Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

The answer is simple. Mix the fertilizer as per the instructions and water as normal, or dilute the fertilizer and apply it more often. Many liquid fertilizers are very diluted already. Consider using more concentrated fertilizers whenever possible. Remember, small plants use much less fertilizer than large ones. Fertilize early in the day, so plants have all day to absorb and process the fertilizer.
    It is difficult to explain how often to apply all fertilizers in a few sentences. We know that large plants use more nutrients than small plants. The more often the fertilizer is applied, the less concentrated it should be. Frequency of fertilization and dosage are two of the most widely disagreed upon subjects among growers. Indoor containerized marijuana can be pushed to incredible lengths. Some strains will absorb amazing amounts of fertilizer and grow well. Lots of growers add as much as one tablespoon per gallon (15 ml per 4 L) of Peters™ (20-20-20) with each watering. This works best with growing mediums that drain readily and are easy to leach. Other growers use only rich, organic potting soil. No supplemental fertilizer is applied until a super bloom formula is needed for flowering.
    Fertilizing plants in the ground is much easier than fertilizing containerized plants. In the soil outdoors, roots can find many nutrients, and fertilization is not as critical. There are several ways to apply chemical fertilizer. You can top-dress a garden bed by applying the fertilizer evenly over the entire area. You can side-dress plants by applying the fertilizer around the bases of the plants. You can foliar-feed plants by spraying a liquid fertilizer solution on the foliage. The method you choose will depend upon the kind of fertilizer, the needs of the plants, and the convenience of a chosen method.

This Grow Schedule by Hesi details the exact feeding schedule for a super successful crop.

This ‘Haze’ plant is hypersensitive to fertilizer. Leaves curl when given slight overdose.

All leaves in this photo came from the same plant. All leaves show signs of overfertilization.
    When using synthetic fertilizers, it is extremely important to read the label carefully, and follow the directions. The initials “WSN” and “WIN” that you may see on the label stand for water-soluble nitrogen and water-insoluble nitrogen. WSN dissolves readily, and it is considered a fast-release nitrogen source. WIN does not dissolve easily. It is often an organic form of nitrogen and is considered a slow-release nitrogen source.
    Use a siphon applicator-found at most nurseries-to mix soluble fertilizers with water. The applicator is simply attached to the faucet with the siphon submerged in the concentrated fertilizer solution with the hose attached to the other end. Often, applicators are set at a ratio of 1 to 15. This means that for every 1 unit of liquid concentrate fertilizer, 15 units of water will be mixed with it. Sufficient water flow is necessary for the suction to work properly. Misting nozzles restrict this flow. When the water is turned on, the fertilizer is siphoned into the system and flows out the hose. The fertilizer is generally applied with each watering, since a small percentage of fertilizer is metered in.
    A garbage can with a garden-hose fitting attached at the bottom that is set 3-4 feet (90-120 cm) off the floor will act as a gravity-flow source for the fertilizer solution. The container is filled with water and fertilizer.
    When it comes to fertilization, experience with specific varieties and growing systems will tell growers more than anything else. There are hundreds of N-P-K mixes, and they all work! When choosing a fertilizer, make sure to read the entire label, and know what the fertilizer claims it can do. Do not be afraid to ask the retail clerk questions or to contact the manufacturer with questions.
    Once you have an idea of how often to fertilize, put the garden on a regular feeding schedule. A schedule usually works very well, but it must be combined with a vigilant, caring eye that looks for over-fertilization and signs of nutrient deficiency.
    Leach soil with 1-2 gallons (4-8 liters) of mild nutrient solution per gallon of soil every month. This is the best form of preventive maintenance against toxic salt buildup in the soil.

Spray foliage from underneath so the spray is able to penetrate the stomata located on the leaf’s underside.

Leaves and stalks have waxy, cystolith hairs that act like