Soil Basics (Get Excited!)

Soil gardening is one of my favorite methods for producing flavors, aromatics, essential oils, terpenes or resins from fruiting, flowering or blooming plants or trees. Growing in a healthy organic soil mix helps eliminate some of the hassles or problems that finicky or oversensitive plant varietals might run into in certain hydroculture systems.

A quality organic potting soil provides ease of adaptation to plant-specific needs in terms of nutritional uptake, beneficial microbial colonization, moisture retention and available oxygen for the root system, with little room left for error. These important factors can be controlled and influenced according to individual style—and every gardener will re-invent the wheel, so to speak, in order to come up with a system that works to his or her satisfaction.

The first step I focus on is developing a mix that is just right for me. Everyone has different opinions about what the ideal soil mix is comprised of—for example, is a soil that holds more water or less water more effective and what are the pros and cons of each formulation? My personal preference is a denser soil mix that holds more water weight and tends to take longer to dry up.

Coco and forest humus—I prefer Alaskan—possess exceptional water-retention properties and provide an ideal refuge for beneficial microbes. Along with a high-quality peat, these are the three primary ingredients that comprise the base foundation for what, in my opinion, is the ideal soil mix. White sphagnum peat moss has decent capillary action and tends to hold less water than coconut coir, but increases the cation exchange capacity of nutrients.

Currently, I favor an equal 50/50 ratio of Alaskan humus to high-quality coconut coir—the darker the better. Once this is thoroughly and evenly mixed, I take two parts of it and cut in one part peat and perlite at a 60/40 ratio. Perlite increases drainage properties and aeration in any soil or soilless mix.

A chunkier grade is preferred nowadays, it seems—compared to the traditional BB-sized stuff that used to be found in many cheap potting mixes. Finally, 10 per cent high-quality worm castings should be added to the total volume of the mix. Castings are a readily available source of plant nutrients that will stimulate growth and enrich the overall body of your soil mix.

Soil amendments are available by the boatload and more appear on the market every day. Worm castings, bat and seabird guanos, kelp or seaweed meals, oyster shell, azomite, crab meal, poultry litter, pyrophyllite clay, bone and fishbone meals—these are just a few of the many popular natural and organic amendments that will enrich the soil and provide complete nutrition in a time-released formula that is fully customizable to the grower’s preference. The more dry amendments that are available in the soil mix, the fewer liquid concentrated nutrients you’ll need to add, so long as the necessary elements are available to the plant.

However, before you go and dump boxes of additives into your fresh new soil base, research what they will do for your crop and in what increments. I use two separate mixes—one designed to stimulate lush, green, leafy structural growth in plants that are in a vegetative stage and the other containing higher amounts of phosphorous and potassium, designed to encourage healthy fruit set and flowering development in blooming crops.

Transplanting from the vegetative mix into the flowering one allows the crop an easier transition from one stage of growth into the next with less overall stress and provides the required nutrients in satisfactory ratios. Used in combination with certain liquid supplements or compost teas, peak growth potential is achievable at all stages with most plant varieties with these two formulations.

Once your ‘super soil mix’ is complete you can either let it sit so it can compost or pot it up and use it right away. Obviously space is a factor if a composting stage is in your plans, as the soil mix will need a place to sit for somewhere between 45 to 90 days.

Composting will break down many of the dry fertilizer elements into plant-available forms ready for absorption, but if this stage is skipped it isn’t the end of the world—the addition of enzymes and microbial inoculants will help make the non-available nutrient elements in the soil mix available to your plants.

You may also reuse old soil if you wish, from the previous harvest. This can be labor-intensive but it also helps reduce overall waste from the garden. I would avoid reusing soils that were exposed to root rot, mildews or root parasites for obvious reasons. Also, a good soil mix should maintain a spongy consistency throughout its growth cycle—a healthy rhizosphere and soil mix when fed properly will have immense amounts of fungal activity, causing the soil to stay spongy and absorbent.

Before potting up any containers, try lining the bottom of your containers with LECA (light expanded clay aggregate) or diatomite to cover up the drainage holes and prevent soil from falling out. This will enhance oxygen supply to the roots and the drainage properties of the soil mix and increase feeder root production. Lately, air-pruning containers, both fabric and injection molded, are my primary choice for both soil and soilless gardening—both root growth response and uptake of water seem to benefit from the air-pruning technology the containers impose.

You’ll also eliminate the hassle of root circling and becoming root bound too quickly by implementing these types of containers in the grow room. Wick systems are also advantageous as they require less watering maintenance. I definitely favor the kind of root development that wick systems create due to the constant capillary action in the root system—these roots are ductile but thick and usually fill up any available space in and around the growing medium.

I assume that because the capillary action initiates the uptake of the proper amount of oxygen and water, the plant is able to produce the exact root system it needs for constant feeding and ideal elemental absorption.

Watering your soil is a topic that everyone seems to have different opinions about. How much water should go into each container? How often should I water? Should I fertilize with every watering?

This is an issue that is often made to seem more complex than it really is—you should water the soil based on the types of plants being grown. For example, fast-growing annuals that develop vigorous root and shoot growth in order to produce a fruit, flower or seed at the end of their cycle might consume larger volumes of water than cacti, succulents or plants like orchids that absorb water and nutrients through foliage and aerial roots. Water uptake and consumption will also depend on the size of the plant and pot, as well as on temperature and humidity.

A simple rule of thumb is to ensure that the temperature remains around 75°F when the lights are on and that there is anywhere from 30 to 50 per cent relative humidity in the garden. This type of atmosphere will promote healthy water uptake by the plants along with a dense and vigorous root system so long as harmful pathogens are not introduced. Water every plant only when it needs it, judging by weight.

This can be tedious work for larger gardens, but it will ensure that every plant gets touched at least one time in the grow room. I feel a plant is ready for water when I can pick it up easily, despite its overall mass. A gallon of water weighs roughly eight pounds without any elements added into it, so once fertilizer is added to the mixture and given to the plant there is a noticeable weight gain.

I feel that providing water to the plant approximately six to 12 hours before it can show any signs of wilt is ideal, if possible. If you’re using liquid fertilizers or supplements, I recommend consistent usage as opposed to alternating feedings with water—use lower nutrient concentrations more often and it should provide the intended results.

These guidelines are my recommended ‘basic building blocks’ any time I am gardening in soil. You’ll likely want to change a few things in your garden, but that’s okay—this guide is intended to be for reference only, not a set of immutable rules that will apply in the same manner to every soil-based garden. Every grower faces a different situation and every garden reflects the grower’s individual style.