Hello! First, I would recommend going to MIGardener.com and subscribe to their weekly newsletter, Grow Big. They are very knowledgeable on gardening.
When is the best time of the day to water?
Starting somewhere in the middle of the day, you don't want to water in the heat of the day?
Why?
There's an interesting phenomena that takes place with the soil - it heats up the water and the heat can damage the roots of the plant.
Water on the leaves can cause sunburn on the leaves. See, when the water is on the leaves, it acts like a magnifying glass which will condense the sunlight and it's heat on the leaf and burn them. If you see discoloration on the leaves, chances are it's because there's been water left on them during the day.
What about watering at night?
This isn't always the best time either. Water sitting on the leaves can attract mildew and disease. You might see a powdery mildew on the leaves and this is from water sitting on the leaves in the evening and night.
When it's hot outside and you water in the night, the mildew loves the water on the leaves and so multiplies itself.
Blight is one disease that can happen from too much water sitting on the leaves. Blight is a mold that can thrive from water left on the leaves.
So, when is the best time to water?
The answer is, in the morning. It's at this time that the water can penetrate the soil and feed the roots.
The best time is from 5:30 am to 10:00 am.
During this time, the plants have the best chance to use the water and the leaves have a chance to dry out.
Here's the basic theory - The leaves have the mouth and lungs of the plant. Bringing in carbon dioxide, plus the sunlight, creates food for the plant resulting in a discharge of oxygen in the air.
When you water in the morning, the water has the best chance of getting into the roots and into the plant so it can get through the day and finish it's process when it puts out the oxygen at night.
Hope this helps. There's plenty of opinions out there about watering that I read, but for me, this made a lot of sense.
Let me know what you think. You can email me at doug@pocketbloomers.com and I will answer you as quickly as I can.
Take care and happy gardening!
Doug Daniloff, Pocket Bloomers, LLC