Water is the hardest element for a gardener to get right

I have been gardening longer than I care to admit. I'm  certainly not an expert, but I've learned a lot, and have enjoyed growing lots of veggies, fruit, herbs and flowers, through the years.
I still feel like I struggle with watering.  Water to much the leaves wilt. Water to little the leaves wilt. Wait what, which is it? The plants are trying to tell you something is wrong, but the symptoms are often confusing.
It's not just me ( thank goodness) I can't tell you how many times people come to my work ( a Co-op with a garden center) and think they need calcium because they have blossoms end rot on their tomatoes. The reality is, its pretty uncommon for clay soil, which most people in my area have to be lacking in calcium. The problem is a watering problem most of the time.
Quite often the fix to a garden problem is water, more or less depending on the problem.
I feel kind of silly, but I have started to use a water meter. My rough and dry gardeners hands don't seem to tell my brain if the soil feels moist or not. So I'm using the meter I bought a long time ago.  I hope it will help, because I'm relatively sure I have been over watering. Most everything is thriving, but when one of my tomatoes started to die, I decided it may be to much water. I have been watering most plants less, and everything is looking a little healthier, and growing a little faster. It could be a coincidence, because summer is in high gear, so I will have to wait and see.
I just wanted to share this, because it's such a easy thing to get wrong, and makes such a large impact.

I think using a meter is a great method. Are you using a rain gauge style, where it just fills with water to tell you how much fell? Or are you using the moisture meter kind where you stick it in the soil to get an idea of how wet/dry it is?

And you already know this, but for future readers, I highly recommend mulch. It really helps for those times when we over water or under water. The good kind of mulch can be a buffer.  

I know you didn't mean to, but you gave me a little chuckle. I live in N. California. We get almost no rain for the summer months. I have a moisturizer meter, the kind you stick in the soil. It should take some of the guess work out of the equation.
Mulch, mulch, mulch, that is always my advice too. Mostly I use living mulch. It works great, except in the beginning of the growing season, before it's had a chance to cover the soil. I have been trying shredded cardboard as mulch. It's early yet, but so far I'm happy with it.  I have also been using chop and drop with borage. That's not great, because it brakes down quite fast.
I also like ollas. I only used 2 this year. I need to use more in the future.
Thanks for the help it's appreciated

You didn't mention all the other indicators?  Yellowing leaves, yellowing leaves with green veins, yellowing leaves turning white, leaves getting mushy, leaves getting dull green and crisp, leaf drop, drooping leaves, crinkled leaves, etc just to list a few.  Plants will talk to you and show you what is wrong if you learn to listen.  Suggest picking something cheap and easy to grow and deliberately torture it various ways to learn how it reacts to a bad green thumb.

Over watering is as big a problem as under watering. My climate is almost always excess rainfall, which is lovely but can lead to anaerobic soil and nutrient leaching. Here is the water puddling in one of my berry areas after rain.

excessive water

I'm now using unedged raised beds for my vegetables and berries, and trying to increase my soil organic matter content (depleted by 100 years of ploughing). I'm also thinking that biochar is a good solution - it acts as a sponge holding the water and slowly releasing it as the soil dries out.

Jen Fulkerson wrote:I know you didn't mean to, but you gave me a little chuckle. I live in N. California. We get almost no rain for the summer months. I have a moisturizer meter, the kind you stick in the soil. It should take some of the guess work out of the equation.

Haha! Yeah, I guess a rain gauge wouldn't be much help for you would it? :) I completely forgot to look at where you are located before answering that.