Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

problem. One of the main causes of over-watering is poor air ventilation! The plants need to transpire water into the air. If there is nowhere for this wet, humid air to go, gallons of water are locked in the grow room air. Well-ventilated air carries this moist air away, replacing it with fresh, dry air. If using trays to catch runoff water, use a turkey baster, large syringe, or sponge to draw the excess water from the tray. Signs of overwatering are: leaves curled down and yellowed, waterlogged and soggy soil, fungal growth, and slow growth. Symptoms of overwatering are often subtle, and inexperienced gardeners may not see any blatant symptoms for a long time.
    Marijuana does not like soggy soil. Soil kept too wet drowns the roots, squeezing out the oxygen. This causes slow growth and possible fungal attack. Poor drainage is most often the cause of soggy soil. It is compounded by poor ventilation and high humidity.
    Underwatering is less of a problem; however, it is fairly common if small (1-2 gallon) pots are used and the grower does not realize the water needs of rapid growing plants. Small containers dry out quickly and may require daily watering. If forgotten, water-starved plants become stunted. Once tender root hairs dry out, they die. Most growers panic when they see their prize-marijuana plants wilt in bone-dry soil. Dry soil, even in pockets, makes root hairs dry up and die. It seems to take forever for the roots to grow new root hairs and resume rapid growth.
    Add a few drops (one drop per pint) of a biodegradable, concentrated liquid soap like Castille® or Ivory® to the water. It will act as a wetting agent by helping the water penetrate the soil more efficiently, and it will guard against dry soil pockets. Most soluble fertilizers contain a wetting agent. Apply about one-quarter to one-half as much water/fertilizer as the plant is expected to need, and then wait 10 to 15 minutes for it to totally soak in. Apply more water/fertilizer until the soil is evenly moist. If trays are underneath the pots, let excess water remain in the trays a few hours or even overnight before removing it with a large turkey baster.
    Another way to thoroughly wet pots is to soak the containers in water. This is easy to do with small pots. Simply fill a 5-gallon (19 L) bucket with 3 gallons (11 L) of water. Submerge the smaller pot inside the larger pot, for a minute or longer, until the growing medium is completely saturated. Wetting plants thoroughly insures against dry soil pockets.

Put a saucer under the plants to retain irrigation water, if they run out of water quickly.

Plants in small containers require more frequent watering.

A water wand with a breaker head mixes air with irrigation water just before applying.
    Having a readily accessible water source is very convenient, and it saves time and labor. A 4 × 4-foot garden containing 16 healthy plants in 3-gallon (11 L) pots needs 10 to 25 gallons(40-100 L) of water per week. Water weighs eight pounds a gallon (1 kg per L). That’s a lot of containers to fill, lift, and spill. Carrying water in containers from the bathroom sink to the garden is okay when plants are small, but when they are large, it is a big, sloppy, regular job. Running a hose into the garden saves much labor and mess. A lightweight, half-inch hose is easy to handle and is less likely to damage the plants. If the water source has hot and cold water running out of the same tap, and it is equipped with threads, attach a hose and irrigate with tepid water. Use a dishwasher coupling if the faucet has no threads. The hose should have an on/off valve at the outlet, so water flow can be controlled while watering. A rigid water wand will save many broken branches while leaning over to water in tight quarters. Buy a water wand at the nursery or construct one from plastic PVC pipe. Do not leave water under pressure in the hose for more than a few minutes. Garden hoses are designed to transport water, not hold it under pressure, which may cause it to rupture.

A water wand with an air breaker head oxygenates water and splits it into many streams.

Use a filter with drip systems!

Spaghetti tubing is anchored in the growing medium with a spike. A stream of nutrient solution flows out the tubing and percolates down through the growing medium.
    To make a siphon or gravity-fed water system, place a barrel, at least four feet high, in the grow room. Make sure it has a lid to reduce the evaporation and the