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Unitfarm Indoor Garden Knowledge

A Beginner’s Guide to Controlling the Smell of Cannabis Plants

When you grow more than a few plants indoors, you may notice that they give off distinctive aromas from the soil, nutrients, and the plants themselves. The scent may be distinct enough that you don't necessarily want a Gladys Kravitz-type turning up her nose at your personal interests.This becomes particularly important now that growing cannabis is legal in an increasing number of locations. Even if the day comes that all states approve growing marijuana, some varieties release quite a bit of compounds called terpenes in the flowering stage, and it might just bug you.Unitfarm LED grow lights have been proven to increase the production of THC and CBD in both lab test and in practice when testing our lights against other lighting technologies both traditional plant lights such as HPS as well as other competing LED grow lights. Along with these other compounds, terpine / odor production may also increase under Unitfarm LED lights.

If you'd rather keep your horticultural evidence below the radar, here are a few ideas for both casual and serious growers.Basic household odor neutralizers aren't highly effective.Sprays, plug-in air fresheners, and other household products can knock down the aroma of a plant or two, but they don't last long and aren’t that effective on stronger-smelling varieties. ONA Gel is a specially blended product that is popular with many growers because it's easy to use and lasts for 4-6 weeks. Don't use these products in the same room as your plants, though, because they can become absorbed by the plants which will change the taste of the harvest. Confine the use of ONA Gel to adjoining rooms only.Home air purifiers like ionizers can handle mild household odors, but can't stand up to the fragrance of most aromatic plants.

Commercial Air Cleaners

Experienced growers use filtration units with activated carbon to scrub the air of unwanted odors. They're what you need if you want to really neutralize the scent and are the only choice for odor control in larger setups with grow tents or dedicated grow rooms.

Since these environments need temperature control and air circulation equipment anyway, adding a filtration system is a relatively simple proposition. Find the duct size and CFM rating of your ventilation system and choose a filter that will fit and work properly with your system's flow rate. Mount the unit where it's easy to access when it's time to change filters.

Choose a Plant Naturally Low in Odor

Different strains give off different smells, so give yourself a head start on odor control by picking a variety that's less fragrant but still flavorful and potent. Here are a few to consider:

• Blue Mystic— A hybrid strain created by crossing Northern Lights and Blueberry for exceptionally low odor.

• Durban Poison— The South African sativa is nearly odor-free yet has very high THC levels.

• Northern Lights— A low-aroma variety developed specifically for indoor growing, it's both flavorful and potent.

• Polar Express— An ideal indoor variety, Polar Express has been crossbred to be compact, flavorful, and extremely low-odor.

• Shark's Breath— Easy to grow and high yielding, this Indica-dominant variety is very low in aromatics when flowering.

What NOT to Do

Your plants need fresh, well-circulating air to thrive. Stagnant, poorly conditioned air is a sure recipe for disaster, so don't be tempted to seal off your growing area to contain odors without providing an adequate fresh air and ventilation system. If you're able to vent to the outside of your building, that's your best choice for odor control. Just be sure to locate your vents where they won't intrude on unwelcoming nostrils.

Light Cycles Explained

There are two phases to the growth of most flowering plants: vegetative and flowering. The vegetating cycle focuses on establishing a solid root system, a strong main trunk, and ample foliage to absorb the light that’s essential to the photosynthetic process. If you're starting from seed, you can get by with less light intensity until active growth starts; heat is more an issue. Keep the seed bed warm, but not hot, and give enough light to nourish the seedlings without scorching them. If you're starting seeds full-spectrum LED grow lights are a good choice because they give all the light needed without overheating concerns. Insufficient light will result in tall plants with long internodes, so don't use a weak light that causes the seedlings to reach for it, creating "stretch."

Once plants are established and in the vegetative phase, they require plenty of light in the right frequencies to stimulate growth. Outdoors, the sun provides more than enough light in all frequencies, but indoors, it’s up to the grower to give plants the quality of light they need. Leafy plants like Cannabis want a good amount of blue and red light in the proper wavelengths for optimal growth and bud production, and while mixing various light sources can approximate it, the simplest and ultimately most economical way is through the use of properly designed full-spectrum LED grow lights such as our LED grow lights featuring the Phyto-Genesis Spectrum™.

While Cannabis plants don't have a "sleep cycle" per se, many growers feel that at least some time in the dark lets them relax and catch up on some other processes that improve plant quality such as root development. At the minimum, Cannabis plants require less than 12 hours of dark to stay in the vegetative cycle, so a good approach is 18 hours on and 6 hours off during vegetation. At the very least, it will save considerably on energy used for lighting and ventilation with very little effect on plant growth.

