Split skins – outdoor pants
If your outdoor plants were rained on last weekend, there is a good chance that some of your toms have split skins.
You may wonder why a downpour of rain causes skins to split, given that the plants receive a good watering on a regular basis – usually more water than they get from a downpour of rain!
The reason is because transpiration stops, which prevents moisture loss through the leaves, but water uptake through the roots continues for a short period.
In other words…
When leaves become wet, they are unable to release moisture, but for a few hours, water is still absorbed by a plant’s roots.
This means that pressure builds up inside the plant and tomato skins split.
Pressure inside the plant returns to normal as a plant adjusts to wet leaves and roots reduce their uptake of moisture and nutrients.
Through wet periods, we often see leaves that look lighter in colour than they should be, especially in the early summer – as if they need a good feed!
The reason is often because, when wet, leaves cannot release moisture, so roots are unable to take in moisture and nutrients through their roots. Therefore, plants become nutrient deficient.
Fungal spores and blight
In August, we are trying to avoid blight – especially when it rains!
Wet leaves are vulnerable to fungal spores – especially if a plant is nutrient deficient
Because plants can become nutrient deficient (underfed) if their leaves have been wet for prolonged periods, their immune systems are also lowered with the result that plants will go down fast with blight or any other disease for that matter!
Indoor plants – greenhouse or polytunnel
Leaves release moisture because the air is dryer outside the leaf than inside and because of air movement – like the washing on the line dries faster in a breeze – I know because my wife told me!
A humid greenhouse will reduce transpiration (moisture loss through leaves) causing the same problems as faced by outside plants.
So it’s important to keep plenty of airflow and aeration in the greenhouse by opening the windows and doors too if necessary. It will also help avoid blossom end rot because the flow of calcium to the fruit won’t be interrupted.
There is a balance between humidity, airflow and transpiration
- The higher the humidity the lower the transpiration and water/nutrient uptake.
- The higher the airflow, the greater the transpiration.
- The greater the transpiration the higher the water/nutrient uptake.
The ideal …
- Low humidity
- Moderate, consistent airflow
- Moderate, consistent transpiration
- Moderate, consistent water/nutrient uptake
Imagine trying to achieve all that growing outside!!!
If we were growing in a high tech greenhouse, we could control all these issues. Of course growing in our modest circumstances means that we can’t. However, it’s good to be aware of these aspects that effect the growth of our plants and tomatoes.
I hope all is well in your tomato garden!