Growing Arabidopsis thaliana in substrate requires careful attention to watering and fertilization to avoid overwatering, nutrient imbalances, or stress. Here are some tips to help you with this process:

1. Watering Arabidopsis:

• Frequency: Watering should be done once the top layer of the substrate is dry, but avoid letting the substrate dry out completely. Typically, this can be every 2-3 days, depending on the humidity, temperature, and substrate type.
• Amount: Provide enough water to moisten the substrate without waterlogging it. Use a spray bottle or a watering can with a fine nozzle to ensure even distribution and prevent disturbance of the small seedlings.
• Method: Bottom watering is ideal for Arabidopsis to avoid damaging the delicate seedlings. Place pots in a shallow tray with water, allowing the substrate to absorb moisture through the drainage holes. Remove the pots after about 10-15 minutes to prevent over-saturation.

2. Fertilization Arabidopsis:

• Type of Fertilizer: Use a diluted balanced liquid fertilizer (e.g., 1/4 to 1/2 strength of a general-purpose fertilizer like 20-20-20 or similar). Arabidopsis does not require high nutrient levels.
• Frequency: Start fertilizing 1-2 weeks after germination and continue every 2-3 weeks during the vegetative growth phase. Avoid over-fertilizing, as it can cause salt buildup or stress.
• Method: Apply the fertilizer through the water used for bottom watering, ensuring even distribution without direct contact with leaves.

Additional Tips:

• Substrate: Use a light, well-draining substrate like a mix of peat and sand or commercial seed-starting soil.
• Drainage: Ensure that pots have adequate drainage holes to prevent waterlogging.
• Environmental Conditions: Maintain moderate humidity, with temperatures around 22–24°C during the day and slightly cooler at night. Ensure good airflow and light (e.g., 16-hour photoperiod with fluorescent or LED lights).

Thank you very much Raghad Mouhamad !