Personalized attention +34 96 206 62 98
Free shipping to Iberian Peninsula from 30€
9/10 Rating
Discreet shipping
Cannabis cultivation has evolved significantly in recent years, along with the techniques and technologies used to optimize its growth. One of the most effective and sustainable methods for watering your plants is **drip irrigation**. Although this technique has been used for decades in agriculture, it has gained popularity in urban gardens and home cannabis grows due to its efficiency and precise control. But the question remains: How to calculate drip irrigation time?
There’s no one-size-fits-all answer. It depends on several factors, such as plant size, type of substrate, and environmental conditions. That’s why calculating the proper watering time is crucial. While it may seem complex, it can be easily done with the right knowledge and tools.
What is drip irrigation?
Drip irrigation delivers water directly to the root zone of plants, avoiding unnecessary waste and promoting more efficient nutrient absorption. Though not a new technology, its roots trace back to ancient times when basic systems were used to distribute water to crops. Since its early use in arid regions, drip irrigation has revolutionized agriculture by targeting water right at the roots, reducing evaporation loss. With technological advances, modern drip irrigation systems have become automated, allowing you to precisely adjust watering times without constantly monitoring.
According to the FAO, drip irrigation can increase crop yields by up to 90% while also reducing water usage. Today, this technique is not only used in large-scale farms but also in urban gardens and small home cannabis setups—even for a single plant.
Types of drip irrigation
Wondering which drip irrigation system is best? There are several types, each suited to different growing needs and scales. Here are the most common ones:
Manual drip irrigation
This is the most basic and affordable type. It involves placing hoses or tubes with drippers directly at the plant roots. Watering is done manually by opening and closing valves after you’ve calculated how long to water. It’s ideal for small-scale grows or urban gardens. While simple, it requires more time and effort from the grower.
Automated drip irrigation
This system connects to a water source and uses a pump to distribute water in a controlled way. It’s ideal for medium to large grows, allowing you to program watering schedules and control water amounts without manual input. Some advanced models even offer remote control via smartphone apps.
Pressure-compensated drip irrigation
This system uses special emitters that deliver a consistent water flow regardless of pressure changes. It’s perfect for uneven terrain or setups where water pressure might fluctuate. It ensures all plants get the same amount of water, no matter their location.
Subsurface drip irrigation
Here, the drip lines are buried underground, close to the roots. This method is highly efficient because it reduces water loss through evaporation and directs water right where the roots absorb nutrients. It’s a great option for greenhouses and gardens seeking maximum efficiency.
Gravity-Fed drip irrigation
This setup uses gravity to move water from an elevated tank through the system—no pump needed. Kits like AutoPot are simple and budget-friendly. It’s perfect for small home grows as it requires no electricity and is easy to install.
Inline drip irrigation
This system uses hoses with built-in emitters spaced evenly along the line. It allows you to water multiple plants at once, making it efficient for rows of cannabis plants. It ensures uniform watering across the entire grow area.
Low-flow drip irrigation
This system uses emitters that release very small amounts of water, perfect for plants that require minimal moisture or for dry climates. It’s commonly used for indoor grows or areas where water is scarce.
How to calculate drip irrigation
Knowing how to calculate drip irrigation time is key to ensuring your cannabis plants receive the right amount of water—no more, no less. The efficiency of the system depends on climate, substrate type, and the plant’s growth stage.
Watering frequency is not universal; multiple factors influence it. Here’s how to determine the correct frequency and duration:
- Substrate type. Lightweight substrates like coco coir or perlite drain quickly, so you’ll need more frequent watering. Heavier soils retain moisture longer, allowing for less frequent watering.
- Growth stage. Cannabis plants need more water during the vegetative phase to support root and leaf growth. In the flowering stage, water needs decrease.
- Weather conditions. In hot or sunny climates, plants lose more water through evaporation, requiring more frequent watering. Cooler climates mean less frequent irrigation.
- Number of plants and grow size. A small grow with one or two plants won’t need watering as often as a large-scale grow. Home drip systems are simpler but still effective.
Formulas & methods for calculating drip irrigation time
Learning how to calculate drip irrigation time helps you give your plants the right amount of water without wasting it. Here are several useful methods:
Substrate volume method
- Pot or grow bed volume. Measure length × width × height.
- Water retention capacity. Different substrates hold different amounts of water. Coco retains more than sandy soil.
