A close up of frost heaves
A common winter sight in most cold temperate regions are frost-heaves; areas of water-saturated soil that have been uplifted due to freezing.
Frost-heaving is generally regarded as an undesirable dynamic, because it evidences a lack of organic material or mulch capable of sheltering the soil (and it’s microinhabitants) from freezing.
However, on degraded and compacted sites, frost heaves are really a great opportunity for establishing vegetation which can ultimately protect and nurture soil life.
Also, in the coldest of winters, frost heaving can occur everywhere throughout a forest, regardless of how much humus is present.
Since these deep-freeze events are infrequent, they likely ultimately benefit forest. Particularly in areas with heavy clay soils that can easily become anaerobic and compacted through the natural process of soil settling.
Frost-heaves aerate the topsoil and can mix the A and B layers of the soil, re-invigorating soil organisms by giving them the raw subsoil material to work with.
Seeding into frost heaves is a simple affair, however timing can be a critical component of success since frost heaves tend to be isolated events cause by prolonged cold snaps.
Heaves are not always consistently present, and can tend to form at night and melt away during the warmth of a sunny day.
Frost heaves also come in different depths. While it would be hugely tedious to get a measure on each heave, you can roughly tell how deep they are by the extent to which they have heaved upward.
The more they have heaved upward, the more likely they descend deep into the soil.
Young forbs seeded into shallow frost heaves
Honey locust tree seeded into deep frost
heaves in late-winter, after having been
Depending on the planting depth of your seeds, it may be prudent to reserve larger, deeper-planted seeds for your deeper frost heaves cycles.
Conversely, waiting for shallower frost heaving cycles for smaller shallow planted seeds can make a significant difference in establishment.
For those who have broadcast seeded, seeding into frost heaves is no different. Find areas where the soil is opened up, and cast your seeds.
As the soil thaws and soil temps rise to satisfactory levels, the frost heaves will collapse, covering the seeds and providing the needed moist soil contact to initiate germination.
A Case Study:
I have successfully germinated plants from seeds sown into frost heaves on many occasions and in many conditions. An area of the Windward Education and Research Center property (called North Umbria garden) was historically used as a logging skid. All top soil and vegetation was scraped from the site, and systemic compaction has rendered it a barren moonscape.
Over the last three years, this 2-acre site has been under intensive restoration and seeding into frost was one of the first and primary mechanisms to establish the initial pioneer legumes.
I have also expanded the practice of seeding into frost heaves and begun sowing inoculated alfalfa and white-clover, as well as deep rooted forbs such as common mullein (Verbascum thapsus) curly dock (Rumex crispus), forage turnips (Brassica rapa), dandelion (Taraxacum officinale), and chicory (Cichorium intybus) seed into frost heaves over an approximate 20 acre swath of rocky, almost-barren oak Savannah in preparation for this system to be utilized as a grazing/forage paddock system.
Second spring season of mostly alfalfa
I have found that most plants are somewhat tolerant of this method of seeding. However, every plant wants slightly different conditions to germinate, and so many are less successful than others.
Heavy seeds such as alfalfa, clover and turnips seem to respond well to this method, as their seeds bounce and fall into the holes nicely.
Light, fluffy seeds such as dandelion, curly dock, and chicory tend to be difficult to get inside the the heaves — instead they stick to the ground or float away. Thus success with these species has been not been quite as good.
Mullein, with its tiny seeds, needs to be shallow seeded and most frost heaves tend to be too deep for it to germinate well.
I have not tried any grasses yet, but I presume most would act similar to the heavy seeded plants.
The efficiency of this method is astounding, and is a excellent example of how doing a relatively small amount of work in the right window of time can result in rapid improvement.
I hope that others can share their experience with this method, and be encouraged to try it out in different cold-climates and determine its effectiveness in a wider set of conditions.