An increasing number of marijuana growers prefer hydro mixtures to the traditional soil. Hydro mixtures are better for indoor cultivation as they allow to control the amount of water and nutrients added to the plant. These potting mixtures are less likely to develop mold or insects, so growers have more chances to cultivate healthy plants and get high yields.
Mineral wool is very similar to fiberglass but is produced from spun molten limestone. This mixture has impressive water-absorbent properties and can store water for a long time. Mineral wool is often used by advanced growers, as beginners find it difficult to deal with.
Mineral wool provides roots with moderate buffering, so the correct dosing of nutrients is essential with this kind of medium. Beginners also worry about algae growth and salt build-up that sometimes happen with plants growing in mineral wool. In order to avoid these side effects, keep your plant's roots away from light, make pure-water flushes once a week, and maintain a 5.5 pH of the mineral wool. This potting mixture is the most effective for flood-table systems or flood-and-drain setups.
Soilless mediums for marijuana plants are based on sphagnum, coco, or peat. Due to organic amendments like wood chips, bark, and perlite, such mixtures are well-draining but still water-retentive. Moreover, soilless mediums are less prone to getting pests and bacteria. Advanced growers create their own soilless mixtures by combining the base medium with other compounds in their own ratios.
Soilless mixtures are commonly used instead of standard topsoil for indoor growing. Growers use them for planting marijuana seeds in top-feed drip- or spray-emitter systems that can equally saturate the potting mix. However, soilless mixtures consist of small particles of matter, so it is hard to use them for flood-and-drain or deep water culture systems.
Pop clay, or hardened expanded clay, consists of small pieces of clay processed at extremely high temperatures. For marijuana growers, it provides a vast variety of benefits. These small brown marbles are affordable, reusable, and free of any contamination. The medium provides the plant's roots with enough oxygen and holds enough moisture for healthy watering and nutrient supply. Pop clay is great for plant stabilization in flood-and-drain systems and other setups as well.
However, pop clay does not provide much buffering, so there is a risk of burning the plants with excessive amounts of nutrients. Thus, if you choose this type of mixtures, you should know the exact doses of nutrients necessary for your weed plants. Keep in mind that top-feed systems may leave dry areas in this medium, which may make it difficult for pop clay to supply enough water to the plant's roots.