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Watering 101

While grow lights and tents are extremely important tools of the indoor grower, the nutrients you use, the media that your roots spread into, and the method of how you water are just as important as controlling your environment. Before we can even start to water, we must know WHAT media we are growing in.

Growing Media Options:

Living Soil

There are many pieces to this type of media. The soil does not need any nutrients, just water. Essentially, living soil involves various organisms (bugs, plants, micro-organisms, etc.) all living together in your soil and they create the nutrients necessary to feed the plants.

This is one of the cleanest types of media and you can juice and eat the raw cannabis leaves.


Soil is either prepared by the grower or purchased in bulk from a distributor. Soil can contain all the nutrients necessary to grow a plant for 3-6 weeks, or a very light soil that needs nutrients added from day one.

Growers choose soil because it is much more forgiving when dealing with feeding, moisture loss, and PH balance. Some growers will tell you that soil makes the flowers smell and taste better.


Coco Coir is made up of coconut fibers that have been torn from the outside of the shells. This medium retains water well, drains and aerates efficiently. Coco is a PH-neutral medium and retains a ph between 5.2 and 6.8. You can reuse coco after you wash it.

Hydroponics and Coco both boast fast harvests that yield well. However, if you over nute, under nute, or mess up your PH levels, you can nuke your plants quickly. You may need to use specific nutrients for coco because the fibers can hold on to Calcium, Magnesium, and Iron and not allow uptake into the roots.


We will be using a soil coco mix. I like the properties of coco, but I also like the buffer that soil provides. For novice home growers, I recommend using only soil, or a soil/coco mixture at a 1:1 ratio.

When you water, you should water based on soil, and not coco.


Rockwool is a rock-based mineral fiber that we can use to grow in. It is made up of Basalt (Volcanic Rock) and Recycled Slag (By-product of the steel and copper industry). (

When using Rockwool, the cube does not hold nutrients, but the fibers allow the roots of the plant to adhere themselves and create a solid root mass. This medium holds water, but if it dries out, it can be catastrophic, so most growers have some type of automatic drip attached to each cube.


Growing without soil. The roots are suspended in water. The nutrients are added via reservoir and everything is controlled via the watering source. PH and PPM are constantly monitored.


Growing without soil. The roots are suspended in air, but sprayed with nutrient enriched water sources. PH and PPM are constantly monitored.


When you combine hydroponics and aquaculture, you get aquaponics. Like living soil, the plants are fertilized by the excrement of the fish and beneficial plants living in the aquaculture. You should be able to juice and eat the raw leaves of the cannabis grown in this medium.

The Lucas Formula

Because General Hydroponics products are cheap and proven to work, I will be using the Lucas Formula to grow using only the Bloom and Micro Bloom.

The Lucas Formula is very simple:

  1. Bloom at 16ml per Gallon of Water

  2. Micro at 8ml per Gallon of Water

This is all you need from veg to flower. We all wish this was totally true, but you must add some pieces to the puzzle to make it all fit together.

What Type of Water?

If you have access to Reverse Osmosis water (R/O Water), that is the best water that you can use because it is pure water that should have all of the impurities removed. The PH moves VERY fast when adding nutrients compared to tap water. When filtering R/O water, there is a lot of waste, but you have a very clean product for growing your cannabis. Because you have stripped everything out of your water, you must now add calcium and magnesium to every watering. Most of us do not have an R/O system installed at our house, but we may have access to filtered water.

If you decide to use filtered water, you may still need to add calcium and magnesium. Filtered water is good to use because it has removed the chlorine from the water. The drawback from using filtered water, is that it also removes some minerals from the water. This is the second-best option for watering your plants.

The last option is tap water. While using tap water should be your last option, you need to ensure that you leave the water out for at least 24 hours before watering your plants. The city water is usually super high in chlorine and if you leave the water out, the chlorine should evaporate out. Before using your straight tap water, check the ppm of the water from your local water company. Know what you are putting in your plants before you load up the ppm with more nutrients and then overload their systems. The water in your tap should contain ample calcium and magnesium so you should not have to add any to your nutrient system.

Watering Your Plants

For this watering method we will be focusing on a soil or soil/coco growing media. From the time your plants take root, you need to start feeding them. Based on the Lucas Formula and some necessary additives, we can create a simple watering plan. Because we do not want to feed too much too fast, a watering schedule of water – nute – water – nute gives the plant a chance to use all of the nutrients stored before being fed again. This watering schedule does not mean that you water every day, watering your plants should occur when they are thirsty.

Vegetative Nutrient Schedule:

Add all of your nutrients into your water at the prescribed ratios and mix well. After the nutrients have been thoroughly mixed, check the PH of the mixture. If the PH is off, adjust accordingly before watering your plants. It is imperative that the PH is within the desired range to ensure that your plants can take in the nutrients effectively. Check the EC or PPM of your water so that you do not overcharge your plants. It is okay to push your plants, but not okay to burn them.

The method for using these types of nutrients is called drain-to-waste. This means that you must water thoroughly and ensure that you have 10-20% drainage. In order to water without wasting your new nutrients, I begin with a half-gallon of clean water to start the drainage. After I run the clean water, I will then pour 1 full gallon of nutrient water into the pot. There should be minimal drainage. After 1 hour, I come back and put another half-gallon into the pot. At this time there should be drainage. Use a drip pan with risers to avoid having the plant sit in the wastewater.

The greatest take away about watering your plants, is to not over feed, over water, under water, or under feed. That seems like a lot to handle, but stick to the method and you will be fine:

  1. Water when thirsty: Pick up the pots when they are empty to know when they need to drink. You can easily over water a plant if you continuously water before it finishes the last drink.

  2. Alternate Feed and Water days. Let the roots rest and take in the rest of the nutes locked in the soil before feeding again. On non root feed days, throw in a foliar feed and spray some seaweed (Algas Pacific – Npkelp) on the leaves upon wakeup.

  3. Check your PH before watering. Ensure you are watering with the cleanest water possible.

  4. Watch your leaves: Your plant will tell you what is wrong. Watch for discolorations and curling leaves. Make small adjustments to fix the deficiencies.

The plants in our grow have a few weeks left before we flip them into flowering mode. When we do, we will add a few nutrients to boost at certain times in the grow cycle. Get your vegetative growth full and healthy now so that flowering will be smooth and hearty.



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