The flowering phase in Cannabis is triggered by the light/dark cycle. It is started by changing your cycle to 12 hours on and 12 hours off. During this phase, the plants will continue to grow vigorously and require even more light because of their size. Some growers switch to HPS at this time because the plants need more red light than they did previously, but with full-spectrum LED grow lights, the need to change sources is eliminated, saving time, bother, and money as well as the need to control the large amount of heat produced by HPS lamps.

While it's possible to give plants too much light, it's not likely with an indoor grow room because you would likely overheat it and waste energy. Practically speaking, a minimum of 37 watts per square foot is a minimum, and 65-75 watts is your upper limit for our LED grow lights.

Rather than bogging down in botany, keep your growing simple by following three guidelines: use full-spectrum LED grow lights for all cycles, keep them on at least 18 hours during vegetative growth, and cut back to 12 on and 12 off for flowering. Then sit back and enjoy your harvest.

LED grow lights are the clear choice for serious growers of indoor vegetation of nearly any type.


Before we cover how to properly adjust pH, it is important to remember the chemicals we will be working with are caustic and need to be handled carefully.

• Never combine concentrated pH Up and pH down.

• Never add water to acid, only acid to water.

• Do not store acid (pH up) and bases (pH down) in the same area.

• Do not consume or allow pH up or pH down to contact your skin. If a strong acid or base does come in contact with skin or clothing, wash the area immediately. Contact poison control if ingested or if it contacts your eyes.

• Always dispose of hazardous materials properly and according to local laws and regulations.

• Never work without the proper protective gear, especially protective eyewear and gloves.

Proper Measuring and Mixing of Nutrients

Individual fertilizer manufactures may have different, very specific pH requirements. We highly recommend following all manufactures' guidelines closely. Too many gardens have suffered from "Mad Scientist Syndrome", more is not better and the nutrient manufactures should be the experts and include detailed instructions for a reason.

1. Water- Fill your reservoir, bucket, or other container with plain, cold water. Use a carbon filter (such as a Hydrologic Small Boy) or reverse osmosis filter (such as Hydrologic Stealth R.O.) if your water quality is poor. Allow the water to reach room temperature. The addition of an air stone or water pump at this time will help oxygenate the water and raise its temperature, while helping to get rid of (off-gas) any residual chlorine or other undesirable dissolved gasses.

2. Nutrients- Start adding the concentrated nutrients in the water one at a time. Never mix nutrients together at full strength. At this time you can use a water pump or air stone to help mix the solution, or simply stir vigorously after each addition. If using bottled or dry nutrients, without organic compounds, the solution should be agitated well for at least 5-10 minutes or until completely dissolved. In some cases, days of mixing and aeration may be necessary for complex organic formulas, and compost teas. Thoroughly mixing the fertilizers and other additives together until they are completely dissolved ensures a consistent, accurate reading. One rule of thumb, if your nutrient program includes multiple parts, the bottle of "Micro" nutrients is typically added first. Lastly, always wash out measuring utensils before adding the next nutrient or additive.

3. Adjusting pH- After your fertilizer is prepared to the desired strength (you can test strength using a ppm or EC tester), and the temperature is stable, start by testing the solution's pH. Use a digital pH pen for the best readings, setting the pen or wand in the liquid until it is the same temperature, then depending on the result, add a very small amount of pH Up or pH Down. Stir the solution and wait 5-10 minutes while it mixes with the fertilizer, and measure again. Keeping track of how much you added the first time and the resulting change will give you a general idea of how much pH Up (base) or pH Down (acid) you will need to add to reach your target number (5.7-6.2). Some utensils we have found particularly useful when working with acids and bases include plastic 1-5 ml pipettes, plastic syringes, and small measuring cups. Glass accessories should be avoided as they can cause inaccurate readings during calibration, and can have dangerous interaction with strong acids. As a side note, some additives and nutrients are very acidic or alkaline by nature. When using silicon (Si) or products with fulvic/humic acids for example, special attention should be taken.

Adjusting Water pH Without Nutrients

When you don't need to fertilize your plants but they still could use a drink, adjusting the pH of the "plain" water is still important. With or without nutrients, the pH of whatever you pour onto your plant matters. If you are using tap water or filtered water (not RO water PH or distilled water) to properly adjust the pH, follow steps #1 and #3 from above. It is important to know that using Reverse Osmosis, Distilled, or other "0 ppm" water by itself is bad for plants, as it leaches away essential ions. We recommend never watering with "pure" water without first adding a small amount of nutrient or additive to act as a "buffer", or it could kill your plants. After adding the buffer, follow steps #1 and #3 to attain proper pH.