Originally posted on Future Harvest Nutrients Blog
Indoor Vs. Outdoor: Which Is Best?
This topic has long been a source of debate among growers, though it is a purely subjective personal preference based upon factors specific to each grower. This article will not determine that one method is superior to the other, because we believe the best method is the method that works for you. We'd rather provide the information one needs to make an informed decision when considering indoor and outdoor growing.
Growing outdoor cannabis has numerous benefits. In most parts of the world, nature provides all the necessary elements for cannabis to grow. This makes outdoor growing an affordable and environmentally sustainable option for many growers.
Due to an unrestricted growing environment, plants can reach enormous sizes, producing massive yields per plant. It is an undeniable truth that artificial light cannot reproduce the intensity of sunlight and the energy it provides your plant is a free natural resource.
If you are considering outdoors, you should start off simple with Future Harvest's 1-part Easy Plus Series for soil and coco!
Environmental Considerations for Outdoor Cannabis⠀⠀⠀⠀⠀⠀
The best climate for cannabis provides warm to hot summers, followed by a dry, mild fall. Unless you're growing auto-flowers, cannabis is photoperiodic which means it will only trigger flower production if given 12 hours of darkness.⠀⠀⠀⠀⠀⠀
If your strain requires 9 weeks of flowering, then 9 weeks of 12-hour nights will be required to reach harvest. Climates with short days can use low-wattage supplemental outdoor lighting to keep their plants from flowering. Choose your strains based upon the characteristics of your climate.
Cannabis is extremely vigorous and can thrive in many different conditions. An outdoor grower should generally wait to begin growing outdoors in the spring until temperatures exceed 10 degrees Celsius for seven days in a row. Many growers will germinate their seeds in-doors to be transplanted once their plants have hardened off and a healthy root system has been developed.
You want to make sure your garden gets a lot of sun and is not situated in a heavily shaded area. Partial-sun can work, though it is not ideal, just as long as the canopy is provided a minimum of six hours of direct sunlight. Ideally, you want 9-12 hours of direct sun per day.
Outdoor plants are vulnerable to wind damage during a storm if not supported. Stakes, trellises and tomato cages should be used during flower to prevent the spread of powdery mildew, support heavy flowers and mitigate potential wind damage.
Outdoor plants are much more susceptible to disease and pest issues. Fluctuations in temperature and humidity can often lead to powdery mildew.⠀⠀
Pests that cause tissue damage can spread pathogens and stunt growth. Prevention is always the best defense against pests and disease when growing in an outdoor environment.
This could include thinning your canopy to provide airflow through the plant or using pots outdoors to reduce the risk of infestation from common rootzone pests in your natural environment.
Physical barriers can also be employed to keep larger pests away!
The structure, density and quality of your soil will make a world of difference in an outdoor grow! Soil that is compacted will limit root production. Soil that is far too porous, with large particulate (like sand), will dry out quickly between irrigations.
A light loam soil of about 20% clay and 40% silt and sand, is perfect for growing cannabis outdoors. The clay and silt, being smaller in particulate size, hold moisture and nutrients better than sand, therefore they retain more moisture between irrigations on hot days.
In terms of nutrients, a great place to start is either with Future Harvests Personal Grow Box or Personal Flower Box!
Perhaps the key difference between indoor and outdoor growing is the way in which plants access their nutrients.⠀
In a hydroponic system, nutrients are provided to a plant in readily available form.
In nature, plants rely on microbial activity (decomposers) to break down organic matter, releasing the carbon stored within in a form that can then be taken up by the roots.⠀
Many hydroponic stores now sell pre-mixed organic soils that can be used outdoors if need be.
Growing in soil tends to be less of an exact science than hydroponic growing because of the variables involved, but many organic growers claim to experience an enhanced flavor and aroma to their cured flower.
Outdoor cannabis flower will have a different appearance to indoor cannabis, as outdoor cannabis is exposed to debris in the air, storms, temperature fluctuations and humidity fluctuations.
Indoor growing allows for complete control over atmospheric conditions. This makes everyday of plant's life a nice sunny day with perfect temperatures for growing!
High intensity lights like LED’s and HPS bulbs replace sunlight by providing radiation within a spectrum range that has been designed deemed the most important for photosynthesis.
Environmental controls, like heating, cooling, air exchange and timed lighting cycles, give growers the ability to dial-in optimal conditions for growing.
Hydroponic solutions provide crops with readily available nutrients that do not need to be broken down before becoming a bio-available source of nutrition. This means that growers achieve shorter crop times with higher yields.
