Purchasing a soil mix

A container garden is a good case for store-bought soil mix, which is not heavy and dense: It contains and holds nutrients your plants can use, and it drains well. Potting soil can contain all or part of the following ingredients:

1 Organic matter: The organic matter in potting mix is typically some or all of the following: dried manure, compost, peat moss, and finely ground bark. It adds nutrients to the soil.

1 Perlite: Perlite appears as little crunchy white "pebbles" (they're actually smaller than most pebbles); interestingly, perlite is a natural volcanic ash that's been superheated and fluffed up, like popcorn. This substance increases the flow of air while helping the soil hold water.

1 Vermiculite: This mineral has been heated and fluffed up, though its form is flat and flaky. It increases airflow, retains moisture, and helps make minerals accessible.

1 Coarse or "sharp" sand: The sand in soil mixes is not beach sand, which is too salty, or river sand, which is too fine. Coarse sand helps with drainage.

1 Moisture-retaining gels: When they come into contact with water, these gels swell up and then slowly release it back into the mix over time.

1 Fertilizer beads: These fertilizer sources usually look like tiny yellow or brownish BB's.

1 A bit of charcoal: Manufacturers include charcoal mainly to absorb odors and gases from the natural decomposition process of the other ingredients.

To be honest, the majority of potted plants are perfectly happy with a general, all-purpose potting soil mix. You may want to buy a more specialized one if you're growing something with special needs — for instance, potted azaleas like a mix that's more acidic, and cacti, of course, like one that has a higher sand content.


Of course, if you're aware of a certain plant's special requirements, nothing's wrong with buying regular, general potting soil and then mixing in whatever else the plant needs — sand, lime, moisture retaining gels (see the next section), whatever.

You may see sterile potting mix touted on the bags and bins. All the term means is that the mix has been treated to kill possible pests, diseases, and weed seeds. That's a good thing!

You get what you pay for. Cheap potting soils seem to have too much peat moss or poorly shredded bark, or they lack perlite or vermiculite. You can't always rip open a bag in the store and shove your hand it to check it out (though some places have a display of samples to help you choose). So read the bag with care — not the claims about how terrific the contents are but rather the list of ingredients and their various percentages.

Whipping up your own soil mix

Yes, you can create your own soil mix, but it's not really a matter of saving money, because you have to purchase individual ingredients separately and then mix them. It's certainly not a matter of saving time, either. What it is, my friend, is a matter of control. When you make your own mix, you can make sure every bit of it is of good and consistent quality. Best of all, you can customize. If the store-bought mix seems too heavy, you can easily lighten it by stirring in some more perlite or some finely ground bark. And of course, you can make a blend that's more acidic or more alkaline as need be. The most commonly available bark is composted, hardwood, fir, or pine bark — all are fine to use.

Here, then, are some recipes to follow when stirring up a batch of your own mix:

1 A standard mix (also sometimes called houseplant thirds because it's so suitable for the majority of common houseplants): One part packaged soil, one part peat moss, and one part perlite or sand.

1 A light mix, for plants that like good drainage: Two parts peat moss, one part sand, one part perlite, and maybe a dash of powdered lime (the mineral, of course).

1 A heavy mix, for plants that like their soil more moisture-retentive:

One part peat moss, two parts bark, one part sand, and maybe a dash of powdered lime.

i Tree and shrub mix: One part sterilized topsoil, one part peat moss, two parts bark, one part sand, and maybe a dash of powdered lime.

Moisture-retaining soil polymer gels are a good idea if your pots dry out really fast or you're going on vacation or if you're simply not the sort of person to water diligently. These gels naturally absorb moisture when you water the plant, swell up with it, and then gradually release it to the roots for them to use between waterings. They come in crystal form and should be mixed into the soil prior to planting. Follow package instructions; even a little too much makes your soil mix's texture a bit slimy, but that ewww factor may be a small price to for the convenience.

To properly plant a container:

  1. Dig a hole about twice as wide and a little deeper than the pot you are taking the plant from to put into the container. Mix ample amounts organic material with the soil you remove from the hole.
  2. Knock the plant out of the pot by holding the pot upside-down and tapping its rim on a hard surface, or thumping the bottom of the pot with your fist.
  3. If the roots look like they've wound around the bottom sides of the pot, pry them loose with your fingers or cut through them shallowly (vertically) with a sharp knife.
  4. Put enough soil in the bottom of the hole to bring the crown of the plant (the spot where the roots join the stem, or, if you can't see the roots, the top of the root ball) about even with the surrounding soil surface.
  5. Fill the soil in and around the root ball, making sure you press it in firmly, to eliminate any air pockets.
  6. Water the plant deeply with a slow stream of water. If the soil around the root ball settles, fill in the depression with more soil.
  7. Cover the soil with a layer of mulch (shredded bark, compost, wood chips, for example). This will keep the soil moist and cool, allowing the plant to become established.

Many gardeners use pebbles in their containers, which aren't really necessary, especially with today's well-draining potting materials.

Figure 16-2:

A cross-section of a container, ready for planting.

Figure 16-2:

A cross-section of a container, ready for planting.

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  • Gimja
    What holds more water soil or sand?
    8 years ago
  • INES
    Can you have too much peat moss in a soil mix?
    8 years ago

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