Over the last two years, I’ve delved into cultivating a variety of plants. Most of them cactus, some are succulents, some are… every other kind of plant.

This is an entry post detailing what I’ve learned about what plants need. This will set the stage for future posts more specific on growing cacti.

Air

Air is important for both the foliage of the plant and its roots. Besides the gasses that leaves breath in when the stomata are open, the leaves require air/air movement to induce transpiration. AKA, the water passively lost to the air will lead to the plant drawing up more water and nutrients.

Air movement is also important to reduce the chance of a fungal or bacterial infection. Air movement will evaporate any residual moisture on the leaves which would otherwise become a breeding ground for bacteria.

Air (oxygen) is important for the roots. What we all know about “root rot” or “overwatering your plant” often goes unexplained. Basically, root rot is caused by an organism that used to be classified as a fungus (but is no longer.) It is an opportunistic pathogen that will overtake the root material provided there is not enough oxygen (water will deprive the roots of oxygen.)

This is essentially the reason most plants want loamy, fluffy soil with good drainage. That, and compacted soil is difficult for roots to penetrate and often hydrophobic, not easily saturated with water.

Substrate & Nutrients

Soil is the natural substrate of many plants, but not all. Some instead grow on trees with exposed roots, like orchids. Organisms in soil process and breakdown organic matter, offering things a plant needs in exchange for the plant returning carbohydrates.

Strictly speaking, many substrates we use do not classify as “soil.” These substrates would include coco coir and peat moss. Coir and peat moss are considered inert, that is, they do not have any immediate nutritional value to the plant. This is why many indoor plants require regular fertilization - they don’t have the full soil ecosystem that an in-ground plant would.

As it happens, inert substrates are very useful to a grower, especially indoors. Fungus and mold easily grow in compost humus-rich soil. By using a less nutritious and bioactive soil, you reduce the chances of many plant pathogens and other stuff that you don’t want sporulating in your home!

Sprouts and seedlings require little to no nutrition from a substrate. This is why you can germinate seeds on a paper towel. Inert media is helpful in the process of germinating cacti seeds although not 100% necessary.

Water

Water is a solvent. Many things are at least partially water-soluble. Solubility is affected by pH, that being the alkalinity or acidity of a soil. Different plants are accustomed to a certain pH - cacti that grow in limestone rich environments appreciate a substrate with higher pH. Generally, the higher the pH the less nutrients are available to a plant, which affects how the plant looks and its growth speed. Certain cacti, when grown in a more neutral substrate, start to balloon: and lose their recognizable characteristics: but will grow faster and look “healthier” to the inexperienced eye.

Good and bad bacteria appreciate water. The microorganisms in a pot will fluctuate between activity and inactivity based on the conditions they are subjected to. It is common that plants will grow faster when watered frequently, provided that their roots receive enough oxygen.

It is true that growing a plant in a pot will never be equivalent to growing a plant in the ground. Many aspects are different - the way the water drains, the wet-dry cycle we subject plants to, the finite resources available in a pot.

Sun

Plants need the sun. Not all life requires the sun, at least directly. Ghost pipes and most (all?) fungi lack the chlorophyll necessary to process sunlight. The sun is not a static and easily defined light source. In fact, many characteristics of the sun are difficult to replicate with growlights. Growlight effectiveness is variable. Even shaded outdoor areas may provide more light to a plant than being blasted by LEDs.

Two big factors for a plant are how diffused the light source is and how long it is exposed to light. In the outdoors, light is bouncing off of everything, so a plant can be adequately supplied without being in direct sunlight. Many plants are adapted to this, like plants that grow along the forest floor. This is extremely difficult to replicate with growlights.

Temperature

Plants need established root systems to keep cool. In hydroponics, the ideal water temperature is between 65 and 80 degrees Fahrenheit (these numbers vary slightly depending on who you ask.) Besides keeping cool, having established root systems in-ground allow many plants to tolerate temperatures that would otherwise kill them in a terracotta pot. I know this from personal experience… I lost 2 venus flytraps to winter. Had I mulched, they would have made it.

Thanks for reading!