Arid-Southwestern Gardening Information
Gardening Tips by John Begeman
Navigation BarReturn to Gardening Home PageSearch the Gardening siteSee the Frequently Asked QuestionsGo to Gardening Site Map

[e-Mail me the Articles]    -     [Search the Articles]    
  • Articles Index : Flowers - Annuals



    2. How to Stimulate Root Growth of Garden & Landscape Plants - Top

    Plant roots are the foundation of plant growth, from the smallest flower to the largest tree. They hold plants in place and absorb the water and nutrients necessary for growth. If roots aren’t heathy and vigorous, the plant will be weak and may eventually die. But roots can be stimulated and encouraged to grow by following just a few simple steps.

    Regardless of the plant, at the time of planting, the outer edge of the root ball should be scratched, scuffed or in some fashion, roughened. The object is to loosen and pull some of the root tips out from their tight adhesion to the root ball. In so doing, these roots will immediately begin growing into the surrounding soil after planting hastening the plant’s establishment.

    For small plants like annual flowers and vegetables in 2 to 4 inch pots, this pulling of the roots is best done with a table fork. The root ball should not be pulled apart, but the edge of the ball and outer roots should be scratched enough to loosen the roots. For larger herbaceous garden plants or woody landscape plants in one gallon size and up, I prefer using a standard three-pronged garden fork to loosen the outer edges of the root ball.

    Don’t worry if in the process of loosening the root ball, some of the roots are torn off. This will happen, especially on the small, fine-rooted herbaceous plants. New roots will form where the old roots tore away. In fact, many roots will branch and form multiple roots to replace the ones lost. This root branching will increase plant vigor!

    For larger landscape trees and shrubs, in addition to scratching and pulling the finer roots, it will be necessary to cut larger circling roots when present. Any finger-sized roots circling the outer edge of the root ball should be cut off with a sharp knife or hand pruners. If not removed, these large circling roots will cause the plant to be stunted and poorly anchored.

    To encourage rooting of garden plants including flowers and vegetables, mix lots of organic matter into the bed at the time of planting. The organic matter can be bagged topsoil, potting soil, peat, bagged compost or manure. In addition, mix in a fertilizer high in phosphorous such as ammonium phosphate (16-20-0) or bonemeal (4-22-0) at the rate of 1 pound per 100 square feet of garden bed area. Mix the fertilizer into the top 12 inches of soil.

    Phosphorous is the only substance that can be mixed into the soil to directly stimulate root growth. Other products marketed to promote root growth, such as Vitamin B-1, work under controlled laboratory conditions but are not effective when used in gardens and landscapes.

    Although garden beds should be amended with organic matter, if your digging to plant individual plants (trees, shrubs, vines, etc.) do not add organic amendments. Both native and non-native landscape plants should be planted directly back into the soil removed from the planting hole. Creating a rich soil in the planting hole may sound like a good idea, but it’s not! Rather than encouraging roots to grow, a hole with organic amendments creates a ‘pot-in-the-ground’ from which roots have a very difficult time escaping. Just be sure to dig a hole 2 to 3 times wider than the root ball. This will loosen the soil and is the best way to encourage roots to expand out rapidly from the root ball.

    “Solar-Baking of Garden Soils to Eliminate Pest Problems” will be the topic for this week’s garden demonstrations. They will be presented on Wednesday at 9 a.m. at the University of Arizona - Pima County Extension Center, 4210 N. Campbell Ave (central); and at 1 p.m. at the Wilmot Library, 530 N. Wilmot Road (east), and on Friday at 1 p.m. at the Oro Valley Library, 1305 W. Naranja Drive (northwest).

    Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona,
    520-626-5161. - Updated: April 9, 2006

    [e-Mail me the Articles]    -     [Search the Articles]