Adjust the temperature depending on cloud coverage

Leggy, tiny-stemmed plants in summertime are caused by a poor energy balance. As we saw in Step 1, pruning clusters to adjust the fruit load is a great way to mitigate this, but it is not enough. High summer temperatures, combined with lots of fruit, are very demanding in terms of energy. Plants need plenty of sunshine to produce the energy necessary to keep growing and bear a huge amount of fruit at the same time. (figure 1)

During a cloudy day, they do not have enough light. We need to keep the temperature as close as possible to 60°F all day and all night.

Warm temperatures force plants to grow. Without sunlight, they will only grow thin and weak. Cloudy days need cooler temperatures to mitigate weak growth. This way, plants can maintain their balance. It's that balance that ensures that they set a lot of fruit, while growing new clusters.

If you don't keep this balance, you’ll get a good harvest for a few weeks. Then, it will slow down until you reduce the fruit load, until the plant starts to grow back. But you will have lost a huge yield potential.

Here are target temperatures for different cloud coverage during summertime: