Harvesting, Drying and Curing Marijuana
OK. You’ve grown your big buds from a tiny seedling to a mature cannabis plant.
There are lots of signs that your plant is approaching maturity and you are ready to harvest, dry and cure your marijuana. As the flowers grow they will merge together into heavy kolas. You will notice each ovary swell and tiny crystals will be visible around the flowers. The flowers will become sticky to the touch and the aroma may become pungent. As the flowers swell the white pistils begin to darken, going from white to a reddish brown.
During this time some of the larger fan leaves may begin to yellow and wilt. This is a perfectly natural part of the grow stage. It is OK to remove these leaves and allow more light to the lower parts of the plant.
When to Harvest Marijuana Plants
One of the topics that we get lots of questions about is when to harvest your plant. As with most aspects of growing your own weed, the answer is not black and white.
The last week before harvest can be a testing time. Seed Banks will give you a flowering time for the strain that you buy. This is never exact though; there are too many variations in different growing conditions to be able to put an exact length of time on it. Add to that the variation in phenotypes inherent in most cannabis strains, and the varying preferences of individual marijuana users, and you have quite a wide window of opportunity.
Most growers use the color of the trichomes to help them decide exactly when to harvest. The trichomes are the tiny structures on the flower (and trim leaves) of your plant that produce the resin where all that THC goodness is. Do not confuse them with the pistils which are the long hairs protruding from the flower.
To get a proper look at the trichomes you will need some sort of magnifier. Simple 20X jeweller’s magnifying glasses, bought on ebay or loupes are easily and cheaply available. Not only do they allow you to inspect the trichomes properly, they also open up an amazing world of imagery and an aspect of your plant that can be fascinating to look at.
So what exactly is it that you are looking for?
As your plant matures the trichomes will go though three observable changes;
- Trichomes swell and heads flatten or ‘mushroom’
- Trichomes change from clear to milky or clouded
- Trichomes begin to turn amber or brown
The image below shows fully formed trichomes going from clear, to milky, to amber.
What’s happening with these changes is that your plant is converting its nutrient energy to THC, and then, as the trichomes darken, converting that to CBD.
If you observe the trichomes carefully you can choose the moment of harvest to meet your own particular preferences.
Do you prefer a heavy physical stone, or a lighter head stone?
As a general rule, the longer you leave you plant, the heavier the stone.
For most growers harvesting when the trichomes are all clear is too early. Marijuana with clear trichomes will still get you high, but the effects may be light.
Some growers like to take their plants when the trichomes are all milky. This will give you a good hit, but without being too heavy.
Most growers like to harvest when a given percentage of trichomes have turned amber; anywhere from just a couple of individual amber trichomes to around 80% amber. The stone that you can expect just gets heavier and more physical the further you go along this scale.
Of course, as always, the strain that you choose can have some influence on this. As a general rule you could say that:
- Indica dominant strains have a heavier stone by their nature. For indicas there may be no need to wait for amber as partially cloudy trichomes may still give you a body stone.
- Sativa dominant strains are by their nature more cerebral and less physical. To get a good bake from a long flowering sativa you may need to wait until at least 25% or more of the trichomes have turned amber.
You will need to learn from your own experience of the results you get from your set up. The rule of thumb remains true though – the longer you leave it, the more narcotic the effects.
How to Harvest Marijuana
So, having decided when it’s the right time to harvest, how do you go about it?
Well, first we need to talk about flushing.
Many growers flush at intervals throughout their grow. The reason for this is to clear out the build up of nutrients within the system.
When you feed your plants they do not use all of the nutrients that you give them immediately. Some are stored until needed. However, as you keep feeding your plant the same nutrient mix there can be a build up of certain nutrients or minerals. Because these nutrients often work in tandem with each other you can sometimes get the situation where available nutrients are ‘locked out’ because of the absence of others.
Your plant may show deficiency symptoms but no matter how much you feed it, it is not able to assimilate that particular nutrient.
To help prevent this imbalance from getting out of control you can flush clean water though the system and clear out all nutrients, effectively cleaning the slate and starting again.
There are particular times when a flush may be appropriate for you.
- When you significantly change the nutrient regime (at the start of flowering for instance);
- When you are experiencing symptoms of nutrient lock out;
In the week or so leading up to harvest you may want to flush your plants if you are using non-organic nutrients. Especially in hydro set ups. Although this can be a controversial subject, most growers agree that flushing your plants before harvest removes chemical build up and improves flavor, not to mention avoiding the possible effects of inhaling those chemicals.
