7 Ways for an Indoor Grower to Check Before Harvesting Cannabis Plants

How Do the Trichomes Look Up Close?

With the help of a magnification tool designed for cannabis growers, you will be able to set your trichomes up close. Once you can see the trichomes, you will be able to see how small or large they are, the development and if the trichome head is clear, cloudy or closer to amber. 

For your reference, when trichomes are clear, this will indicate that they are not quite ready as yet, and will not be as potent when harvested at this stage. Milky or cloudy trichomes will be the optimal point when to harvest your plants, as they will have a good amount of potency and the best flavour. 

If the trichomes are mostly cloudy with a 25% ratio of amber coloured, then your plants will be the most potent in terms of physical effect, and are a sign that they may be 5–7 days past the ideal harvest window. That being said, many growers prefer to harvest and smoke buds that display a high percentage of amber coloured trichomes due to the potency and smoking experience they provide. 

The Amount of Resin on the Buds and Leaves

The more trichomes that are present on the buds and surrounding leaves, the more often be a sign of the quality of the genetics being grown and how close you are to harvesting. Cannabis plants during the final 3 weeks of flowering will start to produce a prolific number of trichomes and harvesting too early will result in a loss of terpenes, cannabinoids, and essential oils.

You should also consider that cannabis plants can produce different phenotypes, so not all plants will be as frosty and resinous as others, or will be ready to harvest at the same time. You should leave your plants to produce as much resin as possible during the final weeks, and then, with the help of a magnification tool as mentioned above, judge based on trichome maturity.

The Terpene Profile and Aroma

Within the trichomes, will be all the essential oils, terpenes, and cannabinoids that make your cannabis plant unique and allow it to fully express itself. I have found that the more aromatic and sticky the buds are to smell and touch, the way to judge if you are close to harvesting, however, this only applies when the buds are as chunky and dense as can be. 

You should avoid harvesting cannabis plants that have a fresh chlorophyll smell to them, as this will be an indication that the plants are still fresh and need more time and a chance to develop, and if harvested early will not possess much flavour or aroma.

How Swollen Are the Bracts and Calyxes?

Cannabis buds are made up of bracts and calyx, and the more developed these are, the more an indication of how dense the buds are becoming. Photoperiod cannabis plants will begin to fatten up during week 6-7, and if you are growing autoflowering cannabis plants, then buds will begin to swell and fatten up between week 5 to 7 according to Auto-Seeds.

Flowering boosters will often promote stacked buds that have a hard to squeeze and dense profile. It is best to check how swollen and resinous your buds are, combined with the number of brown or orange pistils present, as a sign of the harvest window. 

The Fade During the Flushing Stage

I always flush my plants with plain water for 2 weeks during the final stage of the flowering period. As cannabis plants are starved of nutrients during the flush, they will use up all of their internal reserves of nitrogen, phosphorus, and potassium. During this time, the fan leaves will begin to fade. This is the point when plants can exhibit a wide variety of colours from yellow, red, pink, and purple hues, giving them an exotic appearance. 

One way to know you are close to the final harvest date and optimal harvest window is when your crops have faded and become multicoloured. The fan leaves will also become brittle to touch, and there should be no signs of green if the flush has been performed correctly. Not every grower will flush for 14 days, and some even argue if flushing cannabis is necessary and argue the plants need the nutrients during the final stages.

Consider Different Phenotypes

A phenotype can mean that even though you are growing the same strain, some plants may flower sooner than others. So when you are growing many plants, check each one individually instead of harvesting them all based on the flowering time alone. Pure sativa genetics and sativa hybrids can often produce phenotypes that take up to 7-10 more, so try your best to isolate each one and check how swollen the bracts and calyx are, as well as trichome maturity.

An example of a phenotype that may take longer to flower than other phenotypes would be a Skywalker Haze plant. If you grow out 10 plants, then there is a good chance that 3–4 plants will lean on the Haze side, so compared to the faster flowering Skywalker phenotypes, you may be required to leave them in for 7–10 days more. Harvesting the entire 10 plants based on flowering time may result in the Haze phenotypes not ripening as well as they could have with more time, and this will be noticeable when smoking.

The Number of White, Orange or Brown Pistils

In the old days, many old school growers would in-fact use the number of white to brown hairs as a way of determining if their plants were ready to chop. I find that an 80/20 percent ratio of brown or orange hairs to white hairs is the ideal time to harvest and represents peak ripeness, and often produces the best quality buds. Never harvest your plants when there is a high ratio of white pistils as this will mean the plants are several weeks off full maturity and will result in a loss of yield, potency and flavour. 

My Final Thoughts

There are many ways to identify if your plants need more time before harvesting, or at the perfect point. The best advice I can offer is to buy a magnification tool that is designed for growers, and get up close and personal with your plants. Doing so will allow you to have much more influence on what stage the trichomes are, and if you want to leave them longer for a much more potent and physical effect once dried and smoked.