thin coat of hormone speeds the process from 12 weeks down to about 8.
4
Stick into pure sharp sand
Saxifrage rosettes rot in standard cutting mix. Use pure sharp sand or a 50/50 sand and perlite blend. Open a small hole, slide the stem in to bury the bottom half-inch, and firm the sand against the stub.
5
Hold cool with light shade
Keep the tray at 55 to 70 F in bright shade or under morning sun only. Skip humidity domes for cushion types since trapped moisture causes rot. Mist lightly twice a week instead.
A dome is fine for mat-forming types like S. stolonifera.
A dome is fine for mat-forming types like S. stolonifera.
6
Pot up at 8 weeks
Try a gentle tug. Slight resistance means roots have formed. Pot rooted cuttings into 2-inch pots of gritty alpine mix and grow on in a cool bright spot. Step up to a final pot or garden spot the following spring.
WATCH FOR
Rosettes turning yellow from the bottom up while the crown looks fine. That is stem rot at the buried stub from too much moisture.
Let the sand dry slightly between waterings and pull any rosette that wobbles when nudged. One rotting cutting can spread to neighbors over a week, so checking weekly matters.
Let the sand dry slightly between waterings and pull any rosette that wobbles when nudged. One rotting cutting can spread to neighbors over a week, so checking weekly matters.
From seed
Time
12–14 months to plantable size
Level
Intermediate
Success rate
Moderate
You'll need
Fresh Saxifrage seed (under a year old)
Acidic seed mix or fine peat-perlite blend
Shallow seed pan with drainage
Plastic bag for cold stratification
Spray bottle of softened or rainwater
1
Collect seed when capsules turn brown
Watch the dried flower stalks in midsummer. Snip the whole stem when the capsules start to crack and tip the dust-fine seed into a paper envelope. Saxifrage seed is tiny, so work over a clean white surface.
2
Cold stratify for 4 to 6 weeks
Mix the seeds with a pinch of damp sand or sphagnum, seal in a plastic bag, and place in the fridge at 35 to 40 F. Most Saxifrage species need this cold period to break dormancy.
3
Surface sow on damp acidic mix
Fill a shallow pan with damp seed mix and tap the surface flat. Sprinkle the seed evenly across the top. Do not cover, since Saxifrage needs light to germinate and the seed is too small to bury.
4
Bag the pan and water from below
Slip the whole pan into a clear plastic bag and place at 50 to 65 F under bright indirect light. Water by setting the pan in a tray of water until the surface darkens, then let it drain.
Top watering will wash the seed into clumps.
Top watering will wash the seed into clumps.
5
Watch for tiny green dots
First germination shows up in 3 to 6 weeks as a film of green dots on the surface. Open the bag once a day for fresh air starting at the first germination. Damping-off can wipe out a tray quickly.
6
Prick out at 6 months
Leave seedlings in the pan for half a year until each has a tiny rosette of true leaves. Lift small clumps with a teaspoon and pot into 2-inch pots of gritty alpine mix. Grow on for another 6 months before planting out.
WATCH FOR
Seedlings collapsing in patches across the pan. That is damping-off fungus, the top killer of Saxifrage seedlings under cover.
Pull off the bag immediately, let the surface dry slightly, and water from below only until the seedlings recover. A weak chamomile tea drench can slow further spread.
Pull off the bag immediately, let the surface dry slightly, and water from below only until the seedlings recover. A weak chamomile tea drench can slow further spread.
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About This Article
Kiersten Rankel M.S.
Botanical Data Lead at Greg · Plant Scientist
Editorial Process
Propagation methods verified against Saxifraga spp. growth data from Greg's botanical database, cross-referenced with USDA hardiness zone data and published horticultural research.
USDA hardiness zones 4a–9b