One amazing thing that marijuana plants are capable of is vegetative regeneration even after the initial harvest. Some plants can give two or three different harvests in the same year. Second harvests usually happen about 6-8 weeks after the first. This is due to how much formation of the plant is already completed from the first time around. It takes just over half of the time for future harvests as it did for the initial harvest. You will want to remove only the top third of your marijuana plant when harvesting the first time. Cut off necessary branches very carefully and leave on as many of the fan leaves that are healthy as you can. Take the end flowers from the branches around the bottom third of your marijuana plant, leaving behind any of the tiny flowers that are covering the branches. This is where most of the regeneration will come from. You will have much more rapid regeneration if you can leave these buds on your marijuana plant. Give your marijuana plant a high-Nitrogen food as soon as you're done harvesting so it can keep its leaves intact. If it loses all of its leaves, your plant will die after harvesting. You can either regenerate your marijuana plants under the sunlight outside if the weather is warm, or you can bring your plants indoors so they have access to continuous light.
After 7-14 days, you will begin seeing signs of growth on your marijuana plants. The first growth will show up at the bottom of your plants, so look there first. Once you have some new vegetation established, your marijuana plants can return to the outdoors for another flowering phase. You can also keep this plant indoors if you plan to clone it. If you keep plants continually growing in all phases, you can end up getting a new harvest every 30 days. Just make sure you keep your plants healthy if choosing to go this route. Bringing plants in from the outside, or vice versa, can cause a lot of problems with pests infesting your entire crop, including your new clones or seeds. We recommend that you keep a separate area within your home to quarantine plants before they join up with the rest of your crop to ensure there is no cross contamination. Using the sun's light outside is a great alternative to bringing plants back and forth inside your home. Just try harvesting in June, following that up with the regeneration process and heavy Nitrogen foods. By the time fall rolls around, your plant will be immense and ready to begin flowering again on its own!
If you can increase the CO² levels within your growing location, you can nearly double the growth rate of your marijuana plants. When marijuana plants originated, the natural levels of CO² were much higher than they are now. Every marijuana plant requires CO² in order to perform photosynthesis, where the plant produces the necessary sugars for plant tissue growth. The more of these sugars can be made through photosynthesis, the quicker the marijuana plant can grow. It is difficult to safely, conveniently or inexpensively manufacture CO², plus tanks of CO² can get quite costly, so this has to be something only a serious and experienced marijuana grower tries. Unless you plan to use a greenhouse, growers who put their marijuana plants outdoors for flowering do not need to worry about using CO² on their plants. Sealed rooms are the only rooms that can even benefit from the use of CO² on marijuana plants. A room that isn't sealed won't have the CO² around long enough to affect the growth of the plant. Burning off natural gas will give off CO², but it will also give off CO and heat that will need to be vented away from the marijuana plants. Welding supply companies can also lease or sell you a CO² canister if you want to set up a regulated system for the long-term. Just tell them you have some old mig welder back at your house that you are going to be using to repair something like a trailer or a lawnmower. A small tank should be able to last you for about two months if being used within a small closet, assuming you release just a little at a time and have the growing room properly vented. You will also only want to release gas when your plants have light on them in order for the plant to be able to use it.
Most closets do not need a constant CO² flow whenever the lights are on and the fans are off, but bigger rooms could definitely benefit from this setup. Conserving your CO² is a good idea, but it can end up costing you a pretty penny. When you do not have lights on, do not give your plants CO² because they will not use it. If you set up the release of your CO² to your light timer, during flowering you will only end up using half the CO² you would use at other times. Make sure you do not waste CO² by having any released when your fans are turned on. Seeing as how fans are needed regularly during light cycles, this can also affect how much CO² you end up using. Using bottle forms of CO² is better for the environment because manufacturing CO² can add to the greenhouse effect. Many other processes create CO² so using the bottled forms that capture this byproduct will end up doing the most to help the environment. You can also use a CO² generator or the fermentation process to give your plants their needed CO². Propane heaters are the most common and inexpensive form of CO² generators out there. You just need to make sure the growing location does not get too hot. Rooms that end up requiring venting half of the time will not get much of a benefit from CO² because it will just not sit with the plants long enough to give much of a boost. If your growing location can survive without venting for a few hours, then you will have much more success. Large-scale growers will have to use a CO² generator to get any boosts.
