About this time of year, after tree tubes have been on seedlings for a month or two and the weather has started to heat up, I start to hear two questions.
Will my seedlings overheat in Tree Tubes? The answer is absolutely, unequivocally: No! Tree tubes dramatically reduce the heat and moisture stress on the seedlings inside. There is no case where seedlings would ever “overheat” in tree tubes as compared to un-tubed seedlings.
Case in point: Tuesday here in southern Minnesota it was 100 degrees with a steady 25mph wind.
Part of the misconception that seedlings might overheat in tree tubes is due to a misunderstanding of how temperature is measured and experienced. What has happened many times is that folks drop a thermometer down a tree tube to get the temperature inside. It might be as high as 110 degrees. Then they this very high temperature to the ambient temperature. However, ambient temperature is recorded in a weather box, with the thermometer sensor shielded from the sun but exposed – through louvered blinds – to air movement. Tree tubes reduce the amount of solar radiation incident on the leaves. If you measured the temperature of a leaf in the full sun you’d find that it is much higher than the temperature of a leaf in a tree tube.
Add to that the fact that seedlings are under less moisture stress in tree tubes, and you see that they are cooler, more moist, and happier in tree tubes – no matter how hot it is.
Another question I’m asked is about leaves – or parts of leaves – turn black in the tree tubes. This is very normal, and it’s no problem. Often there is a steady stream of condensed water droplets dripping down the inner walls of the tubes, back into the soil. Leaves that are pressed against the walls of the tube are constantly bathed in this water. This can cause the wet part of the leave to brown or blacken. It’s no problem at all. The tree is growing so fast it quickly replaces any lost leaves.
If you have any other tree tube questions, please don’t hesitate to contact us!