By Yvette Henson, San Miguel Basin Extension
By the end of January, we had close to average snowpack statewide. This was encouraging after last years (and previous years) droughts! In February and into this first week in March, we have had quite a bit of snow in my region of the state which I am sure has resulted in above average snowpack for February. The Colorado Snow Survey & Water Supply News Release for February hasn’t been published at the time I am writing this blog, but when it is released, you can find it here: https://www.nrcs.usda.gov/wps/portal/nrcs/main/co/snow/waterproducts/supply/
Update March 9th-- imagine my surprise to learn when the report come out yesterday afternoon, that even though we received more than 4' of new snow the last week in February at my 8,400' elevation in SW CO, we are still only 95% of average snow pack for 2022.
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| snow covered landscape |
Snow can be like an insulating blanket over plants to protect them from frigid temperatures and desiccating wind. Temperatures at ground level under snow can be degrees higher (even above freezing) and fluctuate less than air temperatures.
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| soil temperature is lower under snow cover, protecting the developing crowns on these native goldenrod Solidago sp. |
Light can penetrate the snow cover. It is interesting that light can only penetrates to a depth of 12-20” through snow in the fall but to a depth of more than 6’ in the late winter and spring! The angle of the sun, the daylength, as well as properties of the snow affect the timing, the amount and the quality of the light that reaches plants under the snow. In the late winter, the light penetration through the snow triggers some seeds to germinate and some species to develop buds in their crowns in preparation for spring regrowth. A classic example of a Colorado native plant that develops leaves and floral structures under snow are avalanche lilies. As the snow melts in the spring, the flowers bloom.
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| yellow avalanche lilies (Erythronium grandiflorum) and spring beauties (Claytonia lanceolata) |
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| red foliage on emerging plants, right after snow-melt |
We gardeners learn which plants do well under snow cover and which don’t. We often learn this the hard way. Not all plants do well with snow cover. In this case, it is often the wet soil under the snow rather than just the cold that kills these plants during winter. A general rule is to research the environmental conditions of where a plant is native to. If it is an area with no snow fall and you typically have snow cover in the winter, you could site those plants on south facing slopes and/or against structures with south and west exposures where snow melts more quickly. In a similar way, snow will melt quicker off rock mulch than bark or leaf mulch. Plants that come from areas that do receive snow can withstand colder temperatures with snow cover than without and don’t mind ‘wet feet’.
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| south facing berm and gravel mulch absorb heat and melt snow quicker-- this is a good place for plants that don't overwinter well with snow cover |
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| North facing (same berm) as previous photo has more consistent snow cover-- this is a good place for plants that do well with snow cover. |
Snow load can break branches of woody shrubs and trees, especially where it lands after falling off roofs. If you have this situation in winter, you can plant shrubs that respond well to being cut back to ground level in the spring. Some examples are elderberries (Sambucus spp.), grown for their foliage, dogwoods (Cornus spp.), grown for their colorful winter branches and butterfly bushes (Buddleja spp.) It can be done with many multi-stemmed, summer flowering shrubs that form their flower buds on the current season’s growth. This severe pruning stimulates multiple stems to regrow from the base and may keep your shrubs smaller in stature, depending on their growth rate.
Fascinating insights that I had never taken into consideration. Very helpful recommendations on plant locations for those on the edge of the zone ranges.
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