If your room needs little or no venting, you can try either baking soda and vinegar or fermentation. All you do is pour the vinegar over the baking soda and shut the door to the growing room. Once you want the CO² gone, just turn on your vent and it will dissipate. This process cannot be automated, so it is highly impractical for most circumstances. Fermentation will work a little better than vinegar and baking soda, but it will take up much more space than most closets will easily allow. During the fermentation process, yeast is always dying off, so there is constantly some CO² coming out, but this requires the use of a large bin and a lot of sugar. 10 lbs (5 kg) of sugar will last between two and three weeks. Plus it's next to impossible to see how much CO² your plants are actually getting from this process. You can get an idea on how much CO² your plants are getting if you have a tube coming off of the top of your bin that goes into the bottom of a glass jar filled part of the way with water, as the bubbling will give you an idea how much CO² you are able to produce. 1 teaspoon (5 mL) of sodium bicarbonate mixed with a little vinegar will give you a frothy CO² mixture that can help your cannabis plants if you put it in a small growing location. The cheapest way to offer CO² to your marijuana plants is sterilizing a 2L bottle filled mostly with water, combined with 2 oz. (55 g) of sugar and a few cc's of human urine. You could also replace the urine with yeast from a home brew store. Shake up the mixture and keep it around 77°F (25°C) for the next two weeks. You will then notice an increase of about a half an ounce (15 g) for each ounce (30 g) of sugar that you used originally. If you start a new bottle like this every 3-4 days, you will continually be able to cheaply add CO² to your marijuana plants. Supplemented CO² is a huge growth booster to marijuana plants. Our experiments under 250 watt HPS lights showed 15 inches (38 cm) of growth over just eight days with supplemented CO². We recommend using sterilized 1 gallon (3.5 L) plastic milk cartons with a pin-hole poked into the top. If you use tubing that runs into the jar to show your fermentation levels, you will be able to ensure microbes are not getting into your system due to how it is set up.
Alternately, you can use seltzer water sprayed on to the leaves of your marijuana plants two times each day. Some growers do not like this method while others believe it is better than any other method. Logistics say that this is only good in a very small growing location, but if that is how you are able to grow then give it a try! It would be quite expensive if you are using this method on a large crop. Club soda should be avoided whenever possible due to its high levels of sodium that could cause harm to the stomata of your marijuana plants. After 2-3 sprays with seltzer water, make sure you wash the plant down with pure water. This process cannot be automated, but that ends up being beneficial when you consider how closely it makes you pay attention to your marijuana plants. If you MUST use club soda, clean off your plants twice as often. Diluted plant foods can also be sprayed on your marijuana plants while you are giving them more CO². We recommend Formula Flora or Miracle Gro. Just keep in mind that you will be adding to your humidity levels of the room by using seltzer water, so vent off the excess humidity on a regular basis or you may end up with fungi infested plants.
You do not want to spray water over the top of a hot light bulb. Make sure your lights are turned off before spraying. The CO² benefit may not be worth all of the extra time, hassle, danger and expense that an increased yield could offer to some people, so keep that in mind before starting this process. You need to make sure your marijuana plants can get at least 200 parts per million CO² or it will not do them any good. You also need to make sure the environment is ideal for this increased growth, such as proper food and water levels. Some metropolitan areas offer increased CO² sufficient for making supplementation unnecessary. We have heard some growers note a reduced potency when CO² was supplemented around harvesting, so you should likely keep your supplementation to earlier phases of growth.
If you are looking for a simple way to increase your growing speed, quality and yield, try foliar feeding. This works with and without increased CO² around your marijuana plants. Simply create a worm casting tea mixed with bat guano or fish emulsion and any balanced plant food that gives benefits during early growth. (Do not use this later or the mixture will be going into your mouth!) Spray this on your plants until 2-3 weeks prior to harvest. Make sure you rinse off all of your marijuana leaves weekly while this is being used so nothing clogs the plant's stomata. This mixture can be fed to your plants daily, or if you'd prefer, every other day. You will want to spray your plants between 7 and 10 am and again after 5 at night. This is when the stomata of your marijuana leaves are the most open. Try and keep your growing location around 72°F (22°C). If you go beyond 80 °F (27°C), you will likely always have closed stomata. You will want to keep the temperature as close to that as possible with every spraying to keep the benefits maximized. You want to use the best sprayer you can find for this job as the particles need to be incredibly small. You want your pH levels between 6.2 and 7, ideally at 6.5. Baking soda will increase the pH or vinegar will lower it if your pH is slightly off. Spraying small quantities more often is best for your marijuana plants. This will help your plants absorb what they need as they need it instead of drowning them and making them try and cope. Spray when your light is cool to avoid burns to you or your marijuana plants. A combination of seltzer water and liquefied plant food is the best you can offer most plants when feeding through the leaves. Using this type of feeding will also help you totally avoid the lockup of nutrients that often happens with marijuana plants.
If you intend to ingest your marijuana leaves, make sure you clean them off before you dry them so you do not ingest the nitrate salts that cover each leaf.
A negative ion generator has a few benefits. It can help remove some of the odors that come from within a grow room, but they are also known to increase yields and speed of growth. There is not any scientific evidence proving this, but it has been a common outcome for many marijuana growers. With the benefits that both animals and people feel around these machines, it stands to reason that plants would have a benefit of a similar reaction. If nothing else, give it a try. It isn't going to harm anything if you have one in your growing location. Some growers have noticed a decline in the scent coming from marijuana buds when they are picked, but many growers prefer this. All you have to do is clean off the foil plate monthly (and any foil put on your wall near the machine). If you choose not to use grounded foil near your ionizer, you will likely notice the walls around the machine getting darker, requiring a new paint job at some point in the future.
Want to read more about marijuana? Go to our marijuana grow guide.