Yes, alpine plants survive winter without much fuss. Alpine plants winter survival is built right into them. These species grew up above the tree line, where winters are far harsher than anything your garden can throw at them. A plant from a wind-scoured ridge at 8,000 feet will shrug off ordinary garden frost with ease.
Think about where these plants come from. On high mountain slopes the cold lasts for months. Snow buries everything and the wind never stops. The frost that kills your tomatoes is a mild day to a saxifrage or a houseleek. Cold itself is rarely what threatens these plants.
The biology behind this is neat. As the air cools, many alpines make antifreeze proteins. These proteins grab tiny ice crystals and stop them growing big enough to tear cell walls apart. The plant also rebuilds its cell membranes. It swaps in more flexible fats so the membranes stay supple instead of going brittle in deep cold.
Two more tricks keep their tissues alive. Some plants use supercooling. This lets the water in their cells stay liquid well below the normal freezing point. Others use freeze tolerance. Ice forms in the gaps between cells but never inside them, so the living tissue stays safe. Both methods carry your plant through the worst of the season.
Here is the part that catches people out. Cold is rarely the problem, but wet is. The same plant that laughs off a hard frost in dry soil will rot at the crown in cold, soggy ground. Standing water around the roots and the base of the rosette does far more harm than any freeze. This matters most when you are overwintering alpines in a normal garden bed.
A dry alpine in deep cold lives. A wet alpine in mild cold dies. Get the drainage right and you solve most winter losses before they happen.
So your winter care comes down to keeping water moving away from the plant. Start with drainage, because heavy clay that holds moisture is the enemy. Mix in plenty of grit or build a raised bed so the rain drains straight through instead of pooling around the roots.
A top-dress of horticultural grit around the neck of each plant makes a real difference. The grit lifts the crown and leaves just clear of the wet soil surface, so the most rot-prone part of the plant stays dry even after a downpour. It is cheap, it looks neat, and it solves a problem that kills more alpines than frost ever will.
Cushion plants need extra care because their tight domes trap moisture against the crown. For solid winter wet protection, prop a pane of glass on bricks a few inches above the cushion, leaving the sides open for air. The glass keeps persistent rain off while cold air still reaches the plant. A sheltered spot in the rain shadow of a wall or a large rock does much the same job for you.
You do not need to wrap your alpines in fleece or haul them indoors. That extra warmth and trapped moisture often does more harm than the cold ever would. Leave them out in the open air and let them do what they were built to do.
Match the species to your conditions and you will lose very few plants. Hardy alpines want a sunny, open, free-draining home where the air moves and the water runs off fast. Give them that, keep the rain off the fussy cushions, and your plants will come through winter looking better than half the things in your borders.
Read the full article: Alpine Plants: A Complete Grower's Guide
