The soil in which your plant will grow will determine what you get out of the crop and what you will have to put into it. It will dictate watering, ideal type of irrigation, soil diseases, pests, how much fertilizer is needed, and even the taste. Yes, the ground influences the taste of the fruit! Ever wonder why Vidalia onions are so sweet? It’s the low sulfur soils that are common around the town of Vidalia Georgia.
The optimum soil for growing a tomato is good dark coarse slightly sandy soil with good organic matter content. The sandiness allows for good drainage and for a fresh exchange of water for the roots, allowing the roots to grow quickly without the soil compaction problems of clays, but good irrigation practices must be in place to lessen fertilizer leeching. In short, certain elements in fertilizers move with water. If you water a sandy soil from above the root zone and use dry fertilizer you run the risk of flushing the nutrients out of the root zone. This is called leeching (this will be further discussed in the chapter on fertilizers).
We could go into some pretty deep and scientific classifications of soil types and soil orders, but I figure if you want to get that technical about it you can read a college textbook on soils and still only boil it down to 3 or 5 mixtures of soil types that are common.
Let’s go over some common types of soils found in the backyards across America or in bags of commercial topsoil. Each one of the following types are classified in order of particle size which is a very important factor in how you grow your plants.
Clay soils (smallest particle size): usually red or rusty in color (stick together when moist)) these soils we are good soils to grow in but they come with their pros and cons:
- Good nutrient retention. Thus, making it a good growing soil with minimal fertilizer addition.
- Good water retention.
- Minimal fertilizer leeching
- Easily compacted forming a hard surface strangling the root system. (This can be overcome by aeration or tilling the soil and minimizing surface traffic.)
- Poor drainage so it takes longer to dry out and can cause water congestion or overwatering of the plant. This can increase the incidences of soil borne diseases
- When it does dry out It can be hard to get wet again quickly.
Sandy Soils: (the largest particle size) usually a lite grey to white color. When dry you can rub between your fingers and your skin remains clean. It has a few pros but mainly it is an undesirable soil type unless mixed with organic matter or other soil types
- If moisture is kept optimum roots grow quickly and unimpeded like clay.
- Fertilizer applied to root zone is quickly absorbed.
- Less soil born disease.
- Little moisture retention so constant moisture monitoring is necessary.
- Soluble elements such as Nitrogen and potassium easily leach away if strict watering practices are not followed.
- Little natural nutrient value.
Peat rich / Organic soils: Particle sizes can very, usually dark grey to black thick soil. Cakes together and holds shape in fingers. Can leave a stain on skin. Mostly composed of decaying plant material (peat) and can be quite acidic.
- High nutrient value.
- Good moisture retention
- Little to no leaching of nutrients
- Little water movement.
- Easily compacted
- Can harbor disease and cause grey wall (a non-pathogenic fruit disorder that will be discussed later in this blog)
The best soil mixture for growing tomatoes in a container
Growing tomatoes in a container or even growing tomatoes in a raised bed garden are great ways to produce the best crops for several reasons. One of the biggest reasons is you can mix your own soil or buy premixed soils so that your plant will have a better chance of success. Especially if your yard does not have the best soil for growing vegetables.
For containers it is quite easy and affordable. I like to buy garden soil and potting soil from the local home improvement store and mix them in a 70% garden soil to a 30% potting mix ratio. If you did not want to mix the two either one by itself would be suitable for most novice home growers. Potting mix tends to have much more peat moss in it and holds moisture well, while garden soil can drain quite quickly depending on the manufacturer of the soil. There are also some garden soils that have added fertilizer. This is an advantage because you will not need to fertilize as much when you first plat your seedlings or seeds.
For raised beds I like to use 60% topsoil, 20% peat moss, and the rest compost and earthworm castings if you can afford them. Topsoil and peat moss for a big, raised bed garden can get quite expensive so try to find a local landscape supply company and buy in bulk if possible.
The great thing about container gardening and raised bed gardening is that you typically do not have to worry as much about soil fungal diseases such as fusarium wilt, phytophthora, and root knot nematodes (microscopic worms that feed on the roots). Although the costs can add up, you have a better chance for success if you have a yard that isn’t suitable for growing vegetables like mine.
Go out there and get your hands dirty! Good luck and be sure to message me with questions or comments. Follow me on Facebook, Instagram or Twitter for more tips and tricks. I will do my best to answer any and all questions personally.