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Day-length illustration with picture of the sun.

When to Harvest your Hemp Crop

Hemp is known to be a short day photoperiodic plant. In other words, hemp responds to the decrease in day length (number of hours of sunlight in a day) by initiating flowers. Up until the summer solstice (Usually 3rd week of June), the days increase in length. After the summer solstice, the day length begins to decrease, triggering hemp to begin the reproductive cycle by initiating flowering. For this reason, it is important that you know the expected day lengths throughout the season in your location. This will help you plan your planting schedule. Now let’s talk about when to harvest your crop.

graph showing the daylight hours over the course of a year.  day length is an important factor in determining when to plant a hemp crop

For many growers, both novice and seasoned, google is one of the first places to look for the answer to this question. If you have done this and left still scratching your head without a clear cut answer, you are not alone. There is a lot of information out there that is generalized. However, there are some important aspects to this question that are fundamental to ensure that as a grower you are harvesting your crop at the right time.

1. Where are you growing?

You may have found on google that you should harvest in September or October. Well, that is vague. Last time we checked there were 4 weeks in September and October, giving us a range of 8 weeks where things can go wrong if not on top of the harvest information.

Where you are growing is very important to understand the harvest schedule of your crop. If you are growing in Connecticut, you would expect it to get colder there sooner than if you are growing in North Carolina. In Connecticut you could have your first heavy snowfall by October, so understanding your climate where you are growing is vital to a successful harvest.

2. What variety are you growing?

This may be the most important aspect. What If we told you that it doesn’t matter what variety you grow, they all get harvested at the same time? Well if that was true then you need to wake yourself up because you are dreaming. Each variety out there varies in their genetics, making harvest time difficult to predict. There are some varieties that are more sensitive to photoperiodic change. Some may flower earlier, some may flower later. As a grower you want a uniform crop at harvest.

THC content is an import factor to watch when determining when to harvest. Every variety is different in the amount of THC it produces and stress and other environmental factors can increase THC production. It is import to test your crop for THC content starting around 4 weeks after the initiation of the flowering cycle. Testing should be performed weekly to ensure THC levels are below the legal limit of 0.3%. You may have to harvest your crop early if the amount of THC is approaching 0.3%.

Knowing the varieties you are working with is fundamental to understanding the correct time to harvest your crop. The best way to do this is to do an in depth research of the varieties you select and talk to your supplier. A quality supplier should know how their varieties perform and should have a good idea of when flowering initiates and the time it takes for those flowers to reach maturity.

To help you better prepare for the up and coming season, be sure to research your growing climate and the varieties you plan to grow. Be proactive and ask your supplier. If they are unsure, then it may be time to find a new supplier.