Figuring out when to water your plants can be tricky, especially for new growers, so hopefully this quick thread will help.
After over-feeding, the most common cause of plant failure is over-watering! The roots need air as well as water and should not be constantly drenched. The symptoms of over-watering are unfortunately similar to under-watering... the plants wilt, the leaves and branches sag, brown patches appear on the leaves, the roots start to rot and if left untreated the plants die.
How often should i water the plants, what time of day and how much should i give them?
There is no definite answer as it depends on many things:.. warmth of the grow-room, the light's used and distance from the plants, humidity, size of pots, growing medium (soil) and various other factors.
There are a few things to look for when deciding when to water:
* Is the pot very light? - Around 90% of the weight of compost is water, so if the pot is light and much easier to pick up than normal, a watering is needed.
* A gap around the edge of the soil in the pot? - Soil shrinks as the water is used up, so a gap around the edge of the soil is a good sign that water is needed.
*Does the soil stick to a pencil? - Gently push a long pencil into the edge of the soil in the pot, if it is not damp with bits of moist compost stuck to it when you take it out, then a watering is needed.
* Wilting? - A plant will wilt (droop) when it needs watering, usually starting at the lower leaves working up the plant. If your plant is wilting then a watering is urgently needed.
What time of day? - Personally I prefer to water when the lights come on rather than when the lights are off (or due to go off), simply due to humidity.
Humidity rises at night which if not kept in check can cause problems, watering just before the lights go out means there's more surface water on the soil which will increase the humidity in the grow room a lot.
Watering in the 'day' will keep the humidity relatively constant.
How Much?
Again this can vary dramatically depending on pot and plant size etc, but what most growers do is: with a tub/tray under your pot, water *slowly* until the surplus runs from the drainage holes at the bottom of the pot... allow the pot to stand in the surplus water for 10 minutes to soak up any more that is needed before emptying out the run-off tub.
The smaller your pots the less water you might need to give... a little 4" starter pot for seedlings under a CFL light may only need watering once a week with half a pint of water, whereas a 10 Litre pot holding a big plant under a HPS light may need 3 or 4 litres of water 2 or 3 times a week!
Remember, wait until the pot is light and the compost dry before watering again, and just because the top inch of soil is dry doesn't mean that the soil around the roots is!
As with feeding your plants, a good rule of thumb when watering is: better to give less than too much!
Hope that helps a few of ya!
Peace.
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