Ask Mr. Smarty Plants

We think you may have problems other than grasses for your various areas. Did the people installing your septic system check for distance from your oaks? Oaks (and other woody plants, including shrubs) have much more roots underground than canopy above ground. Those roots loooove septic lines, and go straight for the moisture, where they promptly mess up your lines.

This article from InspectAPedia.com Guide to Planting Trees or Shrubs Over or Near Septic System Components has a lot of information on planting trees and shrubs over septic fields (don't) or distances from those fields to plant trees (you don't have that much space).

Beyond that information, about all we can tell you is what we have told others who wanted to know what they could plant over septic systems and let you go from there. These are all Mr. Smarty Plants answers to previous questions and some have more links for information. These involve different areas of the country and different plants but all are applicable to your question.

June 28, 2010 Planting over septic tank in California

September 2, 2009 Native flowers from Door County WI

January 25, 2009 Plants that will not clog lateral lines with roots from Bulverde, TX

April 10, 2008 Native plants for septic field from Austin, TX

From the above answers, we hope you have inhaled the information that, especially in a small space, woody plants are not a good idea. As you have surely picked up from our previous questions above, native grasses or small herbaceous blooming plants are the best cover for septic fields.

Since we can't possibly designate plants for actual spots in your garden, we are going to go to our Native Plant Database, select Arkansas in Combination Search, and search first for "herbs" (herbaceous blooming plants), under General Appearance. The first go-round, we will click on "sun" under Light Requirements, and  Search. The next time around, again on "herbs," we will select on "shade." Then, the process can be repeated for grasses native to Arkansas. No woody plants, you are in enough trouble in that department already.

We will pick out one example from each selection; follow the plant link to our page on that individual plant to learn the expected size, bloom color and time, water needs and so forth. You can then embark on making your own customized list to fit your needs. Please note that many of the grasses that will be listed are not what you would consider lawn grasses, only buffalograss can be mowed and that only needs it about twice a year.

Plants for sun:

Herbaceous blooming plant-Coreopsis lanceolata (Lanceleaf coreopsis)

Grass-Bouteloua dactyloides (Buffalograss)

Plants for shade:

Herb-Aquilegia canadensis (Eastern red columbine)

Grass-Chasmanthium latifolium (Inland sea oats)