First, we need to talk about the types of water you can use to water you cannabis plants.
What type of water should I use?
There are a few types of water you can water your cannabis with.
- Distilled water
- Rain water
- Tap water (left out for at least 24 hours)
- Reverse osmosis water
This is water that is purified by evaporation and condensation. This removes any impurities and minerals from the water. If you use this, you’ll need to add supplemental calcium & magnesium. Distilled water is great for controlling your ppm as it starts at virtually zero. Although, using only distilled water to water your plants and fill your humidifier can get pretty costly.
Using rain water has several benefits over tap water. It doesn’t contain any chlorine or fluoride that is added to the tap water. Rain water also contains less magnesium and calcium concentrations than harder tap water. It also saves you on the cost of water. You will have to buy a rain barrel to collect the rain, but it is a small investment (roughly $50CAD). You may want to add some supplemental calcium and magnesium if you’re using rain water, but it does contain some already.
If you use tap water, you need to let it sit out for at least 24 hours. This allows the chlorine to evaporate out of the water. You also need to find out how hard your water is. You can usually find out on your city/town website if they have one. You can also contact your local water treatment company to find out the mineral profile of your water. If your local water is soft enough, you can use it without any filtration. You may want to add some supplemental calcium & magnesium, depending on the levels in your water already.
Reverse osmosis water
Reverse osmosis is a water purification process that uses a semi-permeable membrane to remove unwanted particles, ions and molecules. This is used to purify hard water which contains higher concentrations of magnesium, calcium and other dissolved minerals. This requires the purchase of a reverse osmosis filtration system. Unless you need one for your drinking water, I don’t recommend buying it solely for your plants. You will need to add supplemental calcium & magnesium to your RO water.
Regardless of the type of water you use, it is always important to pH balance your water before giving it to your plants. Always do this step last because liquid fertilizers and additives can effect the pH.
How often should I water my plants?
When it comes to watering your plants, you should always check the soil before watering. You should do the knuckle test. Simply, put your finger into the soil up to your first knuckle or about an inch deep. If it’s wet or moist, let it dry out for another 12-24 hours before watering. If it’s dry, it’s time to water the plants. If you’re using coco coir, the top inch doesn’t have to dry out completely. You should aim to water the plants every 1-2 days. But, don’t water if the top inch is still wet. If your medium stays wet for 3+ days, adjust the amount of water given at each watering. If it takes 5+ days to dry out, then you may have an issue with drainage.
To correct drainage issues:
- Mix in extra perlite to allow better drainage
- Use smart pots, air pots or fabric pots to promote oxygen at these plants roots; These pots also helps prevent overwatering
If you’re adding liquid fertilizer to your water on a regular basis, you should water until you get a decent amount (about 10%-20%) of runoff in the tray. This ensures that you don’t get a buildup in the soil of nutrients. You can simply suck up the excess runoff up with a shop vac. If you are using super soil or heavily amended soil, you want to avoid any runoff. Otherwise, you’re losing some nutrients in the runoff.
How much water should I give my plants?
When watering your plants you should make a small perimeter around your plant. With very young seedlings, I use a spray bottle to water them because they don’t require much water at that stage. I’ll spray them between 2-4 times a day depending on the humidity in the tent.
Once they get a little bigger, I use a water bottle to water them because they require a little not more water as they grow. I will water them like this about once a day.
Once they are bigger than this seedling, you can gradually increase the amount of water a little bit at a time. You add a little more water each time the plant grows larger. When the plant gets to be about a foot high, you can water it with roughly 1 liter at a time. By the time they are large plants, they can get watered roughly 1.5-1.75 liter at a time. You will have to experiment with the amounts as you grow, but once you get the hang of it, it comes second nature.
If your plants are drying out everyday or multiple times a day then you should consider transplanting into a bigger pot or increasing the amount of water. If you start your plants in solo cups, you should transplant them after approximately 2 weeks or when the leaves extend past the cups edge.
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