Properly caring for your plants throughout each stage of growth can be a difficult process, so what exactly are the basic requirements for growing plants, and what do plants need to grow best indoors?
1) A Proper Growing Medium
Everyone knows that plants can grow in dirt, but did you know there are different types of growing mediums that can help plants grow better?
The growing medium is defined as the material that the roots of a plant grow into. This can take many shapes, forms, and sizes, and include both absorbent and hydrophobic material. New mediums are constantly being introduced to the market, like a ‘spun glass rock’ for example! Some mediums assist in providing nutrients for the plant, but all growing mediums provide a structure that the roots can latch onto to support the plant as it grows.
- Soil is the original growing medium and it has been providing us with high quality crops for thousands of years. In prime conditions, soil naturally contains all of the macronutrients and micronutrients that plants require for healthy growth.
- Peat moss is another common growing medium. Peat moss is mined from peat bogs, a place where layers of dead moss mixed with acidic water to produce peat. It holds 15 - 20 times it’s weight in water and contains lots of nutrients. In general, peat moss shouldn’t be used alone over the long term because it is expensive and degrades over time.
- Coco Coir is the shredded husk (the outside) of a ripe coconut. The long and short fibers (pith) can hold 5 - 8 times it’s weight in water and can hold nutrients to help buffer nutrient swings. This is a great, natural and sustainable growing medium.
- Expanded Clay pellets (Hydroton) are a very popular growing medium. These little potato shaped balls of red clay are heated to 1200°C and expand into a light and airy ball. The pellets absorb moisture and are great for holding lots of oxygen for plant roots.
- Vermiculite is a mineral that is heated until it pops like popcorn, sterilizing it in the process. It absorbs and holds moisture and nutrients very well, like a sponge. This allows it to be a good buffer when there are swings in nutrients. Vermiculite is often mixed with perlite to make a balanced growing medium mix, as vermiculite holds water, and perlite oxygenates.
- Perlite is a mined volcanic material that is heated until it melts and expands up to 20 times its original volume. It contains tiny bubbles in each piece, and air is stored in those tiny pockets, making it a good, airy growing medium that helps with draining when mixed with coir or soil. If you decide to work with perlite, make sure to wear a face mask as perlite dust is bad for your health.
- Rockwool is basalt and chalk melted together and then spun into long strands, similar to the way you would make cotton candy. It holds up to 18% air even when fully saturated and is a great solution to deliver both water and air to the roots. Rockwool is great for germinating seeds.
- Growstone is made from 98% recycled glass that has been crushed into a powder then mixed into a slurry and placed in a kiln. Once cooled, it cracks and is broken into smaller pieces that are reusable and inert.
Many grows also mix and match together growing mediums to get the best out of each medium's properties. For example, you can mix coco coir and perlite together so that the mix holds large amounts of water and is well aerated.
The growing medium that you choose to use will depend on the types of plants you wish to grow. Water loving plants like tomatoes or strawberries would appreciate having vermiculite to grow in, as this growing medium holds large amounts of water. On the other hand, you may want to mix in more perlite for plants such as cacti, which prefer to dry out between waterings. A great medium for cannabis is coco coir, as it drains well, hydrates easily, and allows lots of room for air. There is no established "best medium", so experiment with your mediums and see what works best for you and your plants!
Plants require a myriad of nutrients to grow and thrive. Some are basic and can be found by the plant with little effort from the gardener, but some are more specific, and supplementing your watering schedule with macronutrients or micronutrients becomes essential.
Basic Plant Nutrients
Carbon, Hydrogen & Oxygen - available to plant through air, soil & water naturally.
Nitrogen, Phosphorous & Potassium (NPK) - NPK’s are the primary food for most plants and they require a lot of it. These nutrients need to be added to the plant's soil or water for healthy growth.
Calcium, Magnesium & Sulphur - Not the focus of most nutrient formulations, as plants require less of the secondary nutrients in comparison to the primary, but they are still essential for healthy plant growth.
Iron, Manganese, Zinc, Copper, Boron, Molybdenum, Chlorine - Not the focus of most nutrient formulations, and plants only require trace amounts for healthy growth.
The main difference between macronutrients and micronutrients when it comes to growing plants is the quantity the plant needs. All plants require larger amounts of macronutrients, while only needing small amounts of the micronutrients.
For the indoor gardener, light is the most important factor to consider since we are trying to bring the sun inside. Traditionally, HID (High Intensity Discharge) lights like a 1000 watt High Pressure Sodium or Metal Halide are used in a grow tent, but due to the excess heat they generate, a venting solution must also be in place, and that costs extra money and effort.
Often, growers will start their plants under a Metal Halide bulb that offers more in the blue light spectrum during the seedling and vegetative stage of growth. Once the flowering stage is triggered, the bulb is replaced for a High Pressure Sodium bulb, that more closely reflects the autumn sun with a more red spectrum.
The most versatile lights are LED (Light Emitting Diodes) lights, as they are able to mimic all of the colours across the spectrum, so you don’t need to change them out if you are able to adjust their colour.
HPS (High Pressure Sodium) - Can be used for full cycle growth but especially favoured during the flowering stage because its light can easily penetrate a plant canopy. It has a great light colour spectrum, but it uses a lot of electricity and produces large amounts of heat that must be vented. For further information on HPS.
MH (Metal Halide) - Used for seedling & vegetative growth. It can produce blue light, but also gets very hot and uses a lot of energy. For further reading on MHs.
CFL (Compact Fluorescent) - Produces little heat, and uses less energy. Only used for cuttings or seedlings due to its low light intensity. For further reading on CFLs.
LED (Light Emitting Diode) - Highly efficient, it consumes little energy and produces less heat. Adjustable colour spectrums means no changing out of bulbs is required. For further reading on LEDs.
4) The Perfect Environment - Temperature & Humidity
When growing indoors, temperature and humidity are both factors to keep an eye on. Plants in general like a temperate climate, with some varieties enjoying it a bit warmer as they are used to living in a warm area.
In an effort to encourage strong stem growth, exposing your plants to a gentle breeze is required. You can mimic the wind by setting a small oscillating fan next to your plants, or pointing your fan at the wall so that there is an indirect breeze. Too much constant wind will stress your plant and stunt its growth.
An oscillating fan helps strengthen plant stems.
Similarly, in an effort to reduce odours, a carbon filter is recommended. You will need fresh air flowing in, and old hot air flowing out through a ventilation system with an inline fan. This airflow will also reduce mold, replenish the air, and stabilize humidity.
5) The Right Amount of Space
The general rule of thumb is that you need 50 watts of HID light for every square foot of grow space you will be utilizing.
200W = 2’ by 2’ area
450W = 3’ by 3’ area
600W =3.5’ by 3.5’ area
800W = 4’ by 4’ area
There is certainly much to think about when starting down the gardeners trail, so don’t get overwhelmed. You may not get everything perfectly dialed in on your first try, it almost never goes perfectly the first couple times. Nature is on your side and most things really do want to grow, you are just there to be their tender and guide.