Proper soil worth the effort

July 26, 2007




For about 10 years or so I have grown houseplants, cacti and various cuttings, but couldn't seem to get it right. My plants either died or they were not too appealing. The one plant that didn't die on me was the cactus.


As a novice, I had no knowledge of the proper soil to use. When I would go shopping I'd look for an inexpensive bag of potting soil. I would say to myself, "After all, it's just for plants." I didn't know how wrong I was.




As a Victoria County master gardener since 2005, I have learned and realized that there is a lot more to a bag of soil - and surprised myself when I successfully propagated plants at home for the master gardeners last fall.


I've learned that, besides proper watering, success in propagating plants comes from a top-quality potting soil. Since then, I can say from experience what a good quality potting soil can do for your plants. So I will share with you what I have learned.




Most of us have grown a plant or two only to have the soil dry up as hard as brick. Plants need soil that will hold water, nutrients and oxygen so that their roots will produce lush, healthy stems, leaves and flowers.


The question is: How do we know what soil to buy?


The ingredients in the potting soil are the answer. It would be nice if retailers would have a sample of what's in the bag so you can see what you're buying. A few states are required to give detailed labels on all soil products, but in most states, gardeners are on their own.


A good potting soil should retain moisture and drain well. Squeeze the soil in your hand. You want a soil that holds together when compressed, but crumbles when tapped.


A good quality soil will contain some or all of the following ingredients, but the percentage may vary according to the purpose of the mix.


Sphagnum peat moss, sedge peat (least desirable) or aged forest products





Wetting agents and water-holding polymers (optional)

Lime for balancing the pH, if needed

Nutrients - added in the ratio for the desired plant and growth effect

What's available


When shopping for potting soil, you will find some brands more expensive than others. Keep in mind what you are going to use it for. Your choices include general purpose, premium, professional and special-purpose potting soil.


The general purpose is used as stated - for general use where no high demand in performance is desired. Many times this is the cheapest blend but it most likely has the least desirable characteristics, is coarse and has the least nutrients.


The premium mixes are a step up, containing a finer texture of high quality blends of peat, vermiculite and perlite plus some wetting agents.


The top choice is the professional and best blend of premium products, wetting agents, plus a complete nutrient package that includes micronutrients.


Lastly, there are specialty mixes. There is also potting soil sold for use in flowerbeds and gardens, but simply adding organic matter to these sites is best. For established trees or shrubs kept in containers, look for a heavier potting soil so they don't topple over.


I've seen torn bags that contained what looked like scrapings from the woods - dirt, bits of pine needles, pebbles and pieces of bark. Such a product is fine to use as an amendment in a flowerbed, but I would not recommend using this for your prized houseplant or container plant.


In a container you want to use a professional potting soil that will provide good drainage and air exchange, and that has the ability to hold water and nutrients for plants to grow. You might pay a little more, but you're getting a better value.




One of the drawbacks to soil-less professional mixes containing peat moss is they can be difficult to rewet if they get too dry. If allowed to dry out, the mix will practically shed water.


Some mixes contain water-retaining polymers and/or wetting agents to prevent this. Polymers help absorb excess moisture and release it back into the soil as needed. The wetting agents help absorb water evenly and easily throughout the soil. Mixes that have both are great for plants that dry quickly, such as hanging baskets and plants in window boxes.




You will find potting soil that has fertilizer or nutrients added, but the amount is rarely enough. It is recommended that you fertilize all your plants after potting. Some of the premium potting soils will have a slow-release fertilizer that may initially last for several months.




Some potting soils are formulated with particular plant groups in mind. I'd recommend using these as they have certain soil amendments added in higher levels for their unique rooting and plant characteristics. They include cacti and succulents, bonsai, orchids and African violets and seed-starting mixes. Shop carefully and compare the package contents to decide if the plant-specific mix is what you need.




Superstores with gardening departments will have a wide choice of brand names and offer smaller packages of potting soil. You will find in garden centers and nurseries that the choice in brands will narrow, but there will be a full line of soils, some of them in larger bags.




The most important thing to look for is the list of contents in the bag and a satisfaction guarantee. Your potted plant can only be as good as the soil in which it grows, and when a plant is limited to a container, the only soil it has is that which you give it.


The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas Cooperative Extension-Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, Texas 77901; or, or comment on this column at



July 26, 2007

There are various general purpose and specialty potting soils available in the market place for planting purposes. However, you can make your own soil mix for container gardening or sprouting seeds. If you Google "potting soil recipes," there are more than 175,000 Web sites that might provide you with what you want. But a proven recipe for starting seeds is as follows:



1 bushel vermiculite


1 bushel peat moss


(finely-ground pine bark can be substituted for peat moss)


10 tablespoons 0-20-0 super phosphate


1/2 cup 12-24-12 garden fertilizer


Dampen and mix material thoroughly