Identifying When To Harvest Marijuana

Rambo December 12, 2011 2

It can be a bit daunting for beginners to identify the proper time to harvest marijuana plants. The anticipation of enjoying the fruits of your labor, and fears of losing everything to thieves, has led to many gardens being harvested before the buds were fully mature. Not only will harvesting immature buds mean a less developed taste and smell, it also means lower weight and much lower concentrations of cannabinoids like THC in the buds resin.

Trichomes on Cannabis, rich in cannabinoids.

To determine your marijuana is ready to harvest you’ll need to look very closely. The telltale signs are located in the plants trichomes.  To the naked eye, trichomes look like little white crystals covering the plants buds, leaves, and sometimes even stalks. Once examined under magnification you will see that trichomes are actually translucent resin glands protruding from the plant. There are actually three kinds of resin glands on marijuana plants, but capitate-stalked glands are probably the only ones you can see clearly with a magnifying glass or jewelers loop.

Trichomes are present throughout the plants growth cycles but rapidly increase as marijuana begins to flower.  As the plant reaches full maturity the trichomes increase in size and cannabinoid density and their appearance changes from clear to either light amber or a cloudy white. You will know it’s time to harvest when the majority of the larger capitate-stalked trichomes have begun to change color.

Unfortunately there is a second way of knowing when it’s time to harvest. An outbreak of our nemesis Botrytis (Gray Mold) can end a growing season before your plants have fully matured and are ready to harvest. Botrytis spores are everywhere and just a fact of life marijuana growers need to learn to deal with. Preventing Botrytis outbreaks can be a multi pronged defense, but once you find botrytis in your buds there is only one thing to do, harvest, and act fast.

Botrytis usually strikes when cannabis flowers have become fully developed but this doesn’t mean it can’t hit your garden weeks before the ideal harvest date.  Botrytis can be hard to spot because it begins to grow on the inside of the buds and works its way from the stem to the outside of the bud.  The mold spreads very quickly and turns everything in its way to mush. Usually the first sign of botrytis appears at the top of main kolas giving them a grayish wilted look. You can also look for leaves protruding from the kola beginning to shrivel or die.

Once Botrytis has been spotted in your garden the infected buds must be harvested immediately. The infected area should be cut out of the bud as well as the areas touching the infected area. As soon as infected buds have been removed; the rest of the larger buds should be carefully checked every day. If the outbreak botrytis is widespread, it’s time to harvest. Start with the largest buds as they will become infested first. Once the larger buds are harvested it’s really a judgment call to either take the smaller buds or to wait and see if you can get further maturation from them without huge losses from infestation. 

Botrytis will not necessarily stop destroying your marijuana just because you’ve harvested. In addition to removing all the infected areas, you must completely dry the buds as quickly as possible and keep close tabs on them afterwards. While it isn’t likely if your marijuana is dried properly, botrytis can continue to grow even once the buds are dried, cured, trimmed and stored away in air tight bags.

When and how you harvest is partly dependent on the cooperation of nature and a good deal of luck. While nature can be controlled to some degree by advanced methods like growing marijuana indoors or hydroponics, there remains a number of factors that marijuana growers can never completely control. These factors will have a great impact on how and when you harvest your marijuana, and the quality of the end product.

VN:F [1.9.22_1171]
Rating: 3.3/5 (29 votes cast)

Identifying When To Harvest Marijuana, 3.3 out of 5 based on 29 ratings



  1. 45YearToker August 29, 2012 at 4:31 pm -

    While I would generally agree with Rambo, that once mold starts, it’s time to harvest, there can be exceptions. This winter I grew in my greenhouse. Flowering took place in March & April. When I was down to just 3 plants that were of a later maturing variety, I spotted botrytis in a cola. I immediately removed the infected bud & those in contact with it. Over the course of the last month of flowering and ripening, I found botrytis on 6 more occasions, and on 2 of the 3 plants. By immediately removing the infected buds, and those in direct contact with them, from the colas, I was able to prevent an outright plague, got the plants to maturity with only about 3/4 of an ounce lost, harvested over 3 Lbs & have been smoking and enjoying them since May. In a situation like this, with only a few plants, and the time to thoroughly check them daily, you maybe able to still get them to maturity without harvesting everything at the first awareness of botrytis. It’s a judgment call, for sure, but I was successful, and I believe that with diligence, anyone can be.

  2. shadowman March 16, 2014 at 10:02 am -

    Sounds logical to me, the smaller number of plants the easier it would be to stay on top of things. I’ll be growing for personal use and will keep that in mind.
    Thanks for your input, I’m a rookie and need all the advice I can get.