How to Water Cannabis Indoors and Outdoors? A Complete Guide for Beginners and Beyond

Does cannabis need water?

Cannabis is a fast-growing annual plant that requires constant access to water in the root zone. Due to its rapid growth, water demand is high, while the plant stores very little water internally.

Even short-term drought can quickly affect plant health, growth rate, and final yield.

What happens when cannabis is not watered?

Cannabis reacts very quickly to water deficiency. To survive and protect flowers, the plant starts pulling water from lower leaves first, then progressively from higher parts.

Affected leaves lose turgor, begin to droop and look lifeless. After several hours (depending on temperature and humidity), leaves turn yellow and die.

Before yellowing, leaves can still be saved. Simply restore water to the root zone. Foliar misting can speed up recovery.

Warning: never spray plants exposed to strong light or heat. Indoors, mist only when lights are off.

Can cannabis be overwatered?

In outdoor cultivation, overwatering plants growing directly in the ground is almost impossible. Roots have unlimited space and excess water drains naturally. Problems occur only after extreme rainfall and standing water.

Indoors, however, overwatering is one of the most common beginner mistakes. Potted plants have limited root space and poor drainage leads to root suffocation.

Symptoms of overwatering

Overwatered plants often develop root rot. Excess moisture promotes bacteria and fungal growth.

Root rot causes severe growth slowdown and yellowing leaves starting from the bottom.

Often mistaken for nutrient deficiencies!

This leads beginners to add fertilizers, increasing water volume and raising EC (salt buildup), making the situation worse.

How to recognize root rot caused by overwatering

1. Daily watering, even small amounts, causing water to stagnate at the pot bottom.
2. Stunted growth and pale leaves from bottom upwards.
3. After removing the plant, outer and bottom roots appear brown or yellow and smell rotten when crushed.

How to save an overwatered plant – step by step

Step 1: Carefully remove the plant from its pot.

Step 2: Prepare a larger pot with fresh, high-quality light-mix soil.

Step 3: Place the plant into the new pot. Do not remove old soil from the roots.

Step 4: Do not water immediately. Allow the medium to dry.

Step 5: Water only when the pot is nearly dry – this is the ideal moment.

Step 6: Weigh the pot when dry to learn watering timing by weight.

When should cannabis be watered?

There is no universal schedule. It depends on temperature, humidity, light intensity, ventilation, and humidifier use.

Most commonly every 2–5 days.

Water slowly, in stages, until runoff appears at the bottom.

Golden rule: water only when the pot is almost dry.

How to check if the pot is dry

• Finger test – simple but inaccurate.
• Pot weight – one of the best methods.
• Check drainage holes (dark = wet, light = dry).
• Fabric pots: feel the bottom through the side.

How much water does cannabis need?

• 1.5–2.5 L for 10–15 L pots
• 3–4 L for 15–30 L pots

Summary

Proper watering is one of the most important cultivation skills. Water less often but thoroughly. Most indoor problems come from overwatering, not underwatering.