The real dirt on potting soil

Soil Content

Soil content is especially important in hanging baskets where a small amount of soil must provide a good foundation to the plant all summer..
Soil content is especially important in hanging baskets where a small amount of soil must provide a good foundation to the plant all summer.. | Source

Seed starting

coir or peat moss alone is a sufficient medium to start seedlings.
coir or peat moss alone is a sufficient medium to start seedlings. | Source

Soilless Soil?

Mix up potting soil or buy bagged?

Good quality potting soil is not really dirt at all, but a mix of several ingredients that may include peat moss, vermiculite, sand, perlite, core or compost.

Make your own potting mixes and seed starting mixes if you need a large amount. It may be easier to just buy a bagged mix if you need a small amount.

  • Seed starting mix is predominantly peat moss and can contain bark or coir (coconut fiber). Use this simple mix to start seeds.
  • Potting soil is a light, weed and disease free blend of ingredients suitable for potting and growing plants. Use this mix for container gardens.

Coir disk

Compressed into a disk, all the water removed, this disk of coir will expand to fill the quart container.
Compressed into a disk, all the water removed, this disk of coir will expand to fill the quart container. | Source

Rehydrated coir

From a disk less than an inch thick, this coir fills up the container when moistened.
From a disk less than an inch thick, this coir fills up the container when moistened. | Source

Organic and inorganic

Ingredients in potting mix are organic and inorganic.

Organic materials usually make up about 40% to half of the materials in potting soil. Inorganic ingredients compose the balance of the planting mix.

Canadian sphagnum peat moss is the most common variety of peat moss used by home gardeners. The words peat moss or peat refer to Canadian sphagnum peat moss in this article.

Peat moss is quick draining and also water retentive. It's lightweight and inexpensive. Peat is difficult to work with until it is moistened. Many gardeners are replacing all or part of their peat moss with coir.

You do not need to add fertilizer to seed starting mixes. Extra fertilizer may burn new, fragile seedlings. Add compost to your mix to provide nutrients that young plants require.

Inorganic materials improve drainage and add weight Inorganic ingredients like sand, vermiculite, and perlite generally lend porosity to a mix, but they can also help retain moisture and add weight or density.

I started making my own container mix after buying some bad, unidentifiable bagged material labeled as potting soil from a national chain.

Potting soil

Potting soil serves to anchor plants. The content of potting soil can be adjusted for top heavy plants and high wind conditions.
Potting soil serves to anchor plants. The content of potting soil can be adjusted for top heavy plants and high wind conditions. | Source

Seed starting and potting soil recipe


Basic Seed Starting Mix

8 parts peat moss or coir

1 parts perlite

1 part vermiculite


Basic Potting Soil Mix with Compost

6 parts Sphagnum Peat Moss or coir

1 part Perlite
1 part Vermiculite

2 parts Compost


Enriched Basic Potting Mix


6 parts Peat Moss or coir

1 part Perlite
1 part Vermiculite

2 parts Compost

1 part sharp sand or builder's sand

Green Sand (add green sand based on the size of your container)

Slow release (fertilizer add fertilizer based on the size of your container)

Free plant tags

Keep plastic utensils out of the landfill for one more year by turning them into plant markers.
Keep plastic utensils out of the landfill for one more year by turning them into plant markers. | Source

Garden tip

Buying bagged commercial potting soil, manure or compost, is easier to open if you have a cheap plastic knife handy. Open potting soil bags by dragging a plastic knife across the bag. It will open those weighty bags of potting soil or topsoil faster than most pricey garden gadgets.

Before dumping disposable plastic ware, use it one more time. Recycle plastic forks, spoons and knives as plant markers. You will probably use plastic flatware at a picnic this summer and most of it will go into the trash.

They aren’t frugal if you buy them especially for this purpose , but if you happen to use plastic ware this summer, recycling for garden use will keep just one more thing out of the landfill.

Bagged Amendments

Slit open bagged soil with a plastic picnic knife. Keep this cheap bag opener in your garden tools box.
Slit open bagged soil with a plastic picnic knife. Keep this cheap bag opener in your garden tools box. | Source

Peat moss vs coir

Canadian sphagnum peat moss is a natural, organic soil conditioner.Peat is partially decomposed sphagnum moss. It absorbs and holds 16 to 20 times its dry weight in water. Peat moss is excellent for seed starting because it cannot sustain the soil-borne fungi that cause damping off.

Plants that require acidic soil, like azaleas, conifers or rhododendrons, will benefit from the addition of slightly acid peat moss. Most plants thrive between 6.0 and 6.5 because the most nutrients are available in that range.

A pH between 6.6 and 7.3 is neutral. Higher numbers are alkaline. Lower pH numbers are acidic. Most garden vegetables grow best in neutral to slightly acidic soil. Peat moss has a pH of 3.6 to 4.5, which is considered acidic.

Coir is an organic medium that can be used as a peat substitute. It is a natural fiber from the husk of a coconut. Coir retains more water than peat. The coconut fiber absorbs about 30% more water than peat moss. The pH of coir (5.5 to 6.8) is more neutral than that of peat (3.6 to 4.5).

Because coir has a more neutral pH and greater water holding capacity, it is an excellent choice for hanging baskets.

It is easy to transport or store in it's compressed form. When soaking, make sure the container is big enough for the expanded coir. Remember, coir will expand five to seven times.

