Soil Drainage

Download PDF

Yesterday I gave a class at the Theodore Payne Foundation on Easy Care for a Native Plant Garden. (As promised I am posting the powerpoint in the presentation section of my website.) Soil drainage was a topic covered in the class. In preparation I performed a standard soil drainage test in my yard. I dug several holes, approximately 10 inches deep and 8 inches wide, in several locations. I filled the holes with water, allowed them to drain, and repeated measuring the water level at the start and then in fifteen minutes intervals. My soil drained very quickly – approximately 2 inches in 15 minutes.


Originally I gave numbers to define, slow, medium, and fast-draining soil in the presentation. I had checked several websites and books for the numbers and came up with the following.


  • less than 6/hr = slow
  • 1 – 6 in/hr = medium
  • greater than 6 in/hr = very fast

Although I had never thought of my soil as draining excessively fast, at 8 inches/hr. it was considered by most as such. It does drain well, but it is quite loamy and stays wet for a long time.

I decided to check more websites for numbers. They come out all over the place.

Guidelines for Soil Drainage Test from the Web
Slow – Less than ½ in./hr
Medium – 1 to 4 in./hr
Fast – Greater than 4 in./hr
Poorly drained – Less than ½ in./hr
Moderately well drained – ½ to 1 in./hr
Well drained – Greater than 4 in./hr
Too slow – Less than 1 in./hr
Well-draining garden soil– 1 to 2 in./hr
Too fast – Greater than 4-8 in./hr
Poor – Less than 4 in./hr
Moderate – 4 to 8 in./hr
Excessive – Greater than 8 in./hr
Poor – Less than 1 in./hr (over 8 hours for hole to drain – poor soil drainage)
Well-drained – 1 in./hr
Excessive – Greater than 1 in./hr
Poor – 3 in. or less/day (24 hrs.)
Adequate drainage– 6 in./day
Very good drainage – 12 in./day

It is true that most called for holes that are 12 inches deep, and one, the last one, called for a 2 ft. deep hole. Still the numbers are quite scattered.

Never being a stickler for exact numbers when it comes to gardening I modified the guidelines on my presentation to be the following:


Dig a hole, fill it once, fill it again and measure level change in fifteen minute increments.

  • takes all day to drain = slow
  • less than a day, more than minutes= medium
  • drains in minutes = very fast

I’m happy with this, but thought I’d throw it out to all of you very knowledgeable gardeners.

How do you define slow, medium, and fast soil drainage?

Last Modified on March 24, 2015
This entry was posted in Uncategorized
Tagged with
Bookmark this article Soil Drainage

4 thoughts on “Soil Drainage

  1. Hi!<br /><br />I saw you were mentioned by Horticulture<br /><br />Yay! <br /><br />And while reconstructing a deck, too.<br /><br />:)<br /><br />Becca

  2. Hi Becca – thanks so much for letting me know about this. It made my day!

  3. Anonymous

    Hi Barbara,<br />Fast-less than an hour-you can see it moving!<br />Medium-anywhere from 1 hour to 3 hours<br />Sloooow-4 hours or more.<br />Of course, this is not scientific. Good to note that even within a garden&#39;s boundries there can be great variation especially when you have created small berms and hills or other raised planters.<br />Best-Dan

  4. Dan – sounds good to me!

Comments are closed.