Return to the Professional Gardener Forum | Post a Follow-Up

 o
water drains too fast

Posted by jvmagic USDA9 (My Page) on
Tue, Aug 26, 08 at 10:55

I purchased some pots, potting soil, and plants from Orchard Supply and have noticed that when I water, it drains very fast and comes out of the bottom of the pot. I have also added draining rock on all my pots.

any advice?


Follow-Up Postings:

 o
RE: water drains too fast

The most likely problem is that the soil ball is not moist. Place the pot in a bucket/sink and fill half full, or more with water. The pot will more than likely float which mean the root ball/potting soil is not holding maximum water. When the pot sinks let is soak for half hour, remove and allow to drain. If you have the problem again, repeat the procedure.


 o
RE: water drains too fast

That could be, but it also could be you have a sharp draining medium. I sometimes order that type of mix specifically when transplanting certain stock needing exceptional drainage. One is a coir based mix, as opposed to peat.


 o
RE: water drains too fast

  • Posted by bboy z8 WA USA (My Page) on
    Tue, Sep 9, 08 at 12:15

Take out the draining rock, in small containers it actually impedes drainage by causing the water to back up when it hits the different texture of the rock layer.

In big planters with wide flat bottoms a rock layer is used to move the water sideways to the drain holes or slits. It still backs up before hitting the rock layer, but in such a situation getting it out of the bottom of the planter after it saturates the bottom of the soil column and then rushes through the rock layer becomes the priority.


 o
RE: water drains too fast

Gravity forces water down between the soil particles, like any other molecule, and is stopped ,held back, by impermeable material. The last time I checked, rocks of any size are much more permeable than potting soil.


 o
RE: water drains too fast

Technically, the flow of water is slowed down when there is an abrupt change in pore size. This is counter-intuitive initially, but it is true. A layer of rock beneath finer soil will slow down the downwards flow of water, as the finer soil has a stronger "hold" onto the water than the rock does (due to its finer particle size, I believe). When there is enough water, the gravitation pull will eventually overcome the hold that the finer soil has on the water and will pull it through the rock.

- Audric


 o
RE: water drains too fast

The water "held" by the soil particles is do to the polarity of the molecules and is called hydgroscopic water. This is the water that is used by the plants. The water that is not "held" to the soil is called gravitational water and CAN NOT be held to the soil particles in any fashion, thus "falling" through the soil. This procedure dose not have anything to do with "... an abrupt change in pore size." going from smaller to larger although, as I previously stated, does occur going from larger to smaller pore sizes.


 o
RE: water drains too fast

Hydroscopic water is held tightly to the soil particles and is not the water available for plant use. The plant available water is made up of the water content of the soil between the Field capacity (when free drainage has stopped) and the wilting point (when all that is left is hydroscopic water).

Going from smaller from larger does slow down the downward movement of water. Refer to the article linked below and the images on page 3 of the .pdf (p. 25 in the article).

Quote and image below both from the article linked.

"Any change in soil porosity encountered by a wetting front affects water movement... the relatively small number of contacts between the aggregates limits the amount of water that actually moves through this layer. Only when the soil is nearly saturated does the water move rapidly through."

"Water Movement in Soils by Dr. Walter H. Gardner"


 o
RE: water drains too fast

  • Posted by bboy z8 WA USA (My Page) on
    Tue, Sep 16, 08 at 18:02

>Only when the soil is nearly saturated does the water move rapidly through<

and rushes out the drain hole, producing the false impression of enhanced drainage being given by the use of the so-called drainage layer in the bottom of the pot.


 o
RE: water drains too fast

I didn't find anyone addressing when the water runs straight through the soil in the pot because the soil won't hold it. Im looking for help how to augment our soil in our containers. Our soil doesnt seem to retain any moisture so Im watering daily and my plants (dahlias, cannas, elephant ears) are wilting and peaked. My dahlias, especially, are losing leaves (yellowing and drying) at bottom of stalk and havent gained any height in 3-4 weeks. We were excited how voraciously everything was growing and expected to see blooms a lot earlier (we had been planting tubers in early May in years past, but started them all in early April this year). Its only the beginning of July, but weve had a hellish month of hot, hot, hot days and little to no rain through June here in the Baltimore area.

Is there anything we can add to the established pots (plants are on an average 24-36" high) without emptying the pots completely? If it is too late for this years blooms, what should we add this fall when we empty the pots into the compost pile (yes, to be reused next year)?


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Professional Gardener Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here