How Much PPFD Do Cannabis Seedlings Need?

PPFD stands for Photosynthetic Photon Flux Density. It is a measure of how many photons of light in the photosynthetically active radiation (PAR) range (400-700 nm) hit a square meter of surface per second. PPFD is measured in micromoles per square meter per second (µmol/m2/s).

PPFD is important for growing cannabis indoors because it tells you how much light your plants are receiving at different stages of growth. Different stages of growth require different levels of light intensity to optimize photosynthesis and plant health.

Cannabis seedlings are young plants that have just sprouted from seeds. They are very delicate and sensitive to environmental stress. They need enough light to grow strong stems and leaves, but not too much that they get burned or stressed.

According to several sources , cannabis seedlings require only **200-300 PPFD** during the first three weeks of life. This level of light can easily be achieved with most grow lights. Make sure you hang the grow light at the correct distance from the seedlings.

To calculate how much PPFD your grow light delivers at a certain distance, you can use a PAR meter or an online calculator. You can also check the manufacturer's specifications or reviews for your grow light model.

If you don't have any tools to measure PPFD, you can use your hand as a rough guide. Place your hand under the grow light at the same height as your seedlings. If you feel a slight warmth on your hand, that's about 200-300 PPFD. If you feel a strong heat on your hand, that's too much and you need to raise your grow light higher.

As your cannabis seedlings grow into vegetative and flowering stages, they will need more PPFD to produce more biomass and buds. The recommended PPFD for vegetative stage is **400-600 µmol/m2/s**, and the recommended PPFD for flowering stage is **800-1000 µmol/m2/s**.

However, these are general guidelines and may vary depending on other factors such as strain, temperature, humidity, CO2 levels, etc. You should always monitor your plants' health and adjust accordingly.

PPFD is one of the key factors that affect cannabis growth indoors. By providing optimal PPFD levels for each stage of growth, you can ensure healthy and productive plants.