With all the benefits of indoor growing, there are drawbacks like energy consumption, the cost of materials and the general maintenance involved.
Before growing indoors, new growers should consider...
The amount of cannabis one will be able to grow is dependent on the amount of overall square footage at their disposal.
Many recreational growers utilize grow tents or grow boxes in order to achieve a perfect micro-climate while others will design an entire grow room. Ceiling height should also be considered, as a low ceiling may affect your lighting choice, strain selection and plant training techniques.
Air exchange in indoor growing is crucial, you do not want stagnant air in your environment. This means that in most applications an air intake fan will be needed as a source of fresh air as well as an exhaust fan to ventilate air from your growing environment.
The complexity or simplicity of how your plants are watered is entirely up to you. One can water by hand or accomplish the same result with a fully automated recirculating hydronic system.
Hydroponic methods alone present a wide range of choices to make and it is vast subject that could be a blog of its own, but the way you irrigate should be specific to your growing situation and what works for you!
It is a good idea to always monitor the pH and EC of your irrigation water!
There are multiple methods and meters growers choose from to help you keep the acidity/alkalinity and concentration of dissolved solutes of your irrigation water at plant friendly levels.
If you are using hard water, products like Future Harvest’s Holland Secret Hard Water Micro will neutralize the bicarbonates in your water to ensure the bioavailability of micronutrients to your plants.
Heating and Cooling:
Due to the nature of high intensity lights like HPS bulbs, many growers experience climbing temperatures in their growing environments. It is important to keep temperatures roughly between 18 and 30 degrees Celsius, with peak photosynthetic potential occurring at a leaf temperature of 27 degrees Celsius.
Ventilation can play a large part in keeping temperature under control, and growers will often use cooling tube fixtures with HPS light to force cool air through the fixture and purge the hot air from your exhaust.
Cannabis will thrive within a wide range of relative humidity as long as they remain somewhat constant. Because seedlings have small root systems with limited root absorption, a higher relative humidity of around 70% will provide increased absorption of atmospheric water vapor.
Once a healthy root system has been established, it is beneficial to slowly taper humidity levels to achieve an optimal relative humidity of 40% (give or take) during flowering. ⠀
Today’s indoor growers can choose from a wide range of growing lights. The reason why specialized lighting is required is because plants require a higher intensity of light than the average household bulb.
They are also designed to produce light within a known photosynthetically active range (PAR) measured in nanometers. Considering a cannabis plant’s life cycle is beneficial when considering your lighting choices.
Seedlings have less sites of photosynthesis due to a lack of foliage. One can germinate seeds and propagate cuttings under considerably less intense lights like compact fluorescent bulbs or T5 fluorescents placed in close proximity to your cutting or seedling.
For vegetative growth, indoor growers often choose lights like full-spectrum LED’s and metal halide bulbs, to mimic the spring sun’s cooler spectrum of blue and green. During the vegetative phase, blue light will help prevent from stretching.
Flowering plants love the red and far-red light that mimic the late summer/autumn sun. A metal halide bulb can be replaced with HPS bulb during flower to accomplish this or one can simply engage the red-light spectrum of their LED fixture when switching to a 12hrs on/off lighting cycle.
It is important to remember that both metal halide bulbs and high-pressure sodium (HPS) bulbs generate a significant amount of heat, and may require a cooling tube type fixture to keep temperatures optimal. One should also try to keep a distance of about 2 feet between the light and the canopy to prevent burn or bleaching during flowering.
The intensity of your lights (PPFD) is extremely important in regards to maximizing flowering production and yield. Photosynthetic photon flux density (PPFD) is measured in micromoles per second per meters squared.
All you need to know is that light manufacturers will often provide a PPFD rating and your target should be to achieve 700-900 µmol/m2 at canopy level!
Of course, at Future Harvest we have all your plant nutrition needs covered. First-time growers need to understand that because soil and hydroponic nutrients are accessed by plants differently, their choice of media should be considered when using plant nutrients.
For example, soil growers will require slow-release or organic fertilizers as opposed to growers using soilless mix and hydroponic solution. When using plant nutrients for the first time, always follow the dilution rates suggested by the manufacturer.
Over-zealous use of nutrients can lead to nutrient burn and can even prove fatal to plants in some cases.
An EC meter will tell you the concentration of nutrients in your solution and is a further protection against both nutrient deficiencies and nutrient burn. Utilize pH adjusters to dial-in your pH to the plant friendly optimal range of 5.8-6.3!