Saxifraga 2018

[David Sellars]

Temperatures in this part of the world have been above freezing for all of January and although there has been endless rain and very little sun the Saxes are starting to flower.  Saxifraga Franz Liszt is growing in a vertical tufa crevice under a rock overhang.  This keeps the flowers dry.
Saxifraga Frederik Chopin and Saxifraga Radvan Horny are growing in a plunge bed in the Alpine Shed.

[Jan Tholhuijsen]

Nice pictures David, I start with just a few flower buds in the open greenhouse.

[kris]

very nice plants, Jan and David. I can't grow them like you. Either weather or my mistake  they don't look as healthy as yours.

[David Sellars]

Kabschia Saxifrages should do well in Saskatoon, Kris. They are very cold hardy but cannot tolerate heat.  Kabschias must be kept cool and moist in the summer and I have found that the best location for potted Saxifrages is on the north side of the house in complete shade most of the day but open to the sky.  Shade cloth can be unsatisfactory because it traps the heat.

The best potting mix for Saxifrages has been debated over the years.  Many in the UK use a mix with John Innes compost which is not available in Canada. A few years ago I visited Phil Pearson who ran a Saxifrage nursery near Seattle with Steve Doonan.  The mix they originally developed had very little peat in the mix and Phil has since moved on to just using pumice.

A potting mix only with pumice is too loose for my taste as it all falls apart when a plant is repotted, plus you need a lot of pumice! I now use a mix that is about 50% coarse sand (that also contains rock dust), 25% pumice and 25% limestone chips.  This mix is very free-draining but still clumps together when moist.  Saxifrages love this mix and quickly grow long, healthy, well-aerated roots to the bottom of the pot. The absence of any organic matter does not seem to be a problem and in fact I believe is an advantage as it is impossible to over-water. I suspect that Saxifrage pots with soil or peat in the mix can easily get too warm in the summer. The gritty mix with no peat can be kept well-watered to keep the roots cool.

The rock dust provides mineral nutrients and very little additional fertilizing is necessary.  For the potted Saxifrages I follow the fertilizing practice of Wisley Gardens with dilute high potash fertilizer just twice a year, in the fall and after flowering. It is quite possible that the pumice and limestone chips could be replaced with granite grit. But now that I am happy with my mix I have no incentive to try something different!

The following photos show how well this potting mix works. I made a cutting of Saxifraga Květy Coventry in September 2016 and potted it on in February 2017.  At that time the cutting had formed only tiny roots.  A year later (February 2018) growth has been vigorous and the roots are emerging from the bottom of a 90 mm deep pot.  The white roots are recent root growth.

[Leucogenes]

Thank you very much for the fantastic explanations... David. I have a few saxifraga, but all outdoor in combination with various sempervivum. I'll get some more copies, though. Your comments on the substrate are therefore very helpful.

Thomas

[Jan Tholhuijsen]

Good explanation David. Agree with you about the soil mixes.
With me is a part of the tuf rocks on the north side. 90% of the saxes are doing fine. Photo 1.
Another tuf rock is with me until 4 o'clock in the full sun. In case of hot weather, cool off every day with water bristles. Above 30 degrees, I put umbrellas. photo 2.
No saxifraga loss in the last 3 years. Fingers crossed.
How I made this tuf rock see here.  https://tinyurl.com/the-tuf-rock

[David Sellars]

Great to see your garden beds Jan.  Your Saxifrages are doing very well. You are right that planting on the north side of rocks is key keeping the plants out of full sun at mid-day. I love your umbrellas in the summer! Adrian Young at Waterperry Gardens uses a slatted roof for shade but that has to be a permanent installation.

Here is another year and a half old cutting doing well in a 90 mm deep pot.  Saxifraga Torrisholme Rose.

[kris]

David thank you for the detailed answer to my post. I got about 10 of them mostly kabschias and I usually grow them in the garden. But for the cuttings I will follow your advice. Most of my plants are planted in tufa rocks or in a vertical wall. They are OK but not very floriferous.
I have two pictures of my plants taken last year attached here.
1.Saxifrage sp ( I lost the  name)
2.Saxifraga oppositifolia
both of them grow in tufa.

[kris]

David can you please tell me where you buy the limestone chips  and when is the best time to grow cuttings. This year I want to increase my plants from cutting. My concern is if the saxifrage roots do I have enough time to put in the ground?

[David Sellars]

The local feed stores are remarkably useful sources for different types of grit.  I think it is something to do with turkeys.  You may have a Buckerfields in Saskatoon or equivalent feed store. Below is a photo of the limestone grit bag with a sprinkling of the limestone grit on top. I use #2 granite grit for mulch in the pots.  They used to manufacture it in BC (we have lots of granite) but the feed stores here now carry a product imported from Minnesota! If Donald Trump is reading this score 1 for NAFTA.

The best time for cuttings is September/October as long as they are not allowed to freeze over winter. I use a 50:50 mix of sand and vermiculite and no bottom heat. They root well over winter and can be potted up in February.  The second best time for cuttings is early spring, right now in this part of the world. They root in 8-12 weeks but are still too small to plant out unless you want to plant directly into tufa. I pot them up in small pots and keep them until the following spring for planting out.

[David Sellars]

Kris, your Saxifraga oppositifolia is a good size and has nice flowers. Sorry to hear that some of your Saxes are not very floriferous.  One issue is that some Kabschia Saxifrages are not very floriferous anyway, particularly in the garden. I have been very disappointed with Allendale Angel which sounds nice but has very few flowers.  In our garden some of the most floriferous are Allendale Charm, Winifred, Franz Liszt, Marianna and the early flowering Winton.

Winton is already out in the garden and contrasts nicely with Saxifraga Kathleen. Another good early plant is Saxifraga Jan Neruda seen below growing in tufa.

[kris]

Thanks David.
Your saxifrage jan neruda is very beautiful.
I think I will try my cuttings in September and try to grow them in the basement of the house . In Saskatoon it is impossible to grow them outside in winter. When I tried my cuttings I used pure sand and with rooting harmone. The cuttings rooted but not very robust.
I will try your method this time.

[David Sellars]

Lots of flowering happening here. Saxifraga Moulin Rouge in the plunge bed. Saxifraga Joy Bishop, Bohunka and Allendale Charm in larger pots.

[kris]

David really nice saxifrage with beautiful flowers. Why are you growing them in pots. Is it because you have a green house or may be you start them indoor and plant outside later.
Saskatoon is not easy for many plants. The harsh weather and fluctuating temperature in the spring kill lot of plants. Every year in spring I grieve to see many special plants perished in winter. But soon to see new shoots appear makes me forget all the distress.
Kris

[David Sellars]

Kris, I grow Saxifrages in pots as well as in the open garden.  They flower so early that it is nice to be able to enjoy them under cover. Plus the flowers last longer as they are protected from rain. We have a Garden Room off the house that we use to display plants in flower.




Winter has come back and we had snow today.  Saxes in the tufa cliff are looking a bit bedraggled.



The plunge bed Saxes are still very happy.