FI found this on a thread around here somewhere.
It’s long BUT great info start to finish
As with most tricks of the trade, there is always a catch. And in this case it can be taken quite literally as well, because when checking your buds for ripeness you’ll want to “catch” any and all clues that can signal maturation—a few weeks before harvest time. Having a “harvest heads-up” can be extremely beneficial for growers, not only to prep equipment and rooms for drying and curing, but also to prep the plants for taste and smooth smoking.
If a grower can consistently examine trichomes and keep accurate time records from the start of the flowering photoperiod (12/12 light cycle), then it should be no problem for the grower to begin flushing out the grow medium in preparation for the harvest.
The Two-Step Flush
The last two weeks of flowering should be spent getting rid of any built-up nutrients in the growing medium, a process called leaching, or flushing. By removing all access to nutrients, the plant begins to consume its stored food reserves. These reserves are nasty compounds that we don’t want in our smoke, such as sugars, starches and various other elements. Harvesting plants that still have these undesirable elements present will only result in a harsh smoke and terrible burnability.
Flushing should begin about 14 days before harvest by stopping all nutrients and using only pure water to feed the plants. By providing no nutrients, you force the plant to rely only on what is left in the growing medium to feed on. The actual act of flushing is achieved by over-irrigating the medium until the nutrients inside are dissolved and washed out the bottom of the container. The best way to do this is with a two-step flush technique. (The process is an easy one.)
First, flood the grow medium with a heavy dose of water and wait a few minutes to allow all of the salts (nutrient buildup) to break down. Then add more water to chase out the first dose. By waiting a few minutes after adding the first dose of water, you’re allowing enough time for the water to dissolve the salts. As salts decompose, they can be effectively flushed out by the second dose. Traditional leaching usually employs only the first flush of water, which isn’t always adequate for complete dissolution.
A few days after flushing, you should notice signs of nitrogen deficiency. The leaves will go from dark to light green, eventually turning completely yellow. Another sign is a reddening of the leaf stems, starting at the center of the leaf where the blades come together.
Test your flush by snapping off a leaf and tasting the juice that flows from the stem. If the taste is bitter, there’s still plenty of food in the plant’s system. When the juices are clean and taste like pure water, the plant is clean enough for harvest. The bitterness is from nutrients and other chemicals that you definitely do not want in your smoke.
Dry Air = More Resin
One final flush should occur a day or two before harvesting, with the final 24 hours of the garden’s life being spent in relative dryness. This last deluge should be done with fresh water and can be a single or a two-step flush, depending on how much fertilizer was applied previous to the final two weeks of flowering. This will be the final watering your plants ever get. In doing this, you help ensure that the plants will begin to slowly dehydrate as you approach harvest, which in turn will aid the plants in their final hours of resin production.
Some gardeners even like to allow their medium to go bone-dry before harvesting. The idea is that resin production seems to skyrocket if the medium is allowed to dry before harvesting, but this isn’t due to dry medium – it’s due to dry air.
When the relative humidity in the garden is low, your resin production will increase. This is a natural response cannabis has to dry air, an attempt to protect itself from hot, dry conditions. Marijuana resin actually has one of the highest UV-resistance ratings in the plant kingdom. The resin reflects light, preventing the buds from getting sunburn. (This is also why it’s so easy for helicopters to spot marijuana from the sky; it glows when seen through UV-sensitive equipment.)
Lowering the humidity in the room on that last night before harvest morning will ensure increased resin production, without having to let the medium go bone-dry first. Additionally, some growers like to subject their gardens to prolonged dark periods of up to 24 hours just before cutting, claiming they notice spikes in resin production. This is all right as the low humidity will cut down on light uptake anyway, plus it helps to make sure liquid foods within the plants drain down to the root zone.
Harvest & Manicure
When the big day arrives it is best to start early, before the light period begins in the growroom. If the grow lamps turn on, it’s okay to cut them completely and work by standard room lighting. Begin by cutting the entire plant away from the root ball. If the plants are too large to harvest with one cut at the bottom, start by cutting the larger, heavier branches first. Remember to leave one or two larger stems connected to the branches you are cutting off. These stems will form nice “Vs” on the branches for easy hang drying.
Most indoor growers begin taking off the large fan leaves about a week before actual harvest. This is a good idea, especially once these leaves begin paling from green to yellow in color. Continue your harvest by taking off all leaves not associated with the buds and then move on to trimming off the smaller sugar leaves. Look for leaves with little resin coverage first and then move into the interior of the nuggets. It’s easier to remove leaves within the buds once they have dried out a bit, but that adds extra time and a second round of manicuring. By turning buds over and getting to the underside of smaller sugar leaves, it becomes easier to snip away at the stem and remove the entire leaf. Many growers like to only trim off leaf edges that come out of buds, leaving an aesthetic shape to the bud with the heavily resinated portion of the sugar leaves still intact within the buds.
