SOIL 
Potting soil is the all important factor to the success of your growing 
plants. Everything else that you might do is to no avail if you don’t 
begin with a good properly balanced potting soil. 
Let us start with the pH of the soil. The symbol pH is used to des- 
ignate the potential hydrogen ion concentration in the soil, that is, the 
range of acidity and alkalinity. pH 7 is neutral on the scale. Below 
it is acid and above it is alkaline. Most all plants grow best on the 
slightly acid side of the pH table. St. Paulias are in the plant group 
that prefer and need a pH of 6 to 6.8 to maintain good growth. 
The three major nutrients in the soil are nitrogen, potash, and phos- 
phorus plus several of the minor elements including calcium, iron, 
boron, sulphur, and magnesium. All of the above elements can be added 
to the soil in forms of chemical compounds. Carbon, hydrogen and 
oxygen is derived from the air and water, with the aid of sunlight. The 
process of transforming sunlight, air, and water into plant food through 
the leaf structure is known as Photosynthesis. All the above elements 
and plant functions are active only when the soil is in a good physical 
condition. 
Phosphorus is a plant food that seems to be lacking most in all types 
of soils. For St. Paulias, it is one of the dominating factors to stim- 
ulate good root systems and maturity in the plant, thereby causing the 
plant to bloom abundantly. The pH should not be much higher than sta- 
ted in the previous paragraph, for at pH 7.3 the phosphorus locks up 
with the calcium and forms the insoluble compound calcium phosphate. 
On the other hand if the pH is too low, it again locks with the soil iron. 
Nitrogen and potash are not affected by the pH range too much as in the 
case of phosphorus, but they will not be utilized by the plant if the acid- 
ity range varies too much either way. 
A good soil mixture is prepared in the following way. Two parts good 
garden loam. Two parts of well rotted cow manure. One part peat 
humus. One part sand. This gives a soil mixture that is high in humus 
content, which is very important. 
After mixing the constituents, the next step is soil sterilization. Dif- 
ferent methods are used to accomplish this task. Several chemicals are 
now on the market, but steam sterilization and oven baking are the two 
best ways to do a complete job of eliminating fungus, weed seeds, in- 
sects, and nematodes or any other soil born pests. After sterilizing, 
the soil should stand without being used, for it has been shown that 
steaming releases the nitrates in the soil to a point where they become 
very toxic to plants and will injure the root systems. If the soil is used 
immediately, the micro-organisms that feed upon the humus and convert 
it to plant food are temporarily inactive, and some time must elapse till 
they are again useful in manufacturing plant food. Small portions of 
soil can be sterilized in your oven in the following way. Bury a small 
potato in the pan of soil. Heat the soil until the potato is done, and in 
most cases this will be time enough to do a good job of sterilizing. If 
the soil must be used immediately, leach the soil by drenching with 
water, thus removing the toxic salts produced by steaming. .Up to 
now there has been no mention of fertilizer being added to the soil. 
