Plant of the week – Curl-leaf Mountain Mahogany

multiple grey barked stems with small, elliptical green leaves

grey bark of young branches

I just love Curl-Leaf Mountain Mahogany (Cercocarpus ledifolius) and it is way under-utilized in landscaping!

This xeric shrub – actually more like an architecturally diverse tree when it is happy – survives drought with aplomb and thrives in rocky, poor soils as well as loamy soils.  It is just fine with extreme temperature ranges so it is great if you have a hot, dry spot but it doesn’t mind wind and cold.  Mature plants may reach 30′ in height and are very long lived.  Supposedly one was known to be 1350 years old and succumbed only to a saw.

green narrow leaves surround cluster of small yellowish flowers


Often found on rocky slopes throughout the Western US, it is browsed by a variety of mammals (including cottontails and deer.)  When browsed it becomes bushy and thick but it’s natural habit is upright and slender when young, creating a large multi-branched canopy when mature.

Curl-leaf Mountain Mahogany’s beautiful light grey bark is a terrific background for it’s dark green leaves, which though narrow, elliptical, curved (hence the common name) and rather leathery, are evergreen!  Clusters of yellow-orange trumpet-like flowers cover the branches in early summer.

many branched large shrub

Curl-leaf Mountain Mahogany shrub

Slender, tapered achenes (seeds) approximately 1/2″ in length have two inch long, curled, wispy awns that make the shrub look like it has curly hair.  Seed production is quite variable depending on the climactic conditions of various years.

This beautiful member of Rose (Rosaceae) family is useful as a focal point of a large garden space or in a landscape setting that calls for a plant with visual movement and interest.  It’s hardy, needs little care and provides green color all year long.

flowering branches of Curl-leaf Mountain Mahogany

flowering branches of Curl-leaf Mountain Mahogany


Planting seeds

ARNSORseeds.webFall is the best time to put established plants (ie in pots) into the ground.  Hands down, no contest.

Plants will need to be watered for a few weeks to help roots make connections with the soil around them and in fall we typically get rains that help moisten the soil sufficiently to allow roots to establish in the soil before winter freezing which prepares plants for rapid growth in the spring.

Fall is also the best time for planting seed of many species of native plants.  This mimics what happens in the wild where seeds naturally fall from plants onto the ground during the heat of summer.  If not eaten by insects, birds or small mammals and if they land a site that can maintain moisture, they will germinate.  Some seeds germinate in early fall and remain green underneath the protective blanket of snow.  Others need to undergo periods of cold, moist stratification and respond to changes in light and temperature before they will sprout in the spring.

Some native species prefer spring sowing, especially asters, grasses and some dry land species.  These species typically require warm temperatures as well as moisture for germination.  Many of these species are found on the open plains.

cluster of Arrowleaf Balsamroot (Balsamhoriza sagitatta) seeds and ruler

Arrowleaf Balsamroot (Balsamhoriza sagitatta) seeds

Montana species best for springtime planting:

a cluster of Blanket Flower seeds

Blanket Flower (Gaillardia aristata) seeds


Montana species best seeded in the fall:

Whether planting in spring or fall, seeds may be sown either directly onto a site or into containers for planting out after seeds have germinated.
Each method has its advantages:

CAMROTseeds.webDirect sowing:

  • only have to plant once
  • less materials (no seed starter or pots to use)
  • cheaper (in terms of resources and time)

Sowing in containers:

  • easier to monitor and control moisture levels as seeds germinate
  • greater success rates
  • less predation (by birds and animals)

Whichever method you use, the critical time for all seeds is when they begin to germinate. Seeds must be kept moist until they establish their roots into the soil, usually this takes about 2-3 weeks.  If they dry out even once they will die.

If you are looking for seeds of native species:

  • collect your own and store them in paper envelopes
  • buy from reputable companies like Native Ideals Seed Farm in Arlee, MT that specialize in native species
  • share seeds with friends that you know gather seeds in an ethical manner

A Plant in a Pot is Not the Same as a Plant in the Ground!

Plants in pots are not as winter hardy as plants in the ground – we all know that – and most of us have lost our share of plants we had hoped would make it through the winter in a pot.

large thimbleberry in tan pot

Thimbleberry in a pot

Often the issue is not winter freezing, but the thaw-freeze cycle of spring.  Native plants expect to freeze, but they also expect to have their roots nestled in soil that maintains warmer and more consistent temperatures than above ground.  Plants in pots are exposed to the dramatic changes in temperature often suffering root damage as they warm in springtime sunshine followed by freezing at night.

so… how to get potted plants to survive:

Avoid dark-colored pots that heat up quickly in the sun.  Unfortunately for those of us in the nursery business who use black plastic pots (used to keep roots dark during the growing season), avoiding using dark pots is not realistic.

A second option is to nestle pots in an insulating material that prevents sunlight from hitting the pot and keeps temperatures more consistent.  This may be accomplished with compost, straw, pine needles or whatever mulch material you use.

Third, consider moving pots to a shaded spot where sunshine won’t hit the pot in spring.  This helps moderate temperature fluctuations.

Stonecrop seedlings in pots

Stonecrop in pots

Other tips:

  • Make sure pots have adequate drainage to minimize how much time the plants roots are sitting in water as the pot thaws in the spring.  Roots drown if sitting in water for more than a week or so.
  • Avoid overwintering in unglazed clay pots that crack as water in them freezes and thaws.

