One modification to provide the best possible balance is to find catch-saucers or catch-pans into which the planters will fit. Then, add more drainage holes in the bottoms of the containers. During these crazy rain events, your plants are going to be saturated no matter how you package them. But when the rain stops, you could lift the planters, dump the catch-pans, and set the planters back. For normal watering, the catch-pans will hold water that drains too quickly but keep it in contact with the soil (through the drainage holes). The soil will act as a wick and draw water back in from the pan until the soil is saturated. This is how I water my house plants, and it works reliably.

If you don’t mind precision hand-watering, then drainage holes at the soil’s surface would certainly reduce the overflow from the top of the planter… but it won’t change the saturation of the soil. In a long-term rain event, some water will run out those holes when the rain starts. However, it won’t take long for the soil to become saturated up to the drainage holes.

I’m not sure what’s causing the 2 or 3 that don’t drain well. If I had to guess I’d say the soil is probably packed too tightly, but it’s the same type of soil (specifically for vegetables) that I used in all my planters. I have tried using a screwdriver to clear the holes in case something was blocking them but no luck. I’d like to find a solution using the existing soil/planter so I don’t potentially damage the existing plants in them.

As far as drainage speed, I believe it is ok for normal rainfall, but the problem is it’s been raining here for several days straight so the planters just stay full of water (just like you experienced). Ideally I’d like to keep the drainage speed as is for normal watering/rainfall, but have sort of an “emergency” drainage for the weather we’re having now. I’m afraid if I drill more holes at the bottom, the normal watering will drain much too fast. That’s the reason I thought of the drain holes just above the soil line. I suppose I could devise a stopper of some kind.

A few thoughts: If rain temporarily fills your planters without disturbing the contents (other than making them wet), you don’t have a problem as long as the planters drain when the rain stops. If the standing water is gone three-to-six hours after a storm, the planters are draining as well as many fine planting beds.

Two good reasons to improve drainage: 1. The accumulating water actually moves stuff around in your planter: things float; soil washes away; seeds get moved around; soil (some potting soils will do this) becomes suspended, making a slurry rather than a firm growth medium. 2. The only way water seems to leave the planter is through transpiration of the plants, and evaporation from the surface of the soil. In this case, you’ll have standing water for days after a heavy rain, and most plants will die.

In the case of stuff moving around, sometimes no amount of drainage will help; add water too quickly, and bad stuff happens. I suppose above-the-soil-line holes would help in this case. However, I’d rather see water drain lower in the container, so I’d consider a few things: Why are the existing drainage holes not working well? Can you open them up better by pushing something in from underneath? Is the soil bound too tightly so it doesn’t let water through efficiently? Maybe starting again with a fresh, different potting mix will solve your problems? Finally, I’d add more drainage holes either in the bottoms of the containers, or very low on the sides.

If the water simply doesn’t drain-even several hours after rain stops, it’s imperative that you improve the drainage. Again, are the bottom drainage holes letting water out? If not, either clear what’s blocking them or add more holes. I’ve relied on holes that are no more than razor slits, and they’ve been fine. When a container with such holes gets overfull with water, it takes a half hour or so to drain, but it does drain… and that’s good enough. Actually, I prefer a slower drainage rate because it means I don’t have to water as frequently during dry weather.

Oh, here’s why I don’t care for the idea of drainage holes above the soil line: When I’m doing the watering (as opposed to rain), and the planter is well-established, I like that I can fill the space between the top of the soil and the top of the planter with water and let it soak in at its own pace… I don’t have to stand there and add slowly as water gets absorbed. Without the catch basin effect, hand watering requires more attention and more time.

Best of luck.

http://www.flickr.com/photos/monkeysmumsie/3540207418/in/set-72157618364347186/

Those are some of the pictures if you want to see how they look

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