- Watering amount. Apply 10–20% of the total substrate volume. For a 10-liter pot, apply 1–2 liters of water.
- Watering interval. If your substrate stays moist for 2–3 days, that’s your watering frequency. Water more often during hot weather or rapid growth phases.
Evapotranspiration (ET) method
- ETc (Crop Evapotranspiration). Represents the water your plants need based on weather conditions.
- ETo (Reference Evapotranspiration). A standard value based on climate data like temperature and sunlight.
- Kc (Crop Coefficient). Adjusts ETc depending on the plant’s growth stage.
The formula is ETc = ETo × Kc. You can calculate the daily water requirement in millimeters. Multiply by the grow area to convert to liters.
The “Finger Test”
A simple manual method for small grows:
- Insert your finger 3–5 cm into the soil.
- If it feels dry, it’s time to water. If moist, wait.
- It’s not exact, but useful for home growers.
Automatic drip systems with sensors
Automatic systems use moisture sensors to detect when plants need water. Although more expensive, they’re very efficient. Some include timers and controllers for detailed scheduling—even via smartphone apps.
Adjusting by Season
- Spring: Water every 2–3 days.
- Summer: Daily watering or twice daily in extreme heat.
- Fall: Every 4–5 days depending on climate.
- Winter: Water less; plants need less moisture.
Final calculation of drip irrigation time
- Emitter flow rate. Standard drippers deliver 2 to 4 liters per hour (L/h).
- Watering time. If a plant needs 2 liters and your emitter is 2 L/h, water for 1 hour.
To make things even easier, use the table below as a quick guide for how to calculate drip irrigation time based on your growing conditions.ç
| Factor/Condition | Required Calculation | Watering Frequency |
|---|---|---|
| Substrate Volume | Substrate volume × 0.1 (10% of total volume) | Apply 10%-20% of the total substrate volume per watering. If the pot is 10L, apply 1-2L of water. Water every 2-3 days in summer and less frequently in winter. |
| Finger Test | Insert your finger 3-5 cm into the substrate. If the soil feels dry, it’s time to water. |
Water only when the finger comes out dry, depending on substrate moisture. Typically every 2-3 days or according to climate. |
| Temperature & Season |
Spring: 2-3 days between waterings. Summer: Daily or twice a day. Autumn: 4-5 days between waterings. |
Adjust frequency according to the season. More frequent in summer (daily), less in autumn (every 4-5 days). |
| Dripper Flow Rate | Dripper flow rate (L/h) × Time (h) If drippers deliver 2L/h and 2L is needed, watering time is 1h. |
Adjust watering time based on dripper flow rate. For example, a 2L/h dripper will deliver 2L in 1 hour. |
| Automatic Systems (Sensors) | Automatic watering: According to moisture measured by sensors. Sensors activate watering when moisture is low. |
Sensors trigger watering when the soil is dry. This depends on pre-set system values. |
| Evapotranspiration (ETc) | ETc = ETo × Kc Calculates the water needed by the plant considering climate, crop coefficient, and environmental conditions. |
Depends on ETc value. In hot or dry climates, frequency can be daily. In cool climates, every 3-5 days. |
How to calculate the flow rate of a faucet:
To calculate the flow rate of your faucet or hose, you can use a simple method based on time and water volume.
- Use a bucket of known capacity (e.g., 10 liters) or a decanter with measuring marks.
- Turn on the faucet or hose completely.
- Time how long it takes to fill the container.
- Apply the flow rate formula: Flow rate (L/min) = Volume of water (L) ÷ Time (seconds) × 60
Quick reference table: How to calculate drip irrigation time
| Plant Size | Emitter Flow Rate | Water Needed per Watering | Irrigation Time |
| Small (1–3L pot) | 2 L/h | 0.5–1 L | 15–30 minutes |
| Medium (5–10L pot) | 2–4 L/h | 1–2 L | 30 minutes – 1 hour |
| Large (20L+ pot) | 4 L/h | 2–4 L | 1–1.5 hours |
| Outdoor Garden | Varies | Depends on weather/substrate | Use ET method or sensors |
Watering tables according to soil type in each season
How to calculate drip irrigation time according to soil type? Soil types (clay, sandy, gravelly, gravelly and loam) are distributed in different geographical areas according to factors such as climate, geology, topography and human activity. If you are going to plant in the ground, it is important to know what type of soil there is in our area, even if we are going to add some substrate. Here we leave you the drip irrigation tables perfectly detailed.
