En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
11 ratings

Tuesday - February 19, 2008

From: Bennington, NE
Region: Midwest
Topic: Seed and Plant Sources, Soils
Title: Difference in natural soil and potting soil.
Answered by: Nan Hampton

QUESTION:

If you buy store bought soil is it different than soil from the ground?

ANSWER:

Soil from the ground, or natural soil, is composed of finely ground rock (mineral component) and humus (organic material). One way to classify soils is by their texture. The basic texture of soil depends on the different sizes of ground rock in its composition. There are, essentially, three different sizes of ground rock particles—sand has the largest particles, silt particles are smaller, and clay has the smallest particles. The size of the particles determines how porous the soil is; that is, how quickly water and nutrients move through it. Porosity is important also for gas exchange—roots need oxygen from the air. Sand with its large particles is the most porous and clay with its very small particles is the least porous. Water moves very quickly through sand and moves through clay very slowly. Natural soils are classified by the mix of the different particle sizes and the organic humus. You can read descriptions of the twelve major textural classes of soils as defined by the United States Department of Agriculture (USDA).

Different parts of the country have different types of soil. In Austin, Texas, where Mr. Smarty Plants lives, the soils have a high clay content and, thus, are not very porous. We have native plants here that are well-adapted to our clay soil; but, if we want to grow something that isn't native to our area, we usually have to loosen up our soil by adding sand and/or humus to it. You can read about your Nebraska State Soil which is more porous than ours here in Texas. Your soil will grow plants that our Texas soil won't grow. The bottom line is that different soils will support different plants.

Although texture is the major way to classify soils, there are other components of the soil that are important, too. The acidity or alkalinity (the pH) of the soil is important and also the nutrients (for example, potassium (K), nitrogen (N), and phosphorus (P) which are the most important).

Interestingly, however, most commercial potting soils don't contain "soil" at all. They are made up of peat moss, finely shredded barks, compost, and perlite (puffy volcanic glass to increase porosity). Potting soils, or store-bought soil, is made to support house plants although there are different mixes for different types of plants. The ideal potting soil is porous enough so that water is able to flow through it and deliver nutrients but not so quickly that the water is immediately lost. There are different mixes for flowering plants, orchids, and cactuses, to mention a few. For instance, potting mix for orchids is composed almost completely of bark. You can read how to make your own potting soil mixes,

Since I believe, from your e-mail address, that you are an elementary school student, you can find more information about soils geared to kids from University of Illinois Extension Service.

 

 

 

More Soils Questions

Garden instructions from Austin
June 12, 2013 - I'm a beginning gardener putting in some new landscaping in my front yard in north central Austin, TX. The yard faces almost due east, so it gets full sun until early afternoon, when the house's sha...
view the full question and answer

Leaf drop from maple tree in Minnesota
August 15, 2008 - I have about a 30 ft maple tree in my yard, last fall I trimmed it pretty good because the branches were getting low where you could not walk under it or get grass to grow. This is the 2nd time in abo...
view the full question and answer

Native Plants for Shaded North Slope in Ohio
January 03, 2013 - I have a shaded north hillside which needs erosion control plants. Mostly moss and very thin grass grows there now. Please help!
view the full question and answer

Turf grass for a sandy site in central Texas
February 16, 2015 - I want to plant grass over an old sand volleyball court in our back yard in Bastrop, Texas. What is the best way to go? Adding top soil and buffalo grass seed or try St. Augustine?
view the full question and answer

Plants to replace hydrangeas in a wet area in New York
July 09, 2010 - Dear Smarty, Two years ago I planted 4 Endless Summer Hydrangas in front of the front porch of my summer cottage on Saratoga Lake. The first year they struggled the second they are limp. Can you give...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center