Caring for Cannabis Indoors During the Vegetative Phase

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Caring for your plants through the vegetative phase in an indoor grow requires its own little protocol. In the veg phase, your plant is focused on leaf development and getting stronger. A reasonable time to start thinking about the veg stage is in the second to third week after germination. First you need to plan your space to make sure you have enough height and girth around your plants to accommodate their new growth.      

This article goes over the basics of how to grow marijuana during the veg stage. You can also check out the more thorough grow articles on the ACMPR license blog at Cannabis Growing Canada.

Soil for Repotting Cannabis Seedlings

Here’s the suggested course for soil and repotting your seedling. Take a five gallon pot with good drainage and fill it with a mix of organic super soil. You want a soil with a healthy flora of microorganisms. Basically, with a good organic soil, the microorganisms actively breakdown organic matter in the soil providing your plants with a continuous new supply of nutrients. What this means is you don’t need to add additional fertilizer during the veg grow stage.

Here’s one recipe for the soil:

  • 1 part compost
  • 1 part perlite
  • 1 part coco coir
  • Humic acid: 1/4 cup for every 5 gallons
  • Kelp meal: 1/4 cup for every 5 gallons
  • Endomycorrhizae powder, called Mycorrhizal inoculant, ¼ to ½ tsp/gallon
  • Bat guano, up to 5% total substrate
  • Worm castings, called Vermicompost, up to 20% total substrate

Water your soil some, ensuring not to overwater. Then make a hole in the soil the same size as the pot your plant has come from and plunk in your plant.

A trick to getting your plant out of it’s seedling pot, that is if you’re using a plastic pot, is squeeze the pot around the sides. Then whe you up-end it, the plant will slide right out.

After placing your plant in the new pot, simply fill in any extra space with dirt, covering all the roots. Now your plant is ready to spread out and stretch to its optimal dimensions ahead of the flowering stage.

Lighting and Environment for Indoor Cannabis Plants

The next thing to talk about is grow lights because we’re not growing in a greenhouse or outdoors. Indoors gives you the most control over your environment, including lights, humidity and temperature, and also it’s easier to control for pests. The downside is the extra cost for equipment.

One lighting solution for the veg stage is a ceramic metal halide. This light source is like springtime for your plants. Think blues as well as yellows as your seedlings grow, build foliage and strengthen their limbs.

Afterwards, for the flowering stage, you’d switch to your high pressure sodium. This is like the middle of the summer season with crimsons and nice and hot for pushing big bud development.

However, perhaps the easiest lighting solution for the veg stage is an LED grow light. It's trendy because it hardly draws any type of power and it generates only a small amount of heat. Plus with preferred models, you can switch the color spectrum of the light output from blue to red when you go to the flowering stage.

Whatever light source you choose, you’ll need a dependable timer. Don’t skimp here since the success of your grow depends upon this little device. You certainly can’t be manually flipping the switch every day because it will be nearly impossible not to mess up. For the veg cycle, set you timer for an 18-hour light cycle with 6 hours of darkness. Later you’ll be switching that to a 12-hour cycle for the flowering stage.

When setting the timer, think about your own day and when you’ll be doing your daily check on your plants. Just make sure the lights are on to accommodate your schedule.

For your temperature, keep things around 22 to 23 degrees during the day and 21 to 22 degrees at night with relative humidity from 60% to 70%.


What nutrients are your plants going to require throughout the vegetative state? Since you’re already using an organic super soil, the answer is not much if anything.

If your soil ever needs a pick-me-up, add some compost tea. You prepare compost tea by steeping compost with an aerator to promote the growth of beneficial bacteria and fungi.

Your goal is to promote a healthy and balanced ecological community in your soil, which is very important for your plants' development. Simply stay clear of pre-mixed soil with synthetic fertilizer in it.

Soil pH

You shouldn’t need any pH adjustments with your organic soil. The microorganisms breaking down the organic matter will make the nutrients more available to the roots. pH becomes an issue with standard potting soil where root uptake of nutrients depends upon the pH of the soil.

That’s why you may have heard of the need to keep soil pH between 6.0 and 7.0. But with organic super soil, this issue should go away. You can alway check your soil pH just for peace of mind, but if your plants look healthy, don’t mess with it..

For some background to the uninitiated, pH is measured on a scale of 0 to 14 where low is acidic and high is alkaline; 7 is neutral and right in the middle.


Do not over water your plants and also certainly don't under water your plants. You can use a moisture probe to help monitor things, but really just use it as an indicator of whether you should simply lift the pot up to see how heavy it is. A light pot means it needs water. Don’t depend on the probe too much because they sometimes don’t work that great.

Another quick check to see whether a pot deserves lifting is the knuckle test. Stick a finger down the soil and if it’s dry at the second knuckle, about two inches down, lift the pot to see how heavy it is.

After your plants have reached a foot or two, and depending upon the strain you’re growing, you'll want to start pinching your plants to grow a little bushier and get more buds. There’s a specific way for doing this, one is called topping and one is called FIM. Check this article here for more detail. Your yield will suffer if you don’t pinch.


In a nutshell, for the veg growth stage, go with a five gallon pot and an organic super soil. Choose either a ceramic metal halide grow light or an LED grow light. Set your light timer to 18 hours of light and 6 hours of darkness. Plan the light cycle so the lights are on for your daily check. Avoid over-watering your plants. Train your plant for maximum bud production by pinching the right spots during the veg stage. Do everything right and you’ll be rewarded with healthy, bushy plants ready to grow lots of buds.

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