Most native species winter nicely in protected pots.  We’re experimenting with planters and have been pleased with the overwintering results.  Tell us about your experience with overwintering in pots!


Special thanks to UM PLAN students who spent the afternoon helping us move thousands of plants from their winter storage in the hoop-house to their summer home in the nursery.  A huge heartfelt thank you to all 5 of them!!

5 UM FLAT students sitting on wagons and carts

UM FLAT students

Overwintering plants in pots is a challenge!  Roots of plants in pots are far more vulnerable to weather extremes than roots of plants in the ground.  Especially damaging are the freeze-thaw cycles of our Montana springtime.

Our goal for winter storage is to ensure that plants go dormant before they freeze, then to keep them frozen until it is sufficiently warm in the daytime that they can begin growing with minimal freezing at night – i.e. we have to read Mother Nature’s mind to find out when she’s finished with winter temps.  Right!

While many nurseries avoid this situation by either selling off stock in the fall or using greenhouses to alleviate temperature fluctuations, we believe our plants are hardier when not grown in greenhouses and we have virtually no carbon footprint by not heating a greenhouse or running fans and lights.

That said, the challenges of overwintering are numerous between freezing, dessication, rodents and breakage from stacking plants in storage.  It’s a delight to be up and growing again!  Thanks again to our friends from the UM FLAT program!

Digging from the Wild?

new leaves of columbine emerge between old plant stalks


Digging native plants from the wild?  Unfortunately most of us have tried it at some point.  And most of us have failed.  Lots of native plants just don’t like to be dug up and moved.

But there are bigger issues at stake than just trying to transplant.  Like, what happens to that hole you leave in the soil?  All depends on which weed seed arrives there first.  Disturbing the soil opens it to weed seeds that either fly in, are deposited on the site by animals, or have been sitting on the site dormant, just waiting for the soil to be broken open for them to start sprouting.

And what happens to species (e.g. Echinacea angustifolia) that get dug up by too many people and suddenly find themselves few and far between?  Depletion of populations of native plants is happening all around us as development eradicates plant communities.  Digging plants from the wild doesn’t help the situation.

single plant of Arrowleaf Balsamroot with many yellow ray flowers

Arrowleaf Balsamroot

I know, digging just this one little plant won’t have any noticeable effect.   Something akin to removing cool rocks from National Parks or fossils from old deposits…. OK, I’m experiencing guilt for digging up that plant years ago.  But I know better now and won’t do it again!

Really, it DOES make a difference.  Please don’t dig plants from the wild.  See if you can find a nursery that sells the species you are looking for, or gather seeds and propagate them.  Or give me the seeds and I’ll grow them for you!


It’s time to prune!

dense blue-green foliage of Rubber Rabbitbrush needs pruning!

Rubber Rabbitbrush needs pruning!

This week we’re pruning the shrubs in our demonstration gardens as the snow melts off but before leaves emerge (yes, we still have snow!).


orange branches of wax currant with small leaves beginning to emerge

Wax Currant beginning to bud

Pruning maintains the health and vigor of plants by removing dead, diseased or injured material and allows  control of the shape of the plant while promoting fruit and flower yield by concentrating the plant’s energy.

This Rubber Rabbitbrush (Ericameria nauseosus) needs a heavy annual pruning to keep it bushy and under control.   It seems like the more I chop it back, the more vigorous it gets!  Other species like this Wax Currant (Ribes cereum) and our Blue Rock Clematis (Clematis occidentalis) need more careful pruning.

purplish buds of Blue Rock Clematis on branches of vine

Leaf buds on Blue Rock Clematis

We use very sharp, clean pruning shears on smaller plants and pruning saws on large trees.   Our pruners have been sharpened and bleached in a 10% bleach solution.  It’s important to maintain sanitation and avoid transporting bacteria or viruses on shears.

We prune using the concept of ‘apical dominance’ which means that the plant has a propensity to have one main leader with all the other branches lower than the ‘main’ branch.  Cuts are made just above buds that are pointed in the direction we want the branch to take.  Our goal is to keep plants appropriately shaped (each species has its own form) and to help keep shrubs in the demonstration beds compact.

When to prune:

  • Trees and shrubs – ideally after buds swell and before leaves emerge so sap will seal cuts (fall pruning may open the
    new leaves of columbine emerge between old plant stalks

    emerging leaves of Columbine

    plant to disease since no sap is running to seal cuts) but light pruning may be done any time of year

  • Grasses may be pruned either after flowering to prevent reseeding or in the fall if you don’t want them for winter interest in your garden.  If you wait until spring (like we have done), prune back as far as you can without damaging new growth.
  • Wildflowers may be deadheaded after flowering to promote second blooms or to minimize reseeding, but leave at least half of the plant mass so the plant can accumulate sugar reserves it needs to make it through the winter.  Some flowers like this Blue Columbine (Aquilegia coerulea) need to have old growth removed to make way for regrowth in the spring.
dense cluster of dozens of orange stems of Mockorange shrub

This Mockorange needs to be thinned!

This Mockorange (Philadelpus lewisii) shrub  needs to be thinned out to promote fewer healthy branches rather than lots of spindly suckers.

And of course, pruning provides cuttings for vegetative propagation which is a subject for another blog another day.

pruning shears cutting a branch of Blue Elderberry just below leaf bud

Pruning Blue Elderberry