It may surprise you to learn you can make your own potting mix for growing tomatoes for less money than the cost of buying a commercial potting mix …
… and your homemade potting mix can be better for your tomato plants than what you buy at the home improvement store.
Plus, you can put together your potting mix any time of year even before planting season, while you’re waiting for spring to come.
Potting mix and seed starting mix have slightly different ingredients. That’s because they have different tasks.
The job of a seed starting mix is to give your tomato seeds a safe environment so they can sprout, develop their first couple of sets of leaves, and remain disease-free. The seed itself provides the initial food for the plant, so seed starting mix need little (if any) fertilizer to do its job.
Put simply, the best seed starting mix is sterile and has little fertilizer.
Potting mix for tomatoes, on the other hand, has a different function. It will become the permanent home to your tomato plants while they are in containers or pots. That means the mix needs to provide both a good home plus food.
The best potting mix for tomatoes may or may not be sterile, yet it must contain nutrients in order to grow healthy plants.
You save money
Commercial potting mixes are more expensive to buy than the ingredients you need to make your own potting mix.
You create a better growing environment
Many pre-packaged potting mix formulas have too much garden loam or peat moss. These ingredients compact in containers, producing a heavy, hard texture which makes aeration and drainage difficult. To compensate, mixes include chemical wetting agents, which are not really necessary if you have a balanced mixture in the first place. Some commercial mixes have other ingredients, too, like excess pine bark, which gives the mix a high-acid pH and consumes extra nitrogen. That deficiency must be replaced by fertilizer in order for your tomatoes to thrive.
(Check out these tips to use if you decide to buy commercial potting mix for growing your tomatoes.)
Potting mix needs to
A good potting mix is a blend of ingredients that fulfill those functions. A combination of both inorganic and organic ingredients to meet tomatoes’ needs for growing healthy leaves, blossoms, and fruit.
Inorganic Ingredients Drain and Aerate. Inorganic ingredients like sphagnum peat moss, peat coir, perlite, vermiculite, and coarse sand give the mix good drainage for water and allow pockets for air to move.
Organic Ingredients Retain and Nourish. Organic ingredients like compost, humus, garden loam, and commercial potting mix play two important roles. First, they offer water retention, helping the mix hold water rather than repel it in order to keep the plant hydrated and keep nutrients moving to the leaves. Further, these organic ingredients provide nutrients for your tomato plant to grow healthy and strong.
There are dozens of recipes to use to make your own potting mix. Here is an
easy one: 1 – 1 – 1. (We at Tomato Dirt use this recipe.)
Experiment with these specific ingredients to find a good combination that works for you.
It's your call.
If garden loam or garden compost are ingredients in your mix, you may wish to sterilize them in order to eradicate bacteria and fungus that have overwintered in the soil.
To sterilize, heat your oven to 180º - 210º F. Spread the ingredients in a shallow pan. Bake the soil for 45 minutes. Allow it to cool and then add it to your mixture.
More about Potting Mix and Seed Starting Mix