If the leaves on your marijuana plant yellow colors all kinds of things are going one. Here are some possible causes in a row.

If you grow and bloom nutrients, make food as whether growth can be used throughout the life cycle of the plant. The growth in food may contain substances that are not only good in the growth but also for the flower!Yellow leaves can indicate a nutritional deficiency, so this might arise because you are in the floweringstops your growth diet.

If the plant at the end of its flowering period, then you have yellow leaves mainly at the bottom of the cannabis plant, this is very normal. Let the leaves sit until it falls off itself, directly below cleanup otherwise you suffer from insects or fungi.

What you should first check with leaf problems

1. Ventilation - Provide adequate fresh air for your plants
2. Temperature and humidity - Provide the right temperature and humidity 
3. Lighting - Provide the right amount of light and use it the right way
4. Pests - Use a magnifying glass to the bottom of the leaves to check for pests. If you are suspicious-looking spots, eggs or insects will see the heading insects and vermin. 
5. Stains or traces - Are there any stains or marks are visible but no form of life then you would weed plant may experience a yeast infection. Take a sheet and take it to a specialist who can tell you what you should do to prevent spreading. There are special antifungal agents, make sure you're not using it right before harvest, it is possible that remnants of these funds you get when you smoke weed. 
6. Color of the leaves - Do the leaves of your plants a deep green color of the leaf tips are a little burned then the chances are you too much nutrient. When feeding on the leaves can also be yellow. Exhibit your leaves or slight yellow discoloration then they have a shortage of nutrients, this is the right time to add fertilizer. In the beginning compost contains enough materials to the plant to grow tasty. At a later stage may require that you have extra food during application.

Possible causes of yellow leaves on your weed plant

Wrong food or too much food

Measure the EC value of your land. Use distilled or demineralized water because it does not add salt to your soil test. If the EC is too high then you do well to diet for a while no more to give. Rinsing earth is no possibility. Due to wet ground you more problems. 

How much food should have a marijuana plant?

How much food should have your weed plant is entirely dependent on the brand growth medium. The best thing is a complete nutritional buying from a manufacturer. If you used the breeding scheme of the brand is always good. 

Do the leaves of your plants a deep green color of the leaf tips are a little burned then the chances are you too much nutrient. When feeding on the leaves can also be yellow. Exhibit your leaves or slight yellow discoloration then they have a shortage of nutrients, this is the right time to add fertilizer. In the beginning compost contains enough materials to the plant to grow tasty. At a later stage may require that you have extra food during application.

Large leaf turns yellow, small leaves remain green

- This is probably due to a shortage of nitrogen. What can you do? Increase the amount of nitrogen in the nutrient solution and keep an eye on what happens. If the marijuana plants the coming days are darker in color reduce the amount of nitrogen.

Mature leaf curls are dark or purplish in color

- Probably there is a shortage of phosphate. Increase the amount of phosphate. 

Adult leaf turns yellow and mottled with dark gray borders

- Probably your plants a potassium deficiency.

Young shoots die, discolored veins of leaves yellow or white

- This is probably a lack of calcium.

From the bottom leaves are yellow, veins remain green and edges curl

- This indicates that a deficiency of magnesium.

Chlorosis of upper leaves but with green veins

- Chances are that your weed plant is short of iron.

Deformed and ill-formed leaves

- This is usually a shortage of zinc.

It may be that your weed plant just gets too much power.

• If the plant to grow too close to the lamp.

The water

• The water that does not give you the proper pH (acidity).
• Yellow leaves on a cannabis plant also get too much water.
• A low humidity. Plants remain behind in growth, leaves are dull and fade to purple stems because the leaves close to reduce evaporation.
• For wet roots so that oxygen can be problematic, and an iron shortage. The cannabis plant is slowly becoming more yellow, starting from the fresh leaves.

Temperature

• For low temperature in the loft so the blade matte (not shiny) is the steal harden, growth remains and leaf and stem to purple discoloration.
• Too high a temperature for the leaves to curl and pinking and thus a lower density peaks get, they feel spongy

Poisoning

• CO2 poisoning, such as a boiler in the same room as the plants are grown. The cannabis plant than to fade lighter yellow.
• Poisoning of the plants by sucking dirty air from another space such as an adjacent garage or a poorly ventilated basement.

p.s You cannabis plant can also get yellow leaves of stress far repotting or moving much.