I don't know about the plants but I'm sweating
every time
I walk in the garden.
It could just be humidity. I don't care what the weather
says it's like 100 north of a beach here lately.

Hi E.,

You are very observant.

When plants 'sweat', it is known as transpiration. (When humans do it, it is known as 'perspiration'. lol) In plants, transpiration is a natural part of the process of photosynthesis. Most of the time, transpiration is a good thing.

Transpiration is just the evaportation of moisture from the leaves of the plant. It occurs when a plant is conducting photosynthesis. The stomata of the leaves are open to allow the passage of CO2 and O2, and the water passes out of the stomato at the same time. As long as your relative humidity is lower than 100%, the air will dry the transpiration off the leaves. This is known, of course, as evaporation. Is evaporation the end of the process? Not quite.

Plants, of course, need moisture, so they have to have a way to replace the moisture they lose via transpiration. So, to replace the water lost from their leaves, the roots of the plant take up more moisture from the ground. At the same time they are taking up water, they also take up minerals, which they use as nutrients. The plant uses the minerals as food, the moisture moves through the plant and is part of the process of photosynthesis and, at the right time, some of the moisture transpires out of the leaves and evaporates. It is an ongoing process.

Where plants run into trouble is when there is a lack of available moisture in the soil and the roots cannot find any water to take up to serve as a replacement for the water that has transpired through the leaves. When there is no water available, the leaves wilt. A little wilting on a hot day can be normal, even with moist soil. It just means the plants are transpiring moisture out of their leaves faster than their plants can take up more moisture from the soil or that there is no moisture in the soil for uptake. However, with each plant there is a certain wilt point that it reaches from which it cannot recover and leaves or even the whole plant die. That's why we try to keep an even, steady supply of moisture in the soil for plants.....to prevent excessive wilting following transpirtation.

Make sense?

Dawn

Dawn,

Thank you! That made perfect sense! Are you a horticulturalist? Youre very smart. I'm glad this is a good thing, I do know my plants doubled in size in the 5 days I was gone. And they are really branching out and have great color. Now I'm praying for fruit and against blossom drop...

I hope I'm watering my 6-pack ok. I'm just checking the soil about 1" down every 3 days or so and if it is drying out I give them a drink. I may have to do it every 2 days in this heat, but so far I am only watering every 5 days.

It is 94 in the shade here right now. My outdoor thermometer is on my back porch where the sun never reaches it.

Way hot. And humid. I don't expect this till July...

Thanks again Dawn. Much appreciated.

E., Nope, I hate to disappoint you but I am not a horticulturalist. Not even close. Just like my daddy and his daddy before him, I'm just an ordinary old dirt farmer....and I an not a professional farmer, just a hobby gardener. If you garden long enough (and I've done it all my life), you learn a little bit here and a little bit there and eventually it all adds up.

When I first saw the title of your thread, I was afraid you were going to describe symptoms of edema, so I'm relieved it was just transpiration.

At the present time, it is 96 degrees in the shade on our east-facing front porch. That is too hot for early June. I think much of Oklahoma is running 10-15 degrees hotter than "normal" (as if we really have any idea at all what normal weather is) for this early in June. It sure makes you wonder what the rest of the summer will be like. I'm worried we're headed for record heat. If it is like this now, then I do indeed wonder what it will feel like in July. I lasted outside this morning until 11:05 a.m. and when I came inside it was 91 degrees.

Still, we have to count our blessings, don't we? There are a lot of gardeners in the south who have no homes, yards or gardens left. There are more long the mighty Mississippi and other river basins whose homes, yards and gardens are under water. By comparison, we've got it fairly good even if it is way too hot and too humid.

Water them whenever they need it. You're doing fine as long as you're checking the soil and making sure it feels dry before you water.

At this time of year, a healthy tomato plant can grow an inch a day as long as it has adequate nutrition and water. That's how the little transplants we put into the ground in April become towering monsters by mid-June. As long as your plants are growing and healthy, all you need is a little cooperation from the temperatures and you'll have fruit. So, let's hope the nights cool off enough to allow fruitset to continue for a while longer yet.

Dawn