You can make a planting mix from scratch that your plants will love. It is easy and simple to do, takes little time, and is relatively inexpensive. The end result is worth the small effort and minimal cost.
First, begin with a good bagged soil of some sort. It need not be the expensive name brands for which you pay a premium. Just a reasonable quality soil as a base for the rest of the mix. For our project let's say you buy a 20 quart bag of this product - a common size in most nurseries.
Next, buy a small bag of pure worm castings. You will need 4 quarts - about 10 lbs - for this mix. Worm Gold is an excellent product - good quality and not unusually expensive. Nature's Big Bud Worm Castings makes a liquid version. Worm castings (worm manure) are nature's miracle fertilizer and soil enhancer. They are organic, all natural, and contain more than 60 beneficial elements your plants need and use in growing healthy, robust root systems, strong stems and branches and beautiful flowers or fruits. Once moistened, they retain water in your soil thereby providing an additional benefit of saving watering time and money.
Buy a small bag of composted steer manure. This is inexpensive and will add nitrogen to the soil in abundance. The key is to not use too much of this in your mix. I am suggesting only 4 quarts.
Finally, you will need one pound of natural powdered Shidigera yucca (Mohave Yucca) to add to the mix. Yucca is another organic, all natural product; it is a wetting agent (surfactant) and makes water wetter. This will allow water to also be retained in the soil and will give your plants a quicker way to absorb nutrients from the soil mix. Yucca also contains natural steroids such as saponin which will assist in insect and disease control once your plants absorb it into their system.
You now have the ingredients for success in making a nutrient rich, water retaining bedding plant soil mix. Putting them together is the next step. Dump the 20 quart bag of soil onto a flat clean dry surface. To it add 4 quarts of the worm castings and the 4 quarts of composted steer manure. Next add the yucca extract powder. With a shovel, turn the pile a few times until all the ingredients are well mixed.
This is your planting mix. Dig holes in your garden, fill them with this mix and plant your bedding plants or seeds in it. (This mixture is also ideal for container gardening - nothing better on the market at half the price you pay for prestige brand name products.) You will be more than happy with the results. So will your plants.