There are three ways to grow indoors, each with its own positives and negatives. The choice is up to you.
Soil is what we all know about – good old dirt. Stick in a seed, water, and a plant grows. That is the story outdoors, but soil indoors is another matter. If you use soil, (which I am defining as a soil-like product containing some nutrients), you must make sure it is sterile. Bags of potting mix stored outside at a store are often filled with insect eggs just waiting to ruin your day. If it contains a slow-release fertilizer, like Osmocote, or a quick-shot nitrogen fix like Miracle Gro, this will conflict with your feeding program.
Soil temperature should around 70 degrees or so. Rootlets will bake off in consistently higher temperatures. In cold soil, the temperature will cause a slowdown in the uptake of water and nutrients, stifling growth.
Soil mixes should have good texture, crumbly and loose. Water retention and drainage should be a happy medium, and the nutrients contained, if any, should be gone in 2 – 4 weeks (a clone veg cycle).
Organic products contain enough organic nutrients to feed your plants through most of your veg cycle. Adding perlite, growstones, or coir cubes will lighten the soil, allowing for oxygen to reach the roots and excess moisture to drain.
A soilless, sterile, non-nutrient medium is a great way to control every nutrient aspect of your plants. Made of peat or coco coir (shredded coconut husks), Sunshine 4 and compressed blocks of coco coir provide a great growing medium that is porous, drains well, and provides no nutrients to interfere with your feeding program. Coco fiber grabs calcium, so be sure to add CalMag, MagiCal, or other such products. Adding just calcium without the magnesium will cause the calcium to be unavailable.
Adding perlite, even as much as 50%, will lighten your mix, but will require daily waterings. The lighter your mix, the happier your plants, but only if you do your part and water. Whatever you use, be very aware of the weight of your plants when properly watered. Make sure drainage is excellent. If your soil is very heavy, it is too wet and you run the risk of losing your plants to root rot and root suffocation. Lifting your plants to judge their weight should be part of your regular routine.
It is best to water when the pots weigh light. At different times in its life, a plant will use up more water. If you stick to an every other day type schedule, you will both underwater and overwater your plants more than once. Stress = poor results. It is about realizing that your schedule means nothing to your plants.
Adding beneficial fungus and bacteria will help your plants tremendously. Great White, Orca, Plant Success, and others are great sources for both soil and hydroponics. The bacteria are aerobic, which means it flourishes in the presence of oxygen. This adheres to your roots and actually helps block out anaerobic bacteria, such as pythium. (Anaerobic means existing in the absence of oxygen.) The bacteria eats off the bits of rotting root material that the plant normally sheds. The fungus forms long microscopic chains of cells, expanding the root zone, and taking up nutrients. These nutrients are delivered to the roots, which feeds the fungus with sugars produced by photosynthesis.
Soil and soilless mixes should not be reused. The media hold too many random nutrients and are texturally compromised. To dispose of used soil, let it dry out on sheets of plastic on the floor. Since the soil will probably be in the shape of your pots dues to massive root growth, break up the clumps with your hands as they dry. Remove as much of the root matter by sifting with a screen or manually. Chop up the roots and compost. Spread the soil evenly outdoors in your planters, although be aware that excessive perlite will float to the surface. Otherwise, dispose of the used soil.
Grow bags are cheap and easy to use. The ½ gallon size is perfect for potting up your seedlings or rooted clones. When ready to transplant, water well and let drain, then gently roll the bag between your hands. Slip the ball of soil out of the bag, or cut the bag down its side for easy removal. Grow bags can be used in larger sizes to pot up your plants. The drawbacks with larger sizes are the grow bags are difficult to lift to judge weight and they may tip over with taller plants. Grow bags may be washed in Physan or 10% bleach and reused, but they are so cheap, why bother?
Plastic pots are traditional and allow for an even weight. These pots are inexpensive, easy to lift, and can be redrilled if the drainage is inadequate. After each use, scrub with Physan or a 10% bleach solution, dry and store inside.
Smart Pots, Dirt Bags, or any other brand of these fabric pots are a great improvement over most plastics. If you have ever removed the root ball from a harvested plant’s plastic pot, you have seen a thick root wrapped around and around the outer surface. This is the tap root-seeking newer sources of growth, and it takes plant energy to grow. This happens when small roots hit a barrier and cannot grow outward. A message is sent to the plant that triggers a thicker root to search for more space. Tiny root hairs grow through the fabric pot and are air pruned within minutes. This is like pinching a plant; the side roots start growing without signaling there is an obstacle. The root ball is made of finer roots which fill the container. Some fabric pots have stitched handles. To clean, turn inside out, let dry, and brush off all soil with a small scrub brush. If you notice a white residue on the outside of the pots, wash in a washing machine on gentle cycle, cold water, no soap or bleach. Form into shape, let dry and fold and pack away in a cardboard box inside. These pots are good for 3 – 4 uses.
A bag of soil can also be a container. Open the top cleanly with scissors, fluff up the soil, and punch some holes near the bottom for drainage.
Clay pots are not recommended for indoor work. Porous clay wicks water away from the soil, drying it out quickly. They are heavy, difficult to lift, breakable and expensive.
Whatever container you use, either cultivate the top of the soil frequently to prevent the surface from hardening or top dress the surface with clay pellets or grow stones. This will prevent the crust that causes water to run off the surface and down the inside edge.