Frost is a major concern for nursery owners as it can damage plants and reduce stock, which ultimately leads to lost revenue. As such, it is essential to manage and prevent frost in all nurseries that experience frosty winters. In this article, we will discuss why frost damages plants and how growers can implement practical solutions to prevent and manage the negative effects thereof.
Why Does Frost Damage Plants?
Depending on the plant species, some can be damaged by cold temperatures well above freezing point, known as chilling injury. While others only suffer when temperatures fall below freezing, known as freezing injury. At which temperature a plant begins to suffer from either injury is heavily dependent on the plant species and how long they’re exposed to a given temperature. For example, some subtropical fruit plants will experience chilling injury at temperatures below 5 degrees Celsius, while temperate fruits such as plums will only suffer below temperatures of negative 1.5 degrees Celsius.
Plants suffer from frost damage because the liquids inside their cells freeze, and ice crystals form, which blocks water and nutrient uptake. It can also cause the plant cells to burst, resulting in damaged cells and reduced water and nutrient circulation. As a result, the plants dehydrate and wilt.
Adaptive Mechanisms to Protect Plants from Frost Damage
Plants already have adaptive mechanisms to protect themselves from frost damage. When temperatures start to decrease, the sugar concentrations within the plant cells increase, which, in turn, decreases the freezing point of the solutions within the cells. Furthermore, some plants produce frost-protective compounds called anthocyanins in response to cold temperatures. These compounds change the color of the plants to give them a reddish hue. This can be seen in species like Nandina domestica, Abelia grandiflora, and ornamental kale.
Preventive Measures to Avoid Frost Damage
There are a variety of methods that growers can consider implementing in their nurseries to prevent plants from suffering from frost damage. Here are some recommendations:
Production Cycle: Grow frost-tender plants in the summer months and more hardy plants in the cool winter months. This is especially true for annual species. This will also help improve turnaround in your nursery as many clients will not be looking for summer plans during the frosty winter times, and you do not want to be left sitting with unsold stock.
- Frost Nets: If you experience mild frost events and do not receive heavy winter snow, then you may be able to get away with simple frost nets. These nets are placed over the plants at night and are removed during the day when it starts to get warmer. They work by retaining the heat accumulated during the day and allowing it to recirculate around the plants throughout the night. When installing these nets, you can use a hoop system to drape the nets over. You must also ensure the nets are completely sealed at the bottom and that any nets of big holes are discarded. Keep the spacing between your plants tight. Closer plantings will retain heat better, but you will need to keep an eye out for any pathogens or pests that like dense plantings.
- Irrigation Timing: Early morning irrigations can help with frost, and well-watered soils retain heat better than dry soils. So make sure you keep your plants well-irrigated, even in the winter times. Do not let your plants experience any other stresses at this time.
- Fertilizer Schedule: Limit your nitrogen applications as autumn approaches, as it will encourage lush growth, which will only be more susceptible to frost in the winter. Phosphorus can be applied just before the cool season to encourage root growth, which will help the plants survive frost even if all the above-ground growth
- Another solution to consider is using heaters or heat lamps. These devices work by providing artificial heat to your plants, effectively raising the temperature in the area and preventing frost damage. It’s crucial to remember that these gadgets may be costly to run and might not be appropriate for bigger nurseries.
- Mulch may be used to help protect your plants from the cold in addition to heaters. Mulch is a layer of organic material applied to the soil, such as leaves or straw. This layer might help shield your plants from the effects of cold by retaining heat and moisture in the soil. Mulch may also aid in reducing weed development and soil erosion.
Finally, you may want to think about buying a greenhouse. A greenhouse is a building constructed of glass or plastic that is intended to retain heat and provide your plants a warm atmosphere. This may be a useful strategy for shielding your plants from the damaging effects of wind and rain as well as frost damage. The cost of constructing a greenhouse, however, makes it crucial to carefully assess if it is the best option for your nursery.
Frost damage can be a serious problem for nurseries, as it can lead to unsightly plants and lost revenue. However, there are a variety of practical solutions that growers can implement to prevent and manage the negative effects of frost. By choosing the right plant species, implementing irrigation and fertilization strategies, and using tools like frost nets, heaters, and mulch, growers can protect their plants and ensure that they thrive throughout the winter months.