How to water marijuana plants in soil

Tim Alchimia 2022-09-14
Hi, thanks for your comment Yellowing lower leaves are usually sign of a nitrogen deficiency but can also be caused by various other factors, such as over-watering or under-watering. The problem could also be in the pH of the soil or the water which, if it's not correct, will prevent nutrients from being absorbed by the plant regardless of how much fertiliser is applied. However, from your comment, it sounds like you might have been watering too little. The soil does need to be wetted throughout for the plant to thrive. If you only water around the stem and in the top layer, the roots will not be able to spread throughout the container and the plant will suffer as a result. This could well be the issue here. I would recommend first checking the soil pH, then giving a thorough watering with pH-adjusted water until you get a little runoff (some water seeping through the drainage holes at the base of the container.) hopefully that will solve the problem. If not, try adding a little nitrogen-rich growth fertiliser to the irrigation water. I hope that helps. Best wishes and happy growing.

Tim Alchimia 2021-09-13
Hi and thanks for your comment. We usually recommend stopping fertilisation about 2 weeks before the harvest date. This is to allow the plant to consume all the nutrients in the substrate and to begin to extract the nutrients it needs from its own leaves. In effect, this makes for a smoother tasting end product than would be the case if we fed the plants right up till the last day. Bearing in mind that you just fed them, is there any way to delay harvesting as long as possible to allow the plants to consume the nutrients? That'd be the ideal way forward here, but if you absolutely have to harvest on a pre-decided date then there's no great problem, it may just be a bit harsher to smoke. As for the sprinkler, as long as it's not wetting the plant and the flowers themselves there shouldn't be an issue, but if the flowers are getting wet on a regular basis then you could have mould problems. I hope that helps, best wishes and happy growing!

Tim Alchimia 2020-02-26
Hey Mdot, thanks for your question. Sorry to hear you're having problems with your plants. It's difficult to say what the issue is, I don't have any experience with Miracle Grow soil, but I've read it can be quite high in fertilisers and ought to be enough for at least 4 weeks growth before needing additional nutrients. The symptoms sound a little like it could be root aphids too, which is entirely possible when buying clones from dispensaries (depending on the hygiene standards they operate under). That said, the pH is obviously an issue, so as a first measure I'd recommend flushing thoroughly with plain RO water to see if that improves things. I hope that helps. Best wishes and happy growing!

Tim Alchimia 2018-10-08
Hi Seeley, thanks for your comment. I'm not going to say that the advice you were given is outright wrong, because I'm sure that it has worked well for many farmers over the years, however it's not something I'd personally recommend at all. The idea of burying some un-composted fish under my plants doesn't appeal at all, and I'm fairly sure it would attract unwanted attention from foxes, cats, dogs and other vermin, who would all want to dig up my plants to get to the stinky fish beneath them! Not to mention that the rotting process of the fish would not necessarily produce the correct conditions in the soil for plant development. If you want to use fish scraps so they don't go to waste, then I'd try fermenting them in a jar with sugar and water to make some homemade Fish Emulsion. There are plenty of recipes and instructions online to help you. Otherwise there are plenty of Fish-based fertilisers available on the market, formulated to benefit plants and with accurate dosage instructions to avoid you over-feeding and burning plants. I hope that's cleared things up, all the best and happy growing!

Tim Alchimia 2018-09-05
Hi Louise, thanks for your question. I'm glad your cuttings have rooted well. Keeping them in the shade at first is a good idea, I'd usually have them in dappled shade for a few days before putting them in full sun if growing them outside, well indoors it's the same principal, introduce them to the full power of the lamp over a few days so they don't get stressed. As for temperatures, anything fro 18-30ºC will be fine once they're established, just try not to expose them to extreme heat and make sure the substrate is moist, spraying them can help a lot with that, but once they're rooted it isn't absolutely essential. Their nutrient requirements will depend on various factors, like the type of substrate, growth rate, size of cutting etc, but you can start them off with a quarter-strength dose of organic liquid fertiliser for vegetative growth, increasing the concentration over time as the plant grows. At this stage in the plants life, its main requirement is for Nitrogen. Have a look at our article on deficiencies and excesses of Nitrogen to make sure you're not over or under-feeding your plants, and remember it's easier to rectify a lack of nutrients than to fix the damage caused by excess feeding. All the best with your plants, happy growing!

Tim Alchimia 2018-08-21
Hi Sabine, thanks for your question. The answer would depend on a couple of factors, like what the genetics are, nd at what stage in the life cycle they are. The rain will only pose a problem if your plants are in mid to late flowering period, or if the soil is likely to become excessively waterlogged/flooded. If the plants are sativas, then they are more able to cope with any rain during flowering, Indica plants with their dense compact flowers are much more susceptible to fungal problems when humidity is high. But yes, as a general rule, the rain is perfectly natural for our plants and as long as it's not so heavy as to break branches etc, then you'll be fine! All the best for the season and happy growing!

