Air, temperature and humidity are closely linked and all are important
factors in providing a good environment for your plants. Outdoor
growers are at the mercy of the elements so control of the environment
is limited for them, for indoor growers however things are different.
Luckily the environment in your average heated house is close to
the ideal conditions for cannabis growth. This makes indoor growing
the best option in cooler climates like the UK.
Unlike us plants can`t move to get fresh air. When kept inside or
in a greenhouse they can suffocate if the air around their leaves
is not changed. During the night when plants are working on their
roots and not producing any of their own oxygen the need for fresh
air is even more important. To get the best from your plants therefore
use circulating fans and ventilate or use extraction fans day and
Cannabis plants need to be able to extract Carbon dioxide (CO 2)
from the air to use as a building material. The amount of CO 2 a
plant can use depends directly on the amount of light it receives.
Low light gardens (around 1000 lumens per sq. ft) will not be able
to use any more CO 2 than is available naturally in the air. Higher
light gardens can use more CO 2 but only if it is delivered in the
right place, at the right time, at the right temperature and in
the right amounts. Unless you have no fresh air ventilation at all
or are a commercial grower CO 2 injection can be a lot of hassle
and expense. It`s easier just to constantly pump in fresh CO 2 laden
Oxygen For Roots
For healthy growth you need to make sure a plants roots have direct
access to oxygen on a regular basis. In pots this means allowing
the medium to dry out a bit between waterings. In hydroponics it
means making sure you don`t saturate your medium too much. Flood
and drain only once or twice a day or use NFT systems where most
of the roots are out of the medium anyway. Healthy roots are bright
white while roots starved of oxygen will start to go brown.
Talking to plants
Simply being with your plants is an easy way to improve their
air. Humans breathe out CO 2 all the time so plants really do benefit
from being around people. Sound vibrations from talking or music
will also strengthen a plants stems. Keep it to yourself but talking
and playing music to your plants will help them grow bigger and
Cannabis can survive in temperatures ranging from freezing to 100
degrees but such extremes will slow growth and lower potency. For
the best results during a plants day time keep temperatures between
70 and 85 degrees. At night aim for between 50 and 70 degrees. If
heat becomes a problem try timing the light cycle to come on at
cooler times like during the night. Using a thermometer with a min
max setting will also make sure you are aware of temperature fluctuations
that take place when you are not around.
Extra Heating Indoors
Adding more HID lights is a good way to increase the temperature
in a grow room. They kick out nearly as much warmth as a heater
of similar wattage but also have the advantage of extra light. If
your heat problems are during the plants night time use a standard
heater instead but make sure any 'on' light is covered to stop it
interrupting or interfering with the plants dark cycle. Simply raising
plants off the ground on a table or pallets allowing a 'sink' for
cold air will also help.
Extra Heating Outdoors
Water in a good storer of heat so areas around large expanses of
water are always a few degree`s warmer than inland areas. You can
mimic this by placing water storage barrels near outdoor plots.
Paint them matt black and they will warm up during the day and release
their stored heat during the night, all for free.
The humidity is the amount of moisture in the air, the warmer the
air the more moisture it can hold. In a hot grow room even of a
modest size plants could be chucking litres of water into the air
every day. This water laden air won`t effect growth directly but
it needs to be extracted or vented out to avoid problems with moulds
and fungus. Ventilate outside if possible as the moist air will
condense on cooler inside walls causing damp like problems. Aim
to keep humidity levels between 40 and 60% all the time as lower
levels will also invite problems. These range from dry air loving
pests like spider mites to a slowing down in CO 2 and light uptake
if the atmosphere gets really dry.
Help Leaves Breathe
Cannabis plants use the underside of their leaves to breathe. Fans
blowing up from underneath plants will help them maintain adequate
levels of CO 2 where they need it. They will also also help to keep
down the humidity levels under the canopy.