How To Grow Cannabis Seeds Indoors

Correct Lighting.

Your plants need sufficient levels of light for growth. During the early, vegetative stages, Metal Halide (MH) bulbs are preferred, emitting a ‘blue-light’ spectrum. As the plants begin to flower, these bulbs are often swapped for High-Pressure Sodium (HPS) bulbs, which produce a warmer, ‘red’ spectrum of light. By switching between the two bulbs, you can enhance both the vegetative growth and flowering phases of the plants development.

More watts equal a bigger harvest. Many new and beginner growers underestimate how much light their plants need. Given good conditions, growers can harvest up to 1-gram of dried bud, per watt, per square meter. Growing in a larger area, without sufficient light, won’t increase your harvests. A 600 watt lamp produces a greater intensity of light, than a 400 watt unit and is able to penetrate further through the plant canopy.

Do not allow the growing tips to get too close to the lights. The height of your lamps will need to be altered at various stages of the plants development. If the plants gets too close, the heat will burn them. However, too far away and they will stretch, requiring training to produce an even canopy.

Ventilation and Air-Flow.

If you’re growing within an enclosed area, good air-flow and ventilation is vital. The air within the grow-room needs to be expelled and replaced on a regular and constant basis. Grow lamps emit a lot of heat and the more lights, the greater the heat build-up. Cannabis plants grow best in temperatures of between 70 – 85 degrees Fahrenheit. Try to maintain an even temperature both day and night. Replace the air using both intake and exhaust fans.

Oscillating fans at various heights, help improve air-flow. Cannabis plants intake air through their leaves. They use the CO2 for growth and respiration, expelling unwanted oxygen. Without movement, the air across the leaves can quickly become stale, restricting intake and slowing growth. Air-flow around the plants from the seedling stage, will help to strengthen the stems and branches, increasing nutrient uptake.

During the Winter months, night-time heating may be required. If the temperature in the growing area drops below 60 degrees, plant development and bud growth will slow down. However, cooler night-time temperatures during the last two-weeks of maturity can enhance the purple coloring of strains such as Granddaddy Purple.

Humidity Control.

Cannabis plants transpire, expelling water-vapour through their leaves. Growing within an enclosed area, without adequate ventilation, will cause the humidity levels to rise significantly. Once these levels become too high, they can cause a host of problems and issues, culminating in water dripping down the walls and causing mold and bud-rot in later flowering.

Fit a humidity sensor in your grow room and try to control the levels during the various stages of the plants development. Young seedlings enjoy higher levels, with best results achieved between 60% – 70% humidity. This should be decreased during the vegetative stage to between 40% – 60%. Flowering requires the lowest levels, between 40% – 50%, which should be reduced even further as harvest-time approaches.

High humidity levels cause more problems than low humidity does. Growth and development is reduced, while creating the perfect environment for mold, bud-rot and attacks from pests. A small dehumidifier can quickly and cheaply reduce these issues, producing greater harvests through better control.

Pot Size and Growing Medium.

Choose the right sized pot for your growing style. The bigger the plant, the larger the pot will have to be to accommodate an adequate rooting system. Screen-of-Green growers often cultivate large plants in big pots. While the Sea-of-Green method requires smaller pots, but more of them.

Ensure there are plenty of holes for excess water to drain away. A common mistake made by new growers is to over-water their plants, drowning the roots and making the growing medium too heavy for the roots to develop easily. A saucer or tray under the pot will capture any excess, but do not allow the pot to stand in water for too long.

Your growing medium needs to be light, aeriated and fluffy. A variety of high-quality mixes can be purchased, or mixed individually using a variety of ingredients. These can including; perlite, vermiculite, worm castings, bat guano, coco fibre and more. A good quality mix can provide all the plants require, during the early stages of development.

Watering and Nutrients.

Your plants will require a selection of nutrients and minerals for fast-growth and superior flowering. Do not be tempted to feed your plants too much. More nutrients doesn’t mean more growth or bigger buds. In fact, it has the opposite effect, resulting in problems such as Nitrogen burn and overdose. Or blocking the intake of another mineral, causing other, harder to detect issues.

Keep the growing medium moist, but do not flood or over-water the plants. Small, young seedlings do not require large amounts of water. Roots should be encouraged to develop and seek-out moisture. A root-booster can be applied during the early weeks, but avoid high levels of nitrogen during this stage.

Your plants will require a variety of different nutrients as they begin to flower. Use a good quality additive to supply the plants all they need. Follow suggested feeding patterns and schedules and always check the Ph levels before adding. Feeding the plants with too acidic, or alkaline water, will reduce the plants uptake, resulting in slower growth.

Pests and Diseases.

Spider-mites are one of the biggest, ‘problem-pests’ faced by indoor Cannabis growers. Tiny and almost undetectable at first, they quickly multiple and cause an infestation. To begin, they live on the underside of the leaves, sucking liquid from the blades. As they increase in numbers, they build webs across the buds, and are very difficult to eradicate.

Poor ventilation, uneven temperatures and high humidity are the perfect breeding ground for bud-rot and mold to develop. Fungus spores build-up within the deep parts of the bud, destroying it from the inside, outward. Once it has taken-hold, the only option is to cut-away and remove the affected buds, harvesting the remaining ones as soon as possible.

Root-rot is an often unseen problem, undetectable until it’s too late. Instead of a healthy rooting structure, the root-mass breaks-down, becoming a mulch of rotting mess. The plant’s ability to intake nutrients is severely reduced, often causing it to die. Allowing the roots to stand in water, or constantly over-watering the growing medium, is the most common cause.

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