One of the most unsettling things you can find in an Irish garden in March is a shrub that looked perfectly healthy two days ago now showing blackened, collapsed new growth after a cold night. It looks serious. It looks like the plant has been badly damaged or even killed. In the majority of cases it is neither of those things, and understanding why will save you from making a hasty decision, cutting back hard or writing the plant off, that the plant itself does not require.

What you are looking at when you see that blackening is the consequence of a pattern that has become increasingly common in Irish gardens as our climate shifts. We get a mild spell in February or early March, sometimes an extended one, warm enough to feel genuinely spring-like, and the plants respond to it exactly as they are designed to. Shrubs that would once have stayed dormant until April begin to push new growth in late February. Herbaceous plants that would have stayed below ground send up fresh shoots. That new growth is tender in a way that established growth is not. It has no hardening, no waxy cuticle built up over time, no resistance to cold. When a frost follows, as it regularly does in an Irish March, sometimes sharply, that tender growth takes the hit.

The key distinction to make is between damage to the new growth and damage to the plant. These are not the same thing. A shrub that has had its new March shoots blackened by frost has lost that flush of growth. It will not recover those particular shoots. But the buds that were further back on the stems, the ones that had not yet broken into growth, are almost certainly intact. Within a week or two of the cold passing, you will see new growth appearing from those buds, and the plant will continue its season largely as normal. It will not be set back significantly. The display might be slightly delayed or reduced, but the plant is not in trouble.

There are situations where frost damage is more serious, and it is worth knowing what they are. Plants that are genuinely frost tender, things that should not be outside at all in an Irish winter, or that need the protection of a sheltered south-facing wall, can suffer lasting damage if caught by a hard frost in early growth. Echiums, tree ferns, and some of the more tender pittosporums fall into this category. If the growing tip of such a plant is killed, it may not regenerate from further back in the way that a hardy shrub will. For these plants, protection matters and timing of exposure to outdoor conditions matters. But for the vast majority of garden shrubs, the buddleias, hydrangeas, hebes, escallonias and hardy herbaceous plants that make up most Irish gardens, a late frost causing blackened new growth is a temporary setback, not a lasting problem.

The advice on what to do after a frost has damaged new growth is straightforward: wait. Do not rush to cut off the blackened material immediately. Leave it for a week or two until you can clearly see where the new growth is coming from further back on the plant. Cutting too early can leave you removing more than you need to, and it exposes fresh cuts to any further cold that might follow. Once the weather has settled and the new growth is clearly underway, you can tidy up the damaged material if it bothers you aesthetically. In many cases you will find that the new growth quickly overtakes the blackened tips and the damage becomes invisible within a few weeks.

The broader lesson here is one that Irish gardeners are having to learn and relearn as our seasons become less predictable. A warm February is not a safe February. The last frost date in most parts of Ireland is somewhere between late March and mid-April, and in exposed or inland gardens it can be later still. Plants that respond to early warmth are following their programming. They cannot read a forecast. But gardeners can, and a degree of caution about what goes out and when, and about managing expectations after a cold snap, will make the transition into spring considerably less stressful.