Timing when to add nutrients to your indoor flowering plants doesn't need to be a mystery. Most growers add nutrients at every watering, but the ratio of nutrients in their fertilizer will change depending on the developmental stage of the plant.

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Nutrient for Vegetative Plants

Some growers opt to start their plants off on a light fertilizer for one week just when their seedlings start to enter their vegetative growth phase. This step can be a great way to introduce your plants to their fertilizer and avoid nutrient burn. However, some growers see great results immediately starting their plants on a nitrogen heavy fertilizer to kickstart growth. It’s often dependent on the plant variety or strain.

By the mid-vegetative phase (roughly 6 weeks after germinating), you’ll want to aggressively increase your plants’ nutrients to help them develop strong, healthy foliage. Most growers are still using their nitrogen heavy veg fertilizer in this stage. These heightened levels of nitrogen will help your vegging plants produce luscious, green foliage and develop plenty of bud sites in time for flowering.

Towards the end of the vegetative phase, it’s a good idea to start lowering your nitrogen levels and preparing your plants for the switch to their bloom booster.

Nutrients for Flowering Stage Plants

Flowering cannabis plants need less nitrogen and more potassium to promote the growth of big, resinous flowers. During the first two weeks of flowering, most growers feed their flowering plants with a low nitrogen/higher potassium fertilizer. From here on out, it’s common practice to keep dialing up the nutrients on all fronts, always keeping potassium concentrations higher than the rest.

During the last weeks of flowering, growers will drive down their nutrients to smooth out the transition to the pre-harvest flush. About 1-2 weeks out from flower you water the plant with plain water until it’s finished!

Preparing Your Nutrients

Always follow the instructions on your nutrient bottle, as well as consult the guidance of professional growers!

  1. Prepare your water first by making sure it’s room temperature and not ice cold from the faucet. Many growers will let it sit out for 24 hours.
  2. Follow the instructions on your fertilizer to add nutrients, and stir. To get accurate readings, use a PPM or EC meter.
  1. Use a nitric or phosphoric acid pH down supplement to adjust the pH of your feed if required.
  2. After you've got your PPM, pH, and temperature settings correct, feed your plants and measure runoff with a PPM or EC meter to verify they're absorbing their nutrients properly.

If you have questions, Happy Hydro can help!

Author | Chris McDonald

With two decades of expertise, Chris leads Happy Hydro in redefining sustainable gardening and delights in backpacking adventures, mind-expanding journeys, and creating memories with his loved ones.

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