By Wayne Handlos
Many geraniums/Pelargoniums can be grown outdoors in the garden. The scented types
of Pelargonium do particularly well in the Mediterranean climate areas of California. These
plants are tough and can be very long-lived. A little supplemental water in summer will
keep them happy. However, the newer cultivars of any of the commercially available plants
are not usually so tough and require some pampering. In the ground most will require a
steady supply of water. In many parts of the United States, rainfall will keep the soil reason
-able moist but in dry areas supplemental water is needed. If dense and clay-rich, the soil
might benefit from the addition of organic matter. Home-made compost can be worked into
the native soil. The organic matter holds water and nutrients and slowly releases these to
In these days of small plots of land around the home and/or apartment and condo-living,
plants are more conveniently grown in pots. Here is my recipe for a potting mix. (All
nurseries and garden centers sell potting mixes – usually in a variety of types with a variety
of prices. Most of these mixes have a minimal amount of nutrients in them so fertilizers of
some type must be added to keep your plants growing.) Mix the following ingredients
thoroughly in a wheel barrow.
Potting mix A – 1 cu.ft.
Potting mix B – 1 cu.ft.
Coir – 2 x 6 ½" pots full
Perlite – 2 x 6 ½" pots full
Azomite – ¾ cup
Milorganite – 1 cup
Osmocote (pelleted slow release fertilizer) – ½ cup
Cotton seed meal – 1 cup
Vermicompost – 1 cup
Commercial organic fertilizer with mycorrhizal components – 1 cup
The first four ingredients of this combination provides a porous well-drained potting mix with reason
-able water holding capacity. I use two different commercial potting mixes (usually the least expensive
ones I can find) because none of them is fully suitable so this evens out the differences between them.
SuperSoil is commonly found. Less common is a Red Star mix. In the west, decomposed "forest
products" form the base of the mix but in the eastern and Midwest of the United States, peat moss
probably forms the base material. The coir is coconut hull "stuff" and the Black Gold Just Coir brand
is of the right texture and resembles peat moss. Baled coir I have found does not "fluff up" to the extent
claimed and seems very fibrous to me. Perlite and vermiculite are frequently recommended as interchange
-able but they are very different products. Perlite provides the drainage properties required and holds
water as well. I have not found any use for vermiculite and as an expanded mica product it quickly
compacts to its original form is then useless as a soil lightener and water reservoir.
Nutrients are provided by the remaining components. Azomite is volcanic ash that was deposited in an
ancient seabed in Utah and it now mined as a soil additive to provide trace elements to soil or potting
mixes. Milorganite and Osmocote are slow release fertilizers which will not burn the roots of your plants.
Milorganite is Milwaukee sewage sludge and is used extensively on golf courses. Osmocote and similar
fertilizers are effective for a few months. The cottonseed meal is a slowly decomposing substance which
provides nutrients over the long term (a year or more).
The vermicompost and organic fertilizer plus mycorrhizal components provide many living organisms for
the dynamic interactions between the plant and the "soil". In human terms, think "probiotics". Soil is a living,
dynamic ecosystem and, when all parts are functioning well, will provide your plants with nutrients and water.
The probiotics may enhance the absorption of nutrients and water from the soil, release organic compounds
to protect your plants from various disease organisms and provides a degree of resistance to plant pests,
in particular whiteflies. The "probiotics" include various bacteria, ectomycorrhizae (which work outside the
roots) and endomycorrhizae (which penetrate the roots of the plants).
^ Endomycorrhizae ^ ^ Ectomycorrhizae ^
While I am not a fanatical organic gardener most of the ingredients above are natural products (Osmocote
excepted) and, I believe, are healthier for our environment and planet than artificially produced substances.
This mix recycles well in the vegetable or flower garden and remains loose and friable even after years in
a pot or planter.