Clayey
Retains a lot of water, so it requires less frequent irrigation but longer duration.
| Substrate | Season | Frequency (days) | Irrigation Time (min) |
|---|---|---|---|
| Potting soil | Spring | 3-5 | 20-30 |
| Coconut coir | Spring | 4-6 | 15-25 |
| Perlite/Vermiculite | Spring | 5-7 | 10-20 |
| Potting soil | Summer | 2-3 | 30-45 |
| Coconut coir | Summer | 3-4 | 25-35 |
| Perlite/Vermiculite | Summer | 4-5 | 20-30 |
| Potting soil | Fall | 4-6 | 20-30 |
| Coconut coir | Fall | 5-7 | 15-25 |
| Perlite/Vermiculite | Fall | 6-8 | 10-20 |
| Potting soil | Winter | 7-10 | 15-25 |
| Coconut coir | Winter | 8-12 | 10-20 |
| Perlite/Vermiculite | Winter | 9-14 | 5-15 |
Sandy
Drains quickly, needing more frequent and shorter irrigations.
| Substrate | Season | Frequency (days) | Watering Time (min) |
|---|---|---|---|
| Potting soil | Spring | 1-2 | 20-30 |
| Coconut coir | Spring | 1-2 | 15-25 |
| Perlite/Vermiculite | Spring | 1-2 | 10-20 |
| Potting soil | Summer | 1 | 30-45 |
| Coconut coir | Summer | 1 | 25-35 |
| Perlite/Vermiculite | Summer | 1 | 20-30 |
| Potting soil | Fall | 2-3 | 20-30 |
| Coconut coir | Fall | 2-3 | 15-25 |
| Perlite/Vermiculite | Fall | 2-3 | 10-20 |
| Potting soil | Winter | 3-4 | 15-25 |
| Coconut coir | Winter | 3-4 | 10-20 |
| Perlite/Vermiculite | Winter | 3-4 | 5-15 |
Gravelly
Similar to sandy, but with better drainage.
| Substrate | Season | Frequency (days) | Watering Time (min) |
|---|---|---|---|
| Potting soil | Spring | 2-3 | 25-35 |
| Coconut coir | Spring | 2-3 | 20-30 |
| Perlite/Vermiculite | Spring | 2-3 | 15-25 |
| Potting soil | Summer | 1-2 | 35-50 |
| Coconut coir | Summer | 1-2 | 30-40 |
| Perlite/Vermiculite | Summer | 1-2 | 25-35 |
| Potting soil | Fall | 3-4 | 25-35 |
| Coconut coir | Fall | 3-4 | 20-30 |
| Perlite/Vermiculite | Fall | 3-4 | 15-25 |
| Potting soil | Winter | 4-6 | 20-30 |
| Coconut coir | Winter | 4-6 | 15-25 |
| Perlite/Vermiculite | Winter | 4-6 | 10-20 |
Franco
Balanced, retains water well but also drains well.
| Substrate | Season | Frequency (days) | Watering Time (min) |
|---|---|---|---|
| Potting soil | Spring | 2-4 | 20-30 |
| Coconut coir | Spring | 3-5 | 15-25 |
| Perlite/Vermiculite | Spring | 4-6 | 10-20 |
| Potting soil | Summer | 1-2 | 30-45 |
| Coconut coir | Summer | 2-3 | 25-35 |
| Perlite/Vermiculite | Summer | 3-4 | 20-30 |
| Potting soil | Fall | 3-5 | 20-30 |
| Coconut coir | Fall | 4-6 | 15-25 |
| Perlite/Vermiculite | Fall | 5-7 | 10-20 |
| Potting soil | Winter | 5-8 | 15-25 |
| Coconut coir | Winter | 6-9 | 10-20 |
| Perlite/Vermiculite | Winter | 7-10 | 5-15 |
Drip irrigation is not only an efficient technique; it is a smart and sustainable solution for any cannabis grower looking to maximize the yield of their plants while caring for the environment. With this system, you’ll not only save water and time, but you’ll also ensure that your plants receive the exact amount of water and nutrients they need at every stage of their growth.
Now that you know how to time your drip irrigation, it’s time to take the plunge and switch to this technology. Use the guide we’ve provided to adjust your irrigation to the specific needs of your crop and watch your plants grow healthier and more productive.
