What's the deal with NOT watering plants from above?

I don't mean to sound flip, but it's not like it rains from the ground up. And when it rains, it doesn't happen at the most opportune times of the day to prevent disease.

So why is it so important when watering plants to not get the foliage wet? And how is it different from rain?

This could be a very long answer, but for gardening purposes, i.e. potted plants, you water from the ground up to get the water to the roots. When it rains it doesn't always reach the roots either. Just like when you sprinkle.

You normally do not water your plants at night because they don't dry off and are more apt to get diseases. You cannot control the rain, but you can control when and how much and how you water your container plants.

Maybe you can get a scientist to give you a more detailed answer if you want one. But my short answer is that we gardeners try to give our plants all advantages to grow the best we can.

peony, yours is a thoughtful question and it makes all the sense in the world. We can't control rain, but we can control how we water. Since with some plants wet leaves are more prone to develop problems such as fungal infections, it's good to keep water off the leaves when we ourselves water to minimize that possibility, while at the same time realizing that if there is a particularly rainy season it's likely to happen anyway and we can't do anything about it.

Jnette, dp72: I have also been told (and it makes sense) that when watering from above during the day if drops of water are left on the leaves the sun light is actually intensified in that location and can cause damage (burning) to the leaf. The drops of water act as a magnifying glass lense and focus the light and heat into a very small area creating burnt spots on the leaves.

Both dp72 and gcorrier are correct - dp72's answer covers the best reason to avoid ADDING to the problems that rain can cause, and gcorrier's addresses the mistake of watering in full, hot sun. Actually, gcorrier, I wouldn't worry as much about spot burning a leaf as I would parboiling the whole doggone plant! I've seen vegetable gardens in Texas that looked like steamed spinach (and were!) after a mid-day watering session.

Thanks. I knew the people here would be able to answer that burning question for me. :)

So if I were to water from above (cuz sometimes it's very difficult to not get any leaves wet) watering in early morning would be least risky? I'd assume if I watered around 7 AM the water on the foliage would have time to evaporate before the sun hit it hard.

We don't get the relentless heat you have in Texas, but we can get a series of 90-degree scorchers in July and August. We actually had such a heatwave in April, which caused things to bloom faster. I hope that's not a sign of things to come this summer. My plants aren't the only things that wilt at 80 degrees.

Peony, you are so funny!
I have to say that, living in Texas, which is next door to h*ll, many is the time I've watered things in full, blazing sun to keep them ALIVE, and I've never had anything to "parboil" or had the magnifying glass phenomenon occur. To the contrary, they perk up and look great within an hour or two. I'm not denying the possibility of either, but there are times when a plant is so wilted it's going to croak if it's not watered THEN and so I think why not?

I've also read someplace (of course can't remember where, but I remember at the time I thought it seemed like a reliable source) that the water drops burning leaves thing wasn't really a problem. And I have on occasion watered in the middle of the day when the sun was beating down and have never seen sunburned leaves as a result. I think if the sun is that hot, the water evaporates quickly enough that it doesn't really have time to burn the leaves. Maybe things would be different in a more humid climate though. But there are other reasons not to water during the heat of the day because you'll tend to lose more to evaporation so regardless of what's true about the water droplets and the sun, it's better to do the early morning if you can.

See Peony8, I told you there were long answers. Now you know everything there is to know about watering. LOL

> (dp72) there are times when a plant is so wilted it's going to croak if it's not watered THEN and so I think why not?

That definitely makes sense. ("Croak", lol!)

> (ecrane3) I think if the sun is that hot, the water evaporates quickly enough that it doesn't really have time to burn the leaves. Maybe things would be different in a more humid climate though.

Yes, that makes sense, as well. We haven't hit that high humidity stage yet.

Does it take a full season for plants to establish themselves or just a few weeks?

> (ecrane3) But there are other reasons not to water during the heat of the day because you'll tend to lose more to evaporation so regardless of what's true about the water droplets and the sun, it's better to do the early morning if you can.

I did read about that at one point in my searching for too much information, lol. But if I forget, or if the weather suddenly changes wildly (expecting rain on a cloudy morning when suddenly at midday the blue sky opens up to a blazing sun), I'd probably run outside and water a wilting plant if I saw it happening.

I work at home only two days a week (sometimes just one), so I'll have to be vigilant about watering because I won't always be home to see my plants droop.

I ordered a water sensor, as well as Miracle-Gro Quick Start for the root systems. Anyone see a reason why I shouldn't use this fertilizer?

> (Jnette) I told you there were long answers. Now you know everything there is to know about watering. LOL

Hee! I'm one of those dorks who prefers to understand the science behind why things work. It helps with compliance. If, for example, I were to go on a diet, I'd want to know how the food I eat affects the interplay between various hormones, like insulin and cortisol. You can imagine the agony I put my parents through when, as a child, "Because I said so," held no weight with me. ;-)

I think another problem is that tap water is not the same as rain water. There are lots of things put into our tap water to make them safe for drinking. I would imagine this could cause problems that would not happen with rain. I have experienced the problem with brown spots from watering during the day. Onle certain plants are picky about this. Roses, Monarda, and Lilium stand out in my mind. Basically any plant that is prone to leaf diseases. I would rather water a plant that is going to croak in the middle of the day and have some leave damage than allow it to croak though. You can always use a soaker hose or leave a hose at the base on very very low. That is what I do.

That's a good point, Meredith79. I don't imagine plants appreciate chlorine and fluorine on their foliage unless they are tea leaves.

Let me add my name to the list of folks who have cooked plants when watering in sunny times - and I really should/do know better. Ivy, an otherwise way TOO hardy a plant, turned from green to brown crackle stage. Ivy should have never been planted, and it certainly didn't need the watering - but other plants in the area did. However, I was horrified when the leaves on ivy turned into potato chip types. No one else was affected because only the ivy was growing in direct sun.

Thanks, wannadanc. I will definitely keep that in mind. I have ivy growing on a chain-link fence to cover it and to shade the roots of other plants growing nearby.

So, soaker hose is the thing to use on all plants except the lawn. Is that the consensus? Even then it is best done in the morning before the sun gets hot to evaporate.

Seems like we have beat this dead horse enough. Just an old saying!

No, it's far from the consensus, but I agree that there won't be one, so let's do put this to rest.

Buy a water wand and that will really help with making sure things get watered below and not above.

I bought it for the roses but I use it for everything. It has a shut off valve which I love for moving from place to place and you can water deeply in a short amount of time. It is also long and eliminates some of the bending.

Believe me I would have put in an irrigation system if my DH would just let me go the Home Depot alone then disappear long enough to get it in the ground. I think next year I am going to try one in the raised bed.

If you can do it that would be wonderful. Everything does much better with a regular watering.

"You can imagine the agony I put my parents through when, as a child, "Because I said so," held no weight with me. ;-)"

Peony8, you have just described my son, and now (ha ha!) he has a son just like that. Wonderful children, VERY inquisitive and "need to know."