- When you’re just starting out in cannabis cultivation, everything can seem complicated as you begin to explore the various aspects of this activity, since it’s essential to have a basic understanding of the fundamentals.
- Even fairly simple things, such as choosing the right potting soil, fertilizers, and pots, for example, aren’t easy for someone who has never gardened before.
- That’s why today we’re taking a closer look at a topic that may seem basic but still requires a certain approach and a degree of precision: quite simply, how to water a cannabis plant.
It’s quite likely that some of you think this aspect of growing cannabis poses no particular difficulty and that watering a cannabis plant is surely the easiest thing to do. In reality, it’s not quite that simple, and it’s best to familiarize yourself with certain key points in order to maximize the full potential of the cannabis seeds you’ve purchased.
It’s important to realize that this factor will have a direct impact on both the quantity and quality of your harvest. A common question that comes up quite often is that beginner growers, like my friend Jerome, wonder how much water and fertilizer to use when watering their cannabis plants.
It is important to note that this depends on the region’s climate, the type of growing medium and pot used, the pot size, and the specific needs of the hybrid being grown. These are a combination of factors that must be carefully considered in order to achieve a bountiful harvest of the highest quality.
Weather conditions
The climate is undoubtedly the factor that will have the greatest impact on how often you need to water your plants. Whether you’re growing indoors or outdoors, it’s essential to adapt your equipment, tools, and all other aspects of your exciting hobby to the climate in which you’ll be working. It is important to anticipate problems by staying informed about specific weather conditions, so you can best prepare for both planting and outdoor growth.
You’ll need to learn how to manage environmental conditions—including light intensity, temperature, and humidity—both indoors and outdoors. Imagine starting your outdoor growing season by planting your cannabis plants a little too early, when it’s still cold and rain is still frequent, such as in late winter.
In this specific case, you have the perfect conditions for stunted growth, with a fairly high likelihood that fungal diseases and pests will attack your precious cannabis plants fairly quickly. To put it simply, this is where the problems begin…
For all these reasons, it is essential to thoroughly research the temperature and humidity levels that occur both day and night in the geographical area where you are growing your plants. These two factors will give you an idea of the climatic conditions your plants will face at a specific time of year, in addition to various other indicators that we explain below.
If you’re growing in an environment where temperatures are consistently high, you should consider adding mulch to the surface of the growing medium, as well as a small amount of perlite on top of the soil, or mixing the perlite directly into your potting mix.
These components help protect your plants from the heat, as they significantly improve water retention in the potting mix, reduce evaporation, and regulate soil temperature at the same time.
The ultimate benefit of this approach is that it significantly reduces the frequency of watering and the associated water stress. The goal is to optimize water use—which is of paramount ecological importance today—while also maintaining a healthy balance for your roots.
It’s important to provide your plants with the best possible conditions so they can absorb all the nutrients they need until harvest. Be sure to refresh the foliage of your cannabis plants by misting them with water during the growing phase, while taking care not to leave large droplets on the leaves, as this could cause leaf burn. Also, be sure to provide them with the appropriate amount of nutrients for each stage of the plant’s development; this will optimize their potential and strengthen their immune system at the same time.
Learn how to accurately assess and remember the water needs of each of your cannabis plants. It’s very simple: manually weigh a pot filled with dry soil, and then weigh the same pot with soil that’s been watered—using exactly the same amount of water as you would when watering your cannabis plants—and make sure to remember the weight of the pots by lifting them manually.
Here’s the best, most reliable, and least expensive way to assess the water needs of your cannabis plants anywhere in the world—even under the most challenging conditions. The results are clear and immediate; once you’ve mastered this, you’ll never make a mistake. Some might think that an automated drip irrigation system is the best solution to avoid all watering issues, but the reality isn’t always that simple, as there are a multitude of factors to consider.
As autumn approaches—which is also harvest season—you’ll need to adjust your approach accordingly, that is, if rains are frequent and temperatures are fairly cool, you’ll need to space out watering and be vigilant for the appearance of harmful fungi (powdery mildew, downy mildew, botrytis, etc.) in many marijuana crops. Additionally, it’s important to carefully select the seeds you purchase to ensure they’re suited to the climatic conditions in which they’ll grow.
Soil composition
This is an important consideration, as the evaporation rate of the growing medium varies depending on the components used to make it. For example, if you grow plants using a significant amount of coconut fiber, evaporation will occur more quickly than with a soil-based mix.
Using topsoil, light peat, dark peat, or perlite is beneficial because these four materials have excellent water-retention properties, for example. The point is to help you understand that it’s important to adjust the soil mix based on the climate and the specific needs of the cannabis plant you’re growing.
