House plants are easy to grow when planted in the right soil. This is simpler than most people think. The vast number of various formulas for soil mixtures makes it seem complicated.
Yet probably no two blue-ribbon winners would be in total agreement as to the best recipe. What is the answer? Isn’t it the sterility, friability, and degree of acidity of the soil in use?
Market Demand For Packed Potting Soil
Why is there such a large market for packaged general potting and African violet soils? Apartment dwellers are not the only purchasers.
Isn’t it because the great public knows that it is less work to buy sterile soil than to use garden soil, alive with harmful (as well as wholesome, of course) bacteria, destructive pests, and bothersome weeds?
These have to be removed through pasteurization. A thrifty indoor gardener, however, can do this by using either heat or chemicals.
Heat pasteurization is for homeowners only. The resulting by-product, a potent odor, is ample grounds for the landlord to break a lease!
Remember that the desirable bacteria needed for transforming insoluble into soluble nutrients are also destroyed by heat.
Benefits and Methods of Soil Pasteurization
For those whose philosophy is to try anything once, to sterilize soil by heat, either steam it in a pressure cooker at ten pounds for 30 minutes or bake it (moistened first) in the oven at 180 degrees for two hours. Wait at least three days before using.
Chemical Sterilization Methods
Of the several ways of sterilizing soil chemically, only the capsule method is easy enough to be feasible for amateurs.
Two capsules containing ethylene dibromide, available at garden centers under trade names, will pasteurize a bushel of moist soil.
The temperature of the soil needs to be at least 50 degrees. A ten-day period is necessary for complete penetration of the vapor through the soil.
Clean Containers Make Indoor Gardening More Fun
Sterile flower pots are equally important. If your time is valuable to you, do as the commercial grower does: buy new ones.
If you prefer to be economical, thoroughly scrub old pots using a bleaching agent and then scald them with boiling water.
Have you seen an experienced gardener testing soil for its porosity and lightness by clenching a small amount in his fist?
If, instead of remaining crumbly, the soil tends to mat, it needs peat and perlite added to it.
Importance of Friable Soil
Friable soil is necessary for two reasons: First, for the unhampered expansion and penetration of growing delicate roots. Even porous soil may be compacted by improper potting techniques.
To prevent compaction, use dry soil for planting; tap the pot on the bench to settle the soil in the same manner as the cake batter is tapped before the pan is placed in the oven; water after planting to allow the water to complete the tamping action.
The second reason for friable soil is to provide rapid drainage. Water passes quickly through friable soil.
Even good drainage doesn’t eliminate the hazard of overwatering. Check the technique of watering and the size of the pots.
Watering from the top necessitates looking at your plant within an hour to ensure it is not sitting in water.
Always keep in mind that water-logged roots can no longer obtain oxygen. They die. Oversized pots provide plants with more soil than is needed. This means it takes longer to dry out. Feel the soil before watering.
Incorrect Soil pH
Do the leaves of a favorite house plant start to yellow around the edges? Perhaps the soil is too alkaline, with a pH factor of over 7.3; thus, manganese and iron are unavailable for the plant’s use.
The degree of acidity or alkalinity of soil is known by its pH factor, 7.0, being neutral. When the pH factor is incorrect, certain elements will be unobtainable. Similarly, over 8.0, potash can not be used by the plant.
At too low a pH, under 5.0, phosphorus is no longer soluble. Most house plants prefer mildly acid soil, with a pH factor ranging from 6.0 to slightly under 7.0.
A few plants, such as gardenias and poinsettias, thrive in the soil as acidic as 5.0 to 5.5.
How To Determine Soil pH
There are two ways of determining the pH of the soil to be used for transplanting houseplants. Whether packaged or garden soil is to be used is immaterial. Test it!
(1) Do it yourself by purchasing a soil-testing kit. Directions, easy to follow, are enclosed.
(2) Or take advantage of your state’s agricultural extension services.
Many experiment stations provide soil tests free of charge. Others ask for a small fee. Usually, about two cups of soil are submitted; your state department will give particulars.
In addition to being informed of the pH factor, you will learn the degree and adequacy of plant nutrients in your soil.
Testing and Adjusting pH Levels
Make tests periodically to keep track of the effects of fertilization. Correct feeding will maintain the right pH level for the plants being grown.
Organic fertilization requires a pH factor of between 6.0 and 6.9. At this pH, the bacteria in the soil can break down the nitrogen into a soluble form.
Organic fertilization results in a gradual lowering of the pH. The pH may be raised by the addition of ground limestone at the rate of one-half ounce per peck of soil (4 1/2 six-inch pots equal a peck).
Should the pH need to be lowered to make more acid, add aluminum or iron sulfate at the rate of one-half ounce to 7 1/2 six-inch pots of soil. Within a month, retest the soil for the accuracy of the pH adjustment.
Soil pH Variation and Testing
It is a good practice to make tests at the end of summer on the soil of houseplants that have been outdoors.
Usually, the pH factor will be a good deal lower because heavy thunderstorms have washed out much of the lime content.
Soil Recipes For Potting
Once the sterility, friability, and degree of acidity are correct, then it is time to think of soil variations.
Most recipes for soil are in terms of bushels, which are impractical for the average homemaker growing only a few plants. Thus, the recipes given herewith are for potting four plants in 3 1/2-inch pots.
(A little smaller pot is used for measuring than is to be used for potting. Multiply this times the number of pots to be transplanted. This can be doubled or tripled to meet specific needs— simpler than trying to break down tremendous portions.)
Notice the use of German peat moss throughout. This is the coarsest peat and provides splendid aeration and sponginess.
If you can’t get it, use plain sphagnum peat. Perlite, a sterile, lightweight substitute for sand, is recommended.
Scientific Indoor Gardener
Why not become a scientific indoor gardener? Buy sterile soil and alter it with peat moss and perlite. Then, have it tested to eliminate guesswork. The reward? Lush, handsome houseplants!
44659 by Bill And Olive Hull