The amount of chilling units vary depending on the plant. Chilling units are worked out by how long the plant is at or below a certain temperature. For example, our strawberries require 30 -35 units. In an ideal situation, the plants would receive all their chilling units in 30 – 35 days with temperature being less than 7 degrees Celsius. However, we aren’t guaranteed those temperature, so night-break treatment enables the plants to receive the chill units.
Two nights of light break treatment (on for 10 minutes every hour for 10 hours) is equivalent to 1 chilling unit.
Where grow development and physical activity are temporarily stopped. This means the plants are not using energy, almost like a bear during winter.
All strawberries were Alpine or woodland grown until the mid 1700’s. These berries were very small but extremely sweet and full of flavour. Typically, winters would be cold and the plants would be completely exposed to temperatures below 0 degrees.
The cycle of strawberries growing in the wild would be as follows:
- Plant flowers and produced fruit late spring to early summer.
- the plant then enters dormancy through the autumn.
- Cold winters break the dormancy.
- The plant then wakes up quickly, ready to produce lots of flowers and therefore strawberries. This quick awakening enables the plants to use MOST of its energy in producing fruit. Rather than using more energy waking up.
Here in Cornwall we don’t experience cold winters like they do in the mountains. So, to break the dormancy of the plants sooner and top give them enough chilling units, we provide night-break treatment.
If we didn’t provide night-break treatment, the plants would still ‘wake’ from dormancy, but it would be slower. Think of night break treatment like caffeine. Without caffeine we can be groggy and slow to start, but after a cup of coffee you tend to feel more alive and ready to start your day*. This is a similar situation for the strawberries receiving night break treatment.
*Please note, no scientific research was involved with caffeine, we are just speaking from experience.
Night-break treatment benefits our plants in several ways. Some of which include: stronger plants, bigger crows which results in more flowers which in turn means more strawberries. We use incandescent lighting which is the old fashioned light bulbs!
If light treatment in horticulture is of interest to you, can you find out more by clicking here.