Learn more about how harvesting at different times changes the potency/effects. If you let the flush go this long, where buds are getting crispy and brown without any sign of green, it means the actual potency of your bud is starting to degrade. This bud needs to be harvested immediately so you don't lose further potency! You've been working so hard, and now you are almost at the end of your journey! You've done everything you could to ensure the smoothest buds, so now it's time to enjoy the fruits of your labor!
The biggest problem with flushing, especially for new growers, is to start the flush too early. New growers commonly think their plant is just a week or two from harvest, when truthfully it’s 4 weeks or more away from the optimal harvest time. Breeders often understate the length of the flowering stage for strains, giving the timeline for the absolute earliest harvest, so it's generally a good idea to add an extra two weeks (minimum) to their recommended time for a more realistic estimate of the optimum time to harvest. When you flush a cannabis plant too early, you’re stunting its growth because buds aren’t getting enough nutrients to develop properly. Without being given the right amount of nutrients during the most crucial parts of the flowering stage, the potency, quality and weight of your buds can also be lower. Growth is stunted during the most important parts of the flowering stage, and yields are reduced.
Potency may be lower because buds didn’t have the nutrients needed to develop THC properly, and if buds are also harvested early it reduces the potency even further! The appearance of buds can be affected, as a plant left too long without nutrients starts developing nutrient deficiencies that can spread to the sugar leaves on your buds, causing unsightly yellow leaves. Although this doesn't negatively affect how the bud smokes, taking care of your sugar leaves until harvest is very important to get the best-looking buds (this is also another reason why it’s important to avoid too much nutrient burn) Flushing too early or too long can hurt the looks of your buds because it can cause the sugar leaves start turning yellow! All the nutrients were used up in the plant, including the ones in the sugar leaves, causing unsightly yellowing on the buds/sugar leaves that’s almost impossible to trim off. Allowing this to happen gives you buds covered with little yellow parts where the base of the leaves were, before they got trimmed. Example – After the bud was trimmed and dried, there are still yellow spots from the base of each sugar leaf that turned yellow, making buds look lower quality than they are! This example shows a normal bud where sugar leaves remained green at harvest, no yellow spots. The bud which didn’t have yellowing has an overall higher quality appearance – more evidence that it’s so important to time your flush right! I’ve seen so many growers finish their two-week flush, and realize their plant still has several weeks to go after the flush is over. Do they continue flushing, do they start using nutrients again, or do they just harvest the plant early? It’s hard to say which way is best in a situation like that. So when it comes to flushing, I personally believe in waiting to flush until the harvest window has just opened . What that means is I won’t start flushing until the buds can already be harvested now, even if it’s a bit too early for my preference. Once the buds have hit the very beginning of the harvest window (trichomes are at least half-clear, half cloudy – learn more about trichomes and when to harvest), they still usually have 3+ weeks before the plant reaches the end of the harvest window. I personally like to harvest plants a little on the later side, because THC levels are higher, buds are bigger, and effects tend to be more relaxing and not “racing”. So starting the flush at the very beginning of the harvest window allows you to time your harvest perfectly for a 2-week flush. You won’t be able to flush too early if you follow this principle! If your plant still looks like it’s a few weeks away from harvest, wait! You never know how the plant is going to mature, and you can’t be sure that harvest time is close, until the harvest window has actually opened. Another common problem growers have is they stop maintaining pH when they start the flush. Even during the flush it’s important to maintain pH at the roots to make sure your plant can properly use the nutrients available. It can help prevent yellowing and spots on the leaves during the flush; when the pH is too high or too low at the plant roots, it makes certain nutrients unavailable to the plant and increases the chance of seeing nutrient deficiencies.
The plant also tends to absorb more aluminum and salts out of the water when the pH isn't in the correct range. Maintaining pH throughout the flush will help prevent deficiencies and unwanted salt absorption, while still allowing your plant to use up its extra reserves of nutrients in the buds! It’s generally recommended to flush plants for a few days to 2 weeks. Unless you're growing in amended super soil, flushing for longer than 2 weeks without nutrients is likely to stunt growth of the buds, which we don’t want in the flowering stage!
Many growers agree that a few days to 2 weeks is a good amount of time to flush. Soil Growers Flush 1-2+ Weeks – Soil growers should flush the longest, from 1-2 weeks. This is because there is still some amount of nutrients left in the soil. For super soil growers who haven't used any nutrients from seed to harvest, you don't have to worry about flushing because you've been giving plain water from the beginning.