Try coir (coconut fiber) instead of Canadian sphagnum peat moss in these applications:

  • Compost - A carbon rich (brown) material that balances nitrogen-rich (green) kitchen scraps or grass cuttings in the compost piles.
  • Soil amendment - Use coir to amend clay soil making it lighter, more porous and able to hold water. In sandy soils, it creates water holding capacity.
  • Potting soil - Coir as an affordable main ingredient when making your own potting mix.
  • Bedding material – Vermicomposters use coir as bedding for worms.

Conserve potting soil

Place small empty pots  upside down in larger pots to conserve potting soil.
Place small empty pots upside down in larger pots to conserve potting soil. | Source

Custom container mix

Make your own custom container mix with these key ingredients.

Sphagnum Peat Moss - The most frequently used ingredient, peat moss decomposes slowly and holds water.

Coir - Coir is a coconut fiber with excellent water holding capacity.

Soil - soil is seldom used in seed starting or potting mixes. If you do choose to use topsoil or garden soil, be sure to sterilize it first. Spread it out on a cookie sheet and bake it for 20 minutes at 200° F. Stir soil halfway through the process. Some organic mixes still use real soil in their bagged mixes.

Sand - Sand such as builder’s sand, or coarse sand, will add air space to potting mix.

Avoid fine sands that will create a dense, heavy mix. Sand is a good choice for big, top-heavy plants that may tip over.

Perlite - Perlite is a pH-neutral, lightweight volcanic rock. It can be used to replace sand.

Vermiculite - Vermiculite is light and should be handled gently. Otherwise it compacts and loses its air-holding ability.

Compost - Compost holds water well and provides nutrients. What type of nutrients and how much depends on the materials used to make the compost.

Composting

Rodale demonstrates composting on a large scale at the Emmaus, Pennsylvania farm. Composting is free black gold for your garden.
Rodale demonstrates composting on a large scale at the Emmaus, Pennsylvania farm. Composting is free black gold for your garden. | Source

© 2014 Patsy Bell Hobson

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15 comments

Patsybell profile image

Patsybell 23 months ago from zone 6a, SEMO Author

gardener den Thank you for reading my hubs. Good luck with your gardening. I would love to hear how it worked for you, or what modifications you make.


gardener den profile image

gardener den 23 months ago from Southwestern, Pennsylvania

Patsy

Great Hub on how to mix your own potting soil. Continue the great work in writing! And I am going to try to make some of your potting soil mixes. Great Job! Gardener Den


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

PegCole17, It's very helpful to get feedback like this. Thank you. I appreciate your comments.


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

And, OldRoses, I love your succinct comments. Thank you for reading my Hubs. I appreciate you.


PegCole17 profile image

PegCole17 2 years ago from Dallas, Texas

Thanks for sharing these useful tips on potting soil. I really liked the one about using a smaller pot inside a larger one to conserve on the soil needed. This will be especially useful with the large container pots I've been using the last few years to grow plants on the porch. I have some really hearty blueberry bushes that produce enough fruit to take me through the year and they were grown in peat moss.

I also liked the idea of recycling of plastic utensils for plant markers.


OldRoses profile image

OldRoses 2 years ago from Franklin Park, NJ

Great hub! Your explanations are clear, simple and easy to follow. I love hubs that take the mystery out of gardening. Well done.


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

Thank you, rebeccamealey. I appreciate your comments. Petunias are easier to grow these days. This petunia is a trial plant from Proven Winners. Available this year at most independent garden centers and many of the big box stores.


Au fait profile image

Au fait 2 years ago from North Texas

Wish I did that everyday Patsy. You're article really is outstanding and it's already had some interest on my FB page.


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

Au fait, Thank you. Your kind words have made my day. I only wish more people could begin their day by reading such heartwarming comments. You have inspired me to pass on the nice comments to someone else. Look what you did. Started a wave of kindness!


rebeccamealey profile image

rebeccamealey 2 years ago from Northeastern Georgia, USA

Great info! Love the soil saving idea. Your petunias are lovely!


Au fait profile image

Au fait 2 years ago from North Texas

Wish I would have had your guide years ago. I tried to use potting soil for convenience for container plants and they all grew to stem if you know what I mean. Out of frustration I would go and get soil from a field on our property (we lived in the country) because at least the plants would be normal, but it was heavier too, and made it hard to manage the larger pots.

Anyway, I think this article is fantastic for helping people like me who have no trouble growing things in the ground, but when it comes to understanding all that commercial stuff, I'm lost.

Now I live in an apartment and don't grow anything. My plants are silk because I don't have enough time in the day to do all that needs doing now without adding living plants and their care to the equation.

Excellent article. Posting on FB, pinning to my 'Trees, Plants & Flowers' board, and will share with HP followers. Voted up and BAUI.


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

Thank you for your kind words, MsDora. I love sharing with other Gardeners . I always learn something too.


MsDora profile image

MsDora 2 years ago from The Caribbean

Great information, Patsy. You deserve your hug of the day. I learn so much about soil from one article. I'll be back for more. Thank you for sharing such valuable information.


Patsybell profile image

Patsybell 2 years ago from zone 6a, SEMO Author

Thank you Jackie, you made my day. I appreciate your kind words. I believe soil is the most important element in any garden. I can buy any kind of seed or plant, but it will not thrive if it cannot get what it needs from the soil.


Jackie Lynnley profile image

Jackie Lynnley 2 years ago from The Beautiful South

If you haven't thought about it Patsy you should write a book! You have so many great things here! I think you must know all there is to know about plants and flowers. You look like the green thumb of the plant world to me! ^

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    Patsy Bell Hobson (Patsybell)214 Followers
    113 Articles

    I inherited my love of gardening from mother and grandmother. I am a garden blogger, freelance writer, Master Gardener emeritus.



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