Most plants are resilient and can take up to half an inch of ice or a total covering of snow. Improperly trying to remove an accumulation can cause more damage than the ice or snow itself.
The plants most susceptible to damage are those with multiple stems, weak or damaged crotches or branches, and older specimens. One way to prevent damage to these plants is to tie the branches together until the snow and ice melt. You can also tie weaker branches to stronger ones. On plants with multiple leaders, such as arborvitae, you can tie the leaders together with strips of strong cloth or nylon stocking. Just remember to remove any of these ties when the snow and ice season is past. You don’t want these ties to cause damage during the growing season. If for any reason you do need to remove excessive snow or ice, do it gently and when temperatures are near the freezing mark, not when it is subzero. Ice an inch or more thick can be removed with running cold water. Do not use hot water as it will burn the tender plant tissues. Be very careful so the water does not refreeze, causing more damage.
Do not whack the snow or the plants with any tools. You can use a broom to remove snow gently, being careful not to bend the branches more than they already are. You also do not need to remove all the snow, just enough to relieve any excessive pressure on the plant.
If any branches do get broken, remove them as soon as possible. Prune properly to assure healing and new growth in the spring. A broken branch should be cut back to its origin, not just beyond the break, unless the break occurs right at the crotch. In any event, make a clean cut and remove any damaged or frayed bark or wood. Use a sharp knife to remove loose bark back to its attachment point. The latest research has shown that it is better to leave a wound clean than to apply any type of paint to it. Furthermore, keep in mind that trees don’t heal, they just grow over a damaged area. That is why it is so important to clean the damage thoroughly.
In most cases, the best cure for ice and snow on plants is warmer weather.