After germination, the marijuana plant enters the seedling phase. In this article, we’ll cover how to take care of your seedlings, potential issues that may arise, and how to handle them.
Marijuana seedlings like moist conditions. They need warm temperatures and close proximity to lights, which should be adjusted as the plants grow taller. Seedlings also need minimal nutrient intake and will require more as they get larger and stronger.
Seedling Phase (2 to 3 weeks)
When a marijuana seed opens, it produces a pair of leaves called “cotyledons.” Next, the plant generates serrated leaves, not the distinctive digitate leaves with multiple serrated leaflets. As the plant continues to grow, it will produce new leaves with more leaflets until the plant develops digitate leaves with serrated boundaries that are easily recognizable as marijuana fan leaves. This stage can take up to three weeks.
Factors for Healthy Marijuana Seedling Growth
Warm Temperature: Seedlings are sensitive to temperature, and they’ll thrive in temperatures around 72-79°F (22-26°C).
Moderate Light Intensity: Young plants are not ready to process high-intensity light just yet. Consider LED lights or low-wattage lights. A blue range light is better at promoting vegetative growth.
Appropriate Light Distance: Be mindful of the distance between the plant and the grow lights, which varies according to their strength and temperature. If using low-intensity lights, start with a 4-inch (10 cm) distance and do the “hand test” by placing your hand on top of the plants for 30 seconds. If it feels too hot for your hand, it’s too hot for the plant. Move the lamp further away until it’s warm, not hot. When growing outdoors, place your plants in the sunniest spot and ensure the soil never dries out.
Light/Photoperiod: Begin with 18 hours of light and 6 hours of darkness.
Nutrition: Seedlings need a low amount of nutrients; too much nutrient intake leads to nutrient burn. If growing on soil, choose light blends and avoid extra fertilization in the first week or two. After that, start your feeding plan.
Pot Size: Start with a small pot or cup with drainage holes for best results. Once it grows a bit or when roots start coming out of the drainage holes, move the seedling to a bigger pot.
Watering: To avoid overwatering, spray water around the seedling using clean water only.
Relative Humidity: Too dry an environment may cause your seedling to dry out fast, so maintain it at around 65-80%.
pH Levels: Maintain pH levels between 6.5 and 7 to help your seedling absorb nutrients present in the soil.
Stunted Growth in Marijuana Seedlings
Is your marijuana seedling not growing? Some factors may result in stunted growth in the seedling stage:
Problems with Watering and Pot Size
Both overwatering and underwatering may cause stunted growth. Also, small seedlings in big pots may lead to overwatering. In this case, the plant will look sagging and weak. To fix it, add less water and only around the seedling. Let the plant soak up the water before watering again. Meanwhile, planting small seedlings in too small pots may stunt their growth. In this case, transplant the seedlings to larger pots. Poor drainage might also lead to the same issues.
Problems with Nutrients
Nutrient toxicity happens when the growing medium has too many nutrients for the stage, and the plants can’t absorb them. You’ll notice burnt tips and dark green leaves. On the other hand, nutrient deficiency may occur when there are no nutrients in the mix or when there are too many nutrients, and pH levels are unbalanced such that the nutrients are unavailable. The most common nutrient deficiency at this stage is nitrogen deficiency, which shows when older leaves turn yellow, then brown, and become dry to touch. In some cases, the plant may use all the nutrients from the soil and outgrow it. To fix this, transplant it into a larger pot with soil mix and nutrients for the vegetative stage. Watch the water schedule for better results.
Problems with Temperature
Temperatures that are too high or too low may lead to stunted growth. When the temperature is too high or too low, the tips of leaves start appearing and curling. It’d be best to lower or increase the environmental temperature and monitor the changes. Keep the temperature between 72-79°F (22-26°C).
Problems with Light
Too much or too little light may cause stunted growth in marijuana seedlings.
Plants lacking light will grow tall and weak with a few leaves, and their stems will grow tall and white. Reduce the light distance to fix this issue. Remember to do the “hand test.” When the plant is exposed to too much light, the leaves curl and appear burnt. You need to move the lights further away and do the “hand test” to fix it.
Take Care of Your Cannabis Plants!
Marijuana plants are sensitive and vulnerable in the seedling stage. They require special care, minimal watering, and a humid environment since their root systems aren’t fully developed. A healthy marijuana plant has green leaves and a short stem. Keep an eye on the environmental elements. You can download Grow with Jane, our free app, to monitor your plant health.
If you follow these guidelines, your seedling will quickly grow into a healthy plant in the next stage, and you’ll notice digitate leaves with serrated edges.