Tim Alchimia 2018-08-09
Hi Bill, thanks for your question. Well, you can certainly use MIRACLE GROW GRANULES if there's no other option available, although I'm not sure at what rate you'd apply them for cannabis, I've heard they're quite powerful and can burn plants from over-fertilisation. With the huge variety of nutrient products available nowadays formulated specially to meet the nutritional needs of cannabis, why would you use anything else? Personally, I wouldn't use Miracle Grow on anything I intended to smoke or eat. We always recommend using organic fertilisers over mineral/chemical ones, because they give far superior flavour and aroma, and are more respectful of the environment, both in their manufacture process and in their use. Another point to consider is that Scotts/Miracle Grow are owned by Monsanto, the GMO food multinational corporate giant, so there's an ethical question as well, and while I understand that isn't something that's important to everyone, I do think we ought to buy responsibly and choose carefully where we spend our hard-earned cash. I hope that's answered your question, happy growing!

Tim Alchimia 2018-05-02
Hi John, sure you can use bottled water, although it may get expensive over time. Many growers use a Reverse Osmosis filter system to clean the tap water before using it to irrigate, which may be a more economical option in the long term.

Dani Alchimia 2016-09-12
Hi teiar, Normally, growers stop spraying their plants when the buds start developing. In this way, you have less chances to get mold infections and you make sure that the taste of the buds will remain unaltered. All the best!

Dani Alchimia 2016-08-17
Hi adam, Normally, professional growers use RO water and then add all the minerals (nutrients) needed for the plants development, there is no problem at all. If you use distilled water or RO water keep in mind that you should add some extra calcium and magnesium to your nutrient solution. All the best!

Dani Alchimia 2016-08-01
Hi Mikee, You are watering your plants correctly, it doesn't matter how much nutrient solution you need to water your plants when you're mixing the nutrients. You have to follow the instructions of the fertilizer company so you don't overfeed your plants, although using EC meters greatly reduce the risk ofoverfeeding (they measure the amount of salts - nutrients - dissolved in the water). Here you have more info about electro conductivity (EC) and cannabis. About your second question: droopy leaves often come from overwatering your plants. You should water the plants when the upper layer of the growing medium is dry (but do not let all the substrate to dry up!). I would carefully check the composition of your nutrients and see if you have all the macro and micro elements, vitamins, amino acids, etc. needed for proper development. Also, I'd get an EC meter (one of the most useful tools for growing cannabis) and check if you're watering with the corect EC level. Hope it helped!

Dani Alchimia 2016-07-15
Hi Nancy, Check the topsoil layer and water your plants when the first 3-4 cm are dry. Never wait to see symptoms of tension loss on the leaves. If your plant looks like it needs to be watered, then it means that you should have watered before. You'll also realize that the more your plant grows, the more water it'll demand. This article about growing directly in the ground may be useful for you. Hope it helped!

Dani Alchimia 2016-06-27
Hi Yeoolnypotbroo, Sorry, I've never heard of that method. We have neem-based insecticides and also products especially formulated to kill spider mite made of coriander and canola oil. Please tell us how it works if you try it! ;) All the best!

Dani Alchimia 2016-01-21
Hi Rosie, First of all, HID lamps like HPS or MH bulbs are much more sensitive to this type of problems than CFLs or fluorescent tubes, since they reach much higher temperatures. I don't think you'll have much trouble with irrigation water, but you should be a bit careful when spraying: notice that most insecticides/fungicides are photosensitive, so it's always better spraying the plants with the lights off. In this way, we also avoid the problem of shattering our bulb with the water drops. Thus, and as you say, spraying the plants when the lights turn off or about 30 minutes before they turn on is best. All the best!

Dani Alchimia 2015-12-22
Hi andrew, Thanks for your comment and tips, they are always welcome! As Nitrogen is a mobile element, as soon as you see the lower leaves of the plant turn yellow it means that it is lacking Nitrogen on the younger shoots so it is taking it from the leaves. A bit of nitrogen (or a nitrogen-based growth fertiliser) in the nutrient solution will fix the problem. All the best!

Dani Alchimia 2015-12-14
Hi Susan, With "substrate" we mean any media in which plants grow and develop attached by the roots. In this sense, substrates can be fertile (most soils used for pot plants) or inert (coco coir, clay pebbles, rockwool, mapito, etc.). Hope it helped! ;)

Dani Alchimia 2015-09-16
Hi Tony, Basically, you have to water when the soil is still humid but not wet, and water until you see nutrient solution draining from the pot. You can also raise the pot to check its weight, this is a good way to make sure that the soil is being properly irrigated. We have the book Hydroponics for Everybody available in the shop; while it is about hydroponic systems, it explains perfectly the watering needs of cannabis plants and shows different irrigation systems. All the best!