I've said it for years now. The best smoke comes from a FULLY RIPENED healthy plant that is dried slowly.
If its an couch lock high you want grow a plant known for that and grow it until its FULLY RIPENED. If you want a uplifting high grow a plant known for that until its FULLY RIPENED.
Harvesting plants early reduces terpenes, high duration, level of effects and yields. Harvesting a plant that is FULLY RIPENED will lengthen the high, increase whatever effects that strain has, and maximize the yield and quality of the bud.
I'm sorry I don't have scientific studies to prove this, but I've personally grown thousands of plants that I"ve shared with friends and family over the last 16 years I've been growing. As well as smoked buds that friends and family have grown, and that have been dispensary purchased. So my data collection has been extensive albeit anecdotal.
I believe the whole wait for 30% amber or which ever harvest suggestion you might pick from a "grow guide" or off a site all stem from the goal of trying to get people to reach the maximum potential. I'll also add that any site or book that tells you that you can harvest a plant with 40% white stigma(pistils) is just plain wrong and anything else they say should be questioned heavily. In case you haven't seen it, here is the harvest guide that I share with new growers that are trying to actually understand the plants physiology.
The signs of ripeness are pretty standard for cannabis plants.
First a few of the pistils begin turning color and start receding. Your plant is just starting to ripen. Depending on the strain you could still have two months to go. We're just starting this journey.
Two to four weeks later you'll notice that most of the pistils(>80%) have now changed color and curled back into the bud. It's frosty, way bigger than it was a few weeks ago(aren't you glad you waited), and smells dank! It's time, right? Not a chance killer. Patience is a virtue.
Over the next 2-3 weeks it doesn't look much different, maybe a little more swelling in the calyxes, and the rest of the pistils change over, but the stems are starting to bend under the weight of the buds. These ladies are putting on weight internally by adding density and now the buds are doing their final ripening.
Now you begin looking at trichomes, on the calyx, not the leaves, and harvest according to your preference. When looking at trichomes it’s essential to look at them from the side. The bulbous heads can magnify the opaque stalk under it. Looking from the side allows you to more accurately see the condition of the resin in the trichome head.
There is still no rush to harvest, the window just opened, and you have several weeks before you MIGHT start having to think about it possibly beginning to get too ripe. It takes WEEKS for plants to mature not days.
It is very easy to harvest a plant to early. It is very hard to harvest a plant to late. I’ve never seen someone accidentally wait too long.