Re: why do young leaves turn brown when too much water is added to the plant

Leow,

You have asked about a phenomenon that has befuddled many novice gardeners: plants that get too much water look like they are not getting enough water. How can this be? The problem is at the roots. Like all tissues in the plant, the roots need air, specifically oxygen, to function properly. If the soil is too wet, there is not enough air in the soil for the roots, and they stop functioning. Despite being surrounded by water, they are unable to transport water to the rest of the plant. If they stay too wet for too long, they may start to rot, which further compromises their ability to transport water. From the leaves’ perspective, the problem is lack of water in both cases, too much water or too little. To the gardener, it looks like the plant doesn’t’ have enough water, and gives it some more!

The brown areas of the leaves are dead tissue. In this case, dead because they are not getting enough water from the roots, and have dried out. The young leaves may show the browning symptoms first for a couple of reasons. First of all, they are farther from the roots, so water has to travel farther to reach them. Second, young leaves have not yet had time to fully develop their means to avoid drying out by conserving water. Fully mature leaves have a waxy coating and other adaptations that allow them to tolerate water deficit better than young leaves do. However, any leaf will eventually die and turn brown if deprived of water.

Once brown areas appear, those areas cannot recover. The rest of the leaf may live on if conditions improve, but the dead areas won’t grow back.

Alex Brands