Tabasco wrote:I've been going round and round the web on this subject.
I would reason that there are so many seemingly conflicting answers, because there are equally as many scenarios. None are completely wrong (except perhaps, overhead sprinkling at night when it's raining and humid) but not all will be right for every situation.
You need to consider moisture holding capacity of your soil, what type of container or in-ground, temperature, humidity, winds, needs of the plant, Containers will dry out quickly. Sandy soil can't retain a lot of moisture. High humidity increases risk of disease. Hot dry winds increase evaporation. Heavy feeders will be stressed if forced to go without water for too long. Some plants, like peppers, do better when a little stressed for water. If you're using drip irrigation, you don't have to worry about wet leaves, and if you mulch (you mulch, don't you?) then the evaporation from the top of the soil will be a lot less and you will always be delivering the water directly to the root zone.
So, in a perfect world, you want to know the point where the soil is no longer holding moisture that the plant can access, and then you want to replenish that moisture, without letting the plant sit in a puddle. Go back to weather, temp, soil type. You may need to walk the garden several times a day poking your fingers down in the soil, before watering and afterwards. Observing any wilting of the plants. A little bit of wilt in the heat of the day is okay. Does the plant recover in the evening, or at least by morning? Is the soil dry by afternoon? Do you have hot winds blowing at 30mph every evening for 3 hours? (I had to sign a disclosure when I bought my house that it does that here!)
Here are 2 very technical articles (mostly about corn, but you can extrapolate) about optimum water content for maximum yield. Me, I just don't want them to wilt and be mad at me.
SOIL, WATER, AND CROP CHARACTERISTICS IMPORTANT TO IRRIGATION SCHEDULING
https://www.bae.ncsu.edu/programs/extens ... 452-1.html
IRRIGATION SCHEDULING TO IMPROVE WATER- AND ENERGY-USE EFFICIENCIES
https://www.bae.ncsu.edu/programs/extens ... 452-4.html
This article is mostly about lawns, but it makes a good point:
"It is also important to reduce your irrigation frequency. As mentioned previously, disease pressure is increased more by routine irrigations that apply more water than is required.
If your irrigation system utilizes subsurface irrigation (subsurface drip irrigation, or buried drip lines) the issue of irrigating at night or early morning is not important because water is delivered directly to the root zone and therefore no water is present above the soil surface on above ground plant tissue.
Landscape Irrigation Management Part 5: Irrigation Time of Day
https://www.clemson.edu/extension/hgic/p ... c1804.html
I'm in the desert. We water with drip and a few select mini sprayers in the morning (primary watering) before sunrise. Just before sunset, they get a little drink as well. We're on that schedule now, because that's when the soil no longer feels moist 2" below the drip emitters. 6 weeks ago, we watered every 3-4 days at 10am because I didn't want to put ice water on plants in 45 degree temps. The only things that we use sprayers for are open areas with newly sown seeds close to the surface and some groundcover areas. Everything else is drip, buried under mulch. The surface barely gets moist, ever. The schedules get adjusted based on what the soil feels like and what the plants say by their appearance. In high summer, mid afternoon, I give small pots an extra splash with the watering can as well. Your mileage may vary.