Cold comfort gardening

Will our gardens recover from last month's record low temperatures, and what can be done to protect them from snow and icy conditions, writes JANE POWERS

AT THE TIME of writing, it is eight degrees Celsius outside my window, and the night-time temperature has not sunk below freezing for at least half a week. This is balmy weather, compared to the stuff that blasted through our gardens over the past couple of months. On the coldest night, the thermometer here dipped to minus 5 degrees, the lowest value I’ve ever logged in our garden.

But we live in the mildest part of Dublin, just half a kilometre from the coast as the seagull flies; elsewhere in the county it was 10 degrees colder. And in Straide, Co Mayo, the temperature tumbled to minus 17.5 degrees. Last month was Ireland’s coldest December on record.

What does this mean for our gardens? Are those plants that emerged from the snow and ice as sodden rags and bare sticks irrevocably damaged? Will they live to leaf up again? Or should we cut our losses now, and hurl their sad remains onto the compost heap?

No! Not so fast. Belay there with that spade. Herbaceous perennials and deciduous woody plants will recover as these come from habitats with colder winters than ours. In fact, some perennials, such as delphiniums and peonies, will be better than usual next summer. This hard weather reminds them of their homelands.

Most other plants – evergreens, that is – cannot reliably be declared dead until springtime. Although they have been stunned by the extreme cold, many will revive, producing new growth from near the base, or even from below ground.

The best approach is to leave the dead-looking bits on the plant to protect it for the rest of the winter. In late spring, if no new shoots are apparent, don’t give up until you have done a final investigation. With a sharp implement – secateurs, knife or fingernail – scrape away the surface layer of the stem. If you find fresh green material underneath, your plant will live to tell the tale of its coldest ever winter.

Who knows what the rest of the winter will bring, but it’s best to be prepared for further meteorological assaults.

FROST

If cold weather is predicted, protect vulnerable evergreen plants with horticultural fleece, or with burlap or polypropylene sacking. Even newspaper is better than nothing. Try to create an insulating tent around each specimen. Prolonged frost can cause the soil to buckle, which can destabilise roots, and allow them to dry out. As soon as it thaws, press the soil back into place, along with any plants that may have lifted.

WIND

Cold winds can be especially damaging to evergreen conifers, causing them to lose moisture, and their foliage to become scorched. If the plants are small, you can wrap them up, or erect a windbreak. In spring, cut off the damaged parts. When planting vulnerable specimens in future, choose a more sheltered spot.

“Wind rock” may be a problem with all woody specimens, particularly newly planted ones. This is where the breeze catches a plant and tosses it back and forth, or even around in circles, so that the stem wears a groove in the soil.

Such plants should be stabilised, and the hole filled in. If the specimen is top heavy, consider removing some of the weight.

SNOW

Snow is a great insulator, and is less damaging to the garden than severe frost or cold winds. It will do no harm to perennials, or to deciduous trees. However, its weight can break the branches of evergreens, and cause hedges to splay apart. Use a yard brush to knock it off, before it becomes too heavy.

If you have a taller evergreen that you can’t reach, try throwing snowballs at the branches (a neighbour did this for me, after one of our trees dropped a limb in the snow). If you have a polytunnel, brush the snow off, as its weight can rip the plastic, and even collapse the entire structure.

CREATURE CARE

Noxious gases from decaying matter can build up in frozen ponds, and can be fatal for frogs or fish.

Don’t be tempted to bash a hole in the ice, as the shock waves can be harmful to pondlife. Instead, place a pot of very hot water on the ice so that it melts a hole.

If there is snow, clear a patch off, so that birds don’t have too far to reach down to the water for a drink, and for water for preening. If you don’t have a pond, be sure to provide a bird bath. Many birds will not survive in cold weather without our intervention, so keep the feeders and bird table topped up. Ground-feeding birds are especially vulnerable in snowy weather, so scatter some food where they can reach it.

FINALLY, SOME GARDENING

Look out for emerging snowdrops and crocuses, and clear the weeds and unsightly plant debris from around them. Likewise, you can snip away the raggedy bits of herbaceous perennials. But leave their seedheads for structure, and to provide food for birds and sheltering places for insects. Spread garden compost or seaweed onto vegetable beds, and onto asparagus beds.