Once the plants are cut, trimmed and manicured to perfection, it is best to hang branches upside down on strings strung across open spaces to get maximum air flow over your buds. Keeping buds on the branches does slow the drying, as the branches do retain some water however, this is the easiest way to completely surround buds with dry air without using drying chambers or machines.
Drying for Taste and Burn-ability
Now that you’ve harvested and are ready to dry and cure, you will want to preserve as much of the vibrant color and taste of your herb as possible. Buds should hang dry for five to seven days at the ideal temperature of about 70ºF with 50 percent humidity. You want to get most of the water out of the buds in those first days and then slow the process down for another week or so during the curing process.
Remember that a plant is not dead upon cutting—it is still very much alive. A plant is effectively dead when the water pressure inside is too low to continue vascular movement. In other words, when the waterworks stop, the plant is dead. The goal here is to dry the plant as evenly as possible and at a nice slow pace. When buds are rapidly dried, the plant tissue can trap in unwanted starches and nitrates which cause buds to burn unevenly and with an awful taste.
At four to five days into the dry, the tips of some buds might be dry enough to pluck off and sample. After the buds have gone through their full cycle of drying, we want to slow the whole thing down and draw the rest of the moisture out very gradually. This is the curing process.
What’s the Cure?
If your herb is harvested correctly, there is very little need for long cures. Long cures are needed to make harsh herb smoke smoother. If you start out with smooth, clean herb, there’s less need for long cures. Most buds should be cured and ready to smoke in less than two weeks after the drying period. Expert growers who harvest properly can complete curing in five or six days, but a good average can easily range from 10 to 14 days.
Inexperienced growers often tend to get impatient and only cure for a few days, but this can be a costly mistake when it comes to potency. Allowing the buds to cure evenly, which means drying at a slower rate, removes moisture within the buds so that all the THC can be converted in its psychoactive form.
The curing process evens out the moisture levels in the herb. You want the same amount of moisture in the center of the buds as you do on the outside of the buds until they are almost totally devoid of fluids. Completely drying the herb too fast can trap moisture in the middle and not allow for a proper cure.
For the curing process, you want to put the half-dried buds into air-tight containers. Inside the container, the buds will become evenly moist, inside and out, as they begin to “sweat.” You can check to see if your buds are sweating and releasing moisture by gently squeezing them between your fingers to see if they feel damper than they did a few hours before sealing them up. Glass jars with rubber seals and lockdown lids are the best option for curing, but for large amounts of harvested buds, you’ll need something much bigger. Tight-sealing rubber or plastic bins are the best option for large quantities of buds but many growers feel these containers impart a plastic-type taste onto the buds. This can be offset by adding a small slice of lemon or orange peel to the bins toward the end of your cure.
Once the buds are again evenly moist, open the containers to let the moist air exchange with fresh air. Air exchanges are essential to the curing process. Not only do they prevent condensation from forming in your curing bins, but the fresh air is drier than the air you just allowed to escape from the container. The moisture still trapped in the herb will again slowly escape and moisten the new, fresh air. Open the container several times a day to exchange the moistened air with fresh air to slowly draw out the moisture in the buds. Eventually (again, one to two weeks) the moisture level in the herb will be at the right level to stash away and, of course, smoke!
What Time of Day to Harvest?
Timing the harvest is Paramount to the final quality. Harvest your precious buds in the dark, just before the lights normally come on. If possible, do not allow the plants to see direct light as long as their roots are attached. Direct light on a plant will draw up stored starches and sugars from the root system.
During the nighttime hours, our ladies are busy storing food down in their root system that they made during the daylight hours. During “lights out,” starches and sugars produced by photosynthesis during the day drain downward to the roots. Knowing this, it is easy to figure out that you want to cut your plants away from the roots before the lights come on, when food moves back upward into the buds.
Outdoor herb is often harvested during the daytime hours and the result is a harsh, difficult burn and an extra long cure. The starches and sugars present in daytime-harvested herb act like fire retardants—not the effect we’re looking for. In addition to tasting and burning bad, these fire retardants also change the chemical make up of the smoke you’re ingesting. This means that the THC, cannabinol, cannabidoil and other active cannabinoids can’t burn at the perfect temperature to get you properly high because they haven’t properly converted to their psychoactive forms.
Facts on Drying & Curing
• During the drying of marijuana buds, THC is converted from an acidic, non-psychoactive chemical into a neutrally based, psychoactive form that gets you high. This is why fresh marijuana is generally weaker than properly dried and cured buds.
• Marijuana will lose approximately 75 percent of its weight during drying due to water evaporating from plant matter.
•Buds dried too fast will be frail and may start to crumble. Keep humidity between 45 and 55 percent in your drying room to prevent this and to help keep aroma and flavor locked in.
•Buds are done drying and ready for curing when stems snap when bent rather than just folding over.
Good luck with your buds