I never get too concerned about these little details. I think if you enrich your soil well with compost and get those worms working they will aerate it and help any soil drain unless it's at the bottom of a slope. I think if you water deeply and the next day all the plants are wilting you definitely need more OM unless you are living in the Sahara. Adding OM is a regular part of gardening effectively.

I've never had plant roots rot in my garden altho I'm stingy with water as I want the roots to go deep. I only water when the perennial sunflowers and maltese cross start to wilt. They are more sensitive than others and they warn me when it's too dry. Then I water thoroughly. They bounce back really quickly when watered.

I don't even get too interested in whether most plants like some sun/some shade/etc. I just put them in the garden where I want them, they are going to be shaded by other plants at some time of the day anyhow. If they don't do well I'll move them. Might be different if I lived in the deep south but in a northern garden it seldom gets too hot that plants suffer.

I think gardening should be fun not something that has too many rules. Feed the soil and the plants will be happy.

'Evenly moist' soil just describes soil that doesn't dry out excessively. Root rots only occur if the soil is excessively moist for periods of time - if you dig down into teh soil and water immediately fills the hole or if you are able to squeeze water out of a handful of soil. Generally, any organic matter with some decent texture - like compost - will help to improve drainage. It also assists in retaining moisture so that when you irrigate, the water doesn't dissipate immediately.

Although it sounds like an oxymoron, "well drained but evenly moist soil" is really just soil that maintains a proper amount of organic matter. Applying a good layer of mulch on top of the soil will also help to keep the soil 'evenly moist' as it prevents evaporation.

Before you go off the deep-end, do some reading on "what is compost" and "what does compost do for my soil"...
Given that organic matter will improve soil's ability to retain moisture, you can see that whatever, however you improve the soil with organic material will only help your soil with its moisture and will also nourish it.
Compost should not be thought of as a fertilizer...but in many cases, it can be used in place of.

Organic means anything natural.
Non-organic is man-made.

Soils should drain well so that excess moisture doesn't hang around roots....like you said, too long it will rot the roots.
As far as some plants requiring its soil to be kept evenly moist, that is your job....watering when needed and taking steps to help the soil retain moisture longer.

Read about using peat moss and what it does for soil.

By the way, if you can, begin a compost pile. For info ask the the question "how can I build a compost pile"?There are probably a hundred or so messages about this subject in this journal.

Soil is composed of minerals, clays, and sand particles. Living in among that mix are bazillions of bacteria, fungi, protozoa, and microscopic insects. Your soil's drainage depends largely on the healthy population of these microbes.

If you think you need more of those microbes, you can apply compost. It is full of microbes just waiting to be washed down into the soil. If you want to feed the microbes you have, you can apply something like organic fertilizer which is made up of corn meal, alfalfa, soy, cottonseed, and various other ground up beans, nuts, and seeds. Or you can go to the feed store and buy those materials in 50-pound bags for about 1/6 the cost of the organic fertilizer. When the microbes are well fed and watered they grow in size and population to soften and improve the soil's drainage.

Plants cannot uptake any nutrients from the soil if there is no moisture there to move those nutrients, so an evenly moist soil is one that contains some moisture, not a lot, so those nutrients can move. A soil that is wet will also hinder the movement of nutrients because the plants roots also need some air, which too much moisture will replace, to get those nutrients into the plants. An evenly moist soil is one where if you take a handfull and squeeze it tightly it will ball up but if you poke it with a finger it will fall apart, a good, workable soil.
Well drained means that water will move out of that soil in a timely manner, excess water will not stay in the soil excluding air for very long. Many soils that lack sufficient levels of organic matter will either not drain well at all, holding water in the soil for days, or will drain too quickly, in less than an hour or two, and then will appear and feel dry.
In sandy soils organic matter will hold both moisture and nutrients in the soil and in clay soils that same organic matter will open up the soil so excess eater drains away adn the nutrients that often get tightly locked onto the caly soil particles are released for the plants to use.

Okay, first of all, I want to know: if it says a plant likes "evenly moist" soil, will a "well-drained soil" be alright??

A soil will drain water for some time after watering or a rain. The soil can then be said to be evenly moist. The proper description of the soil water at this time, when gravity has drained the free water out, is "field capacity."

Plants will uptake water until the plants can no longer draw water from the soil. The soil is now at the "wilting point." After the wilting point, the plant wilts and dies. What is the probability that the soil is still evenly moist? I does not have as much water as at field capacity but it may still evenly moist.

I would say that the term "evenly moist" is not very helpful.

The addition of organic matter is very helpful because it helps drainage and it improves the soil's water holding capacity. So adding organic matter to your soil is good.

This of course assumes that there is good drainage under the soil.

Thank you all for your helpful advice. The reason I'm concerned is because I'd like to grow two different plants that seem to have very differend needs as far as water is concerned. One is monarda, which seems to like the soil more on the moist side, and the other is agastache, which, if you've ever grown, absolutely demands a well-drained soil. Anyways, what I'm wondering is: is it possible to have a soil that meets the demands of both of these plants? They're both absolutely gorgeous, but together I think they would look even better.

You can grow these together in a soil well endowed with organic matter that does stay evenly moist (not that difficult to see) but that drains well. That is a good description of a good soil and is not all that difficult to understand.

You can grow these together in a soil well endowed with organic matter that does stay evenly moist (not that difficult to see) but that drains well. That is a good description of a good soil and is not all that difficult to understand.

This may come as a complete shock to some, but I totally agree with this statement!! A soil with sufficient organic matter will stay evenly moist but will also provide adequate drainage and this is a growing condition that the vast majority of plants will prefer.