An autoflowering cannabis plant will thrive in a growing medium containing 30% coconut coir, simply because this type of plant requires good aeration in the soil to accelerate both its metabolic processes and growth, since the growth period for an autoflowering plant lasts only about twenty days.
It is therefore essential to provide the plant with as many resources as possible in the shortest amount of time to maximize its potential. For these same reasons, it may be beneficial to use pots with a capacity of 15 to 20 liters when growing autoflowering plants outdoors, as well-aerated soil and this amount of growing medium will ensure a high-quality, maximized yield.
Unlike autoflowering plants, photoperiod cannabis varieties prefer soil with a denser, moister texture. They thrive best in a stable soil mix and are less tolerant of water shortages than autoflowers. It will therefore be necessary to carefully balance both the frequency and the amount of water and nutrients during each watering session over the course of several weeks. Also remember to test the pH level if you’re using tap water.
Plant size and pot capacity
These two factors are directly related, because the greater the substrate’s capacity, the more the root system can develop, and consequently, the larger the plant will grow. It will also be necessary to adjust the corresponding amount of water and nutrients.
A common mistake beginners make is this: if you plant a young plant that is 1 to 3 weeks old in a large pot with a capacity of 25 to 50 liters, for example, it will have relatively low water requirements at that stage, compared to its water needs during the flowering phase a few weeks later. It is important to know how to adapt to the situation in all circumstances.
In this specific case, logic dictates that infrequent watering will be necessary during this period; a single weekly watering will certainly suffice, though you must remain vigilant regarding the weather conditions at your growing site. As each plant continues to grow and thus increases in size, you will obviously need to adjust the amounts of both water and nutrients accordingly.
A common mistake many growers make at the start is that they drown the roots in water because the potting mix is so saturated; this significantly slows down the growth of the cannabis plant.
This can be explained by localized root asphyxia, meaning that a lack of oxygen in the soil leads to problems with water and nutrient absorption at the root level. For this very reason, the minimalist yet highly effective watering tip mentioned earlier proves to be a valuable aid right from the start.
However, you should be careful not to leave your roots in overly waterlogged soil for too long, as this could lead to a fungal disease called fusarium, which in this case is caused by root rot. The first symptoms are usually slowed growth in your cannabis plants.
The one thing you must avoid at all costs during the first three weeks of growth is overwatering the growing medium, as this could drastically slow down the growth of your cannabis plants. It is essential to ensure a balance between well-moistened soil and oxygenated soil, without letting it become completely dry. Limiting the size of the plant’s structure and root development also means reducing each plant’s yield potential.
If you overwater during this period, it could also lead to serious problems, such as a weakened immune system in the plant, or even root rot, which could ultimately result in the appearance of certain fungi and pests. This sets off a chaotic chain reaction. It is of the utmost importance to be meticulous about how you water; it is true that this requires a certain learning curve.
Remember the intuitive method of manual weighing or estimating weight by hand—I assure you it works even for large-scale container gardening. If a pot feels unusually light for its size and contents, you can conclude that the soil is far too dry.
On the other hand, if it feels unusually heavy, it means the soil is waterlogged. If the leaves are drooping, that’s a very bad sign, as it means the plants are severely dehydrated—you need to act quickly and water them immediately!
It’s not a good idea to let the soil dry out completely, because it will take some time for the soil to regain its moisture-retention and water-conducting properties, which causes stress to the plant since it isn’t properly hydrated. And as our dear Jerome would say, that’s no small matter.
It is important to determine the correct watering frequency for each growth stage, so that plants receive the right amount of water along with all the nutrients they need to reach their full potential. These tips also apply to growing high-CBD plants from seed. Always remember to check both the temperature and the pH of your tap water, as these can vary significantly from one region to another.
It is important to always monitor the health and appearance of your marijuana plants’ leaves during cultivation, as they reveal information that is worth analyzing, such as various deficiencies in water and nutrients throughout the different stages of the plant’s growth cycle.
It will require you to demonstrate strong analytical skills week after week in order to identify areas that are lacking and those that are naturally logical. You must always remember that every problem has a solution—this is a fact of life. Learn to identify the various color changes that appear on the leaves and, above all, what they indicate. Most of the time, they signal deficiencies or excesses in nutrients or water that your marijuana plants are experiencing.
You will also need to be particularly vigilant as the end of the flowering period approaches, because as the ambient humidity naturally rises with the arrival of heavier rains in early September—which is also accompanied by a drop in temperatures—the risk of mold-related problems is high. It will therefore be necessary to reduce the amount of water used when watering, depending on the humidity in the air week by week at this stage.
