The Importance of Water
Water builds the skeleton of plants
Something called Turgor, which is the cell in which water travels through to the stems and then the foliage, without water this is what makes the plant wilt.
Used for Photosynthesis
As water travels through the stem to the leaf, where photosynthesis is actually taking place water is evaporating through the leaves turning into Carbon Dioxide, which is vital for photosynthesis. The carbon dioxide replaces the position of the water in tiny holes of the plant's leaves, and photosynthesis begins! This is something that is only done while the sun is shining on the foliage.
Water delivers Nutrients
As water is traveling through the soil it is going into all the little air pockets and releasing and breaking up the nutrients that are in the soil from beneficial bacteria, worms, and organic matter. Keeping life in the soil alive!
When to Water
Always water in the morning, it is like breakfast for your plants! During the morning and at night the roots are most active, where during the day the activity in the plant is focused on the foliage. Photosynthesis is happening during the day as well as transpiration happening as the evening rolls in.
Transpiration is the secretion of water in the leaves, which is then turned into carbon dioxide for photosynthesis!
How to Water
For roots to expand and reach for vital nutrients and to keep oxygen within the root structure, the soil needs to be dried out a bit in between each set of waterings. The best way to water properly is by touching about an ¼ of an inch - an inch down in the soil. If it feels wet and the soil is nice and dark, wait to water until you touch it and the soil's top layer is dry and starting to crumble out.
Now, if in the morning you are checking and your leafy greens, in particular, are wet, but it's going to be over 90 degrees or a particularly windy day, no matter what. Water! Lettuce needs the extra moisture, by 2 in the afternoon you will be surprised to see your lettuce sadly wilting without the extra boost of moisture, especially if it is in the sun past 2 in the afternoon. The rest of your wall should be left to dry out for a day or so.
Example of overwatering. I have a brand new wall, with all new soil. And a freshwater basin with magnesium, nitro booster, and the eggshell all added to the water basin yet, my parsley is still deficient! I started to check to see if the soil was wet before watering with my finger, and stopped watering until it was nice and dry. Even if it was going to be a day over 90 degrees, I did not give my parsley water. The parsley ended up going through that drying period for the next 6 days with the temperatures probably averaging around 89 degrees. The plant was still plenty wet for those 6 days just sitting in the full sunlight each day until the soil crumbled out with a dry texture! The new growth is improving and my parsley is on the way to get in my belly! After the hard work of nursing this plant back to health, it's going to taste even better!
Another thing that can happen when there is overwatering is Powdery Mildew. This is a white powdery fungus substance that coats the leaf of your plants.
The moral of the story is that overwatering my plant was causing nutrients to wash away, choking and saturating the plant's roots to the point of a deficiency or death from rotting roots. Now that we are nearing fall with our nights staying cooler and even wetter with fog in certain regions, watering needs to be cut down. It's easy to just say water your plants every morning when it's almost 100 degrees out, but now it's time to check to see if the plants need the drink before delivering it to them. The chances of heat stress are diminishing while overwatering risk is rising.
Placement for Watering
As your walls grow in you will see each day as you water certain plants may need water while others don't. To assure you won't overwater or underwater you can pick and choose which set of plants go on each row. So that when you look at your wall in the morning to water you can choose to turn.
Tender plants like kale, lettuce, spinach, arugula, and chard can all go in one row because they can handle extra moisture and water. While the other row holds things like herbs, flowering plants, tomatoes, jalapenos, chives, basil, and mints! These plants like to dry out a bit between waterings for the best harvest results. The pots among your wall are going to be moving around here and there depending on their needs.