Marijuana that has not been correctly flushed can sometimes taste acrid and be harsh on the chest and throat, particularly on the exhale.
There are as many different opinions on flushing as there are marijuana growers and lots of people use different methods. Some never flush at all. Below are the basic methods for pre-harvest flushing in soil or hydro.
Flushing Marijuana in Soil
To flush marijuana grown in soil you need to run lots of clean water through the system. Many growers use rain water. You can add a flushing agent like Clearex if you prefer, although it is not necessary. pH your water to around 6.2 and run it through the container until you have around 80% – 90% run off. The actual amount will depend on how dry your soil is and how well it is drained, but you should be looking to put through about the same volume of water as the volume of your container.
Flushing Marijuana in Hydro Systems
To flush marijuana in hydro systems you should just run clean water through the system for the last few days. pH your water to about 5.8, although pH is not as critical at this stage as there are no nutrients to lock out.
After flushing, in both soil and hydro, you may experience leaf yellowing as the plant becomes deficient in nitrogen. This is normal and nothing to worry about.
Another thing you might want to consider just before harvesting is leaving your mature plants in total darkness for 36 hours. Although we can find no hard evidence to back this up, many growers swear that it gives their plants some extra potency by shocking the plant and forcing the very last of the its energy into creating resin.
So, assuming you have flushed correctly, it is time to get chopping.
Chopping Down Your Weed
Even if you have the space to chop and hang the whole plant, it is advisable to do this in sections. You should treat each branch and kola separately so that when you come to dry them they are hung separately without touching each other and there is plenty of air movement around them. This helps them dry more evenly, and lowers the chances of mold or other fungal infection.
It is sometimes easier to remove the larger fan leaves whilst the plant is still standing. The smaller leaves may be removed at this stage too. This will allow your plants to dry more quickly. However if you are not pushed for time then you should leave the smaller leaves on the plant. Drying time will be slower but, as the leaves protect the trichomes, the final smoke will be better. A slower dry helps retain weight, flavor and potency.
Using a sharp pair of secateurs or Fiskars cut each branch from the plant. Remove the large fan leaves if you have not already done so. Handle the branches very carefully; rough handling can cause the trichomes to drop off and that is something that we definitely do NOT want.
Now it is time to dry those lovely sticky buds.
How to Dry Marijuana
Hang each of your freshly harvested branches upside down in your drying area. Your drying area should be dark and have a good supply of clean fresh air. Good ventilation is key here. A fan will help, but try not to train it directly on your plants. What you want is air circulating, not blasting at them. Remember to provide lots of space around each individual branch.
Heat will cause your plants to dry faster, but as we explained above, this is not always better. An ambient room temperature should be sufficient. Inspect your plants regularly to see how they are doing and turn them around so that the airflow in the room gets a chance to get to all parts of the buds.
A lot of growers use custom made drying cabinets or boxes. This is basically an enclosed, controlled environment to dry your weed in. Some simple DIY could build you a box with hangers and a throughput of fresh air. You can also buy commercial weed drying cabinets such as this Supherb Drying Cabinet that is suitable for 24 plants.
Drying can take anything from a few days to a couple of weeks. The average time is somewhere around a week. You will know that your plants are dry when branches and stems crack rather than bend between your fingers.
This dried weed is smokeable now, but to get the best of the flavors and potency a final cure is necessary.
How to Cure Marijuana
Now is the time to trim your marijuana before the final cure. To give your buds their final manicure use a clean sharp pair of scissors to gently remove any remaining leaves that are shielding the buds. Part of this process is aesthetic and it is down to the individual to decide how neatly they want their buds trimmed. Wherever you are on the tidy bud spectrum, do not throw away the trimmings, the small trim leaves are often loaded with trichomes and if you don’t want to smoke them they make great edibles.
Separate the individual buds from the stems and store them in clean glass jars. Plastic tubs or bags will do, but we prefer glass.
For the first week or two that the buds are in the jars, open them up twice a day and allow them to ‘breathe’ for 15 minutes. This allows for a complete air exchange and removes any remaining moisture.
Your buds are now ready. Different strains may cure at different rates and you will often find that, if correctly stored, your weed gets better over time.
Good curing can make all the difference to your final smoke and is the finishing touch to all your hard work in the grow room.