Is the soil I use too "heavy" for potted plants?

Question

I've read a lot about growing vegetables and herbs in pots, and most of what I read seems to suggest mixing my own "soilless" mix. What does that mean?

I use master nursery gardener's gold organic potting soil - is that any good? I am planning to plant tomatoes, lettuce, cucumbers, carrots, mint, basil, chives, rosemary, sage, and oregano.

Here's what I'd like to know:

Is the Gardener's Gold good enough for my purposes? Why or why not?
What does it mean that a soil is too "heavy"?
What does "soilless" mean?
Should I make my own mix?

Thanks so much

Answer 1

Your potting mix is probably like the all purpose mix below. Although many mixes also use coir or worm castings. It will be very good for growing your vegetables along with a good fertilizer. I like Whitney Farm.

Mineral soil or dirt is roughly equal parts clay, sand, & silt. Good soil, top soil, consists of 93% mineral and 7% bioorganic substances.

Soilless mixes have the advantages of being light, easy for roots to penetrate and free of insects and disease.

Potting mixes that contain mineral soil provide larger plants more stability because they are heavier. For larger plants, a potting medium containing soil is best. However, homemade mixes that contain soils have several disadvantages. Finding good quality topsoil is often difficult. Garden soil will contain pathogens and insects. Before using garden soil, it should be pasteurized. A growing mix that contains soil has a tighter structure and less pore space for root growth. This is sometimes called heavy. It must be amended with equal volumes of organic matter, sand and vermiculite or perlite.

All-Purpose Potting Mix
Use this nutrient-rich blend when planting or replacing plants in containers.
8 parts potting soil with vermiculite or perlite
1 part coarse sand
4 parts sphagnum peat moss, compost, and/or rotted manure



Lightweight, Enriched Potting Mix
8 parts potting soil
1 part perlite
1 part vermiculite
8 parts sphagnum peat moss
1/4 part greensand
1/4 part gypsum



Soilless Potting Mix
8 parts sphagnum peat moss
1 part perlite or sand
1 part vermiculite

Vermiculite has high water permeability and retention while perlite has high water permeability and low water retention.


A high proportion of clay particles will create heavy soil that is difficult for air and water to pass through, it is dense not friable. Perlite or very coarse sand is used to amend a heavy soil.
The opposite of "heavy soil," the imprecise term "light soil" refers to soil composed of relatively large particles loosely packed together. The term is often synonymous with "sandy soil."

Good Luck with the garden

Answer 2

I keep it simple and use Miracle Grow, it's great, no problems. Heavy soil is to compact.