The recent cold temperatures were a grim reminder that winter still has powerful influence over our weather and our landscapes. Luckily, most of the emerging plant material seemed to have survived quite nicely. Nevertheless, with the chance of more cool nights still ahead, here is what you can expect if the thermometer drops below freezing again.

Because of the sugars and other cellular constituents, most garden crops will not experience freezing injury until temperatures drop to about 30 degrees. However, cool-season crops can usually experience temperatures in the low 20s without serious injury. Within species, there can be some difference in cold susceptibility. For example, romaine lettuce can withstand temperatures 3 to 4 degrees colder than leaf lettuce.

Plants that have been acclimated to the cold can stand lower temperatures than those that have been recently moved outside from the warm house or greenhouse. As plants get larger, they usually can withstand colder temperatures than very young seedlings. A particular vulnerable stage is just as seedlings are emerging from the soil.

When cold injury does occur, the damage may be to the outside of the leaf while the center of the leaf and stem is uninjured. Do not be too quick to replant if you suspect cold damage has occurred. With slight damage, plants will send out new leaves to replace damaged tissues quickly, so you are better off not to replace the plants.

However, if the main stem is injured or leaf injury is severe, replanting might be best. Fortunately, freezing injury symptoms are visible quickly, and tissues that are injured turn limp.

The impact of below freezing temperatures on the lawn is very different. There should not be anything to worry about. Cooler weather may slow down growth for a short while, but turf damage is highly unlikely. Cool-season grasses like tall fescue and Kentucky bluegrass will not be affected by the cool weather. So, do not worry about that flush of nice green growth we enjoyed the past couple of weeks. Sustained freezing temperatures may damage warm-season turfgrasses but only if they have significantly started their spring green-up. Most warm-season grasses around here are not quite there yet, so the timing of a brief cold snap is not likely to harm them.

Fruit growers often wonder at what temperature fruit buds are killed. Because many growers experience different conditions at night, we can only speak in general terms. Generally, the further along in the bloom stage the plant is, the more cold sensitive the blossoms are.

Remember the actual damage will be influenced by the weather before the temperature drop. An extended warm spell before the cold snap may result in more damage due to a loss in cold hardiness. For apples pears, plums, prunes, and cherries, temperatures in the mid-20s during blooming can cause up to 90 percent crop loss.

— Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.