Cannabis Guttation: Why Your Leaves Drip Water at Night

By Rick Smith / October 3, 2026

Cannabis leaflet with a single clear guttation droplet at the tip of each serration on an otherwise dry leaf

Table of Contents

Quick answer: Cannabis guttation is water that leaves push out through tiny pores called hydathodes at the leaf tips and edges. It happens mostly at night, when the leaf pores are closed but roots keep pushing water up, especially with wet soil, humid air and calm conditions. It is a normal pressure release, not a disease, though the drops can dry into a white mineral residue.

What Is Guttation?

Guttation is how plants release water from structures called hydathodes on the margins or tips of leaf blades. University of Missouri horticulturist Christopher Starbuck describes it as a pressure relief for plants. The hydathodes sit on leaf margins near the ends of tiny veins.

On a serrated leaf, Michigan State University says the drops form on the tips of the serrations on the edge of the leaf. Cannabis leaflets have toothed edges, so look for small beads at the points of the teeth and at each leaflet tip.

Photo-style illustration of clear water drops at the serration tips along the edges of a cannabis fan leaf in soft light

Is Cannabis Guttation Normal?

Yes. University of Missouri says that even though the water lost to guttation contains minerals and sugars, the losses are inconsequential. Michigan State University calls guttation not harmful to grapevines, and University of Maryland Extension says that in most cases no control measures are needed for the leaf edge symptoms it can leave behind.

Why Cannabis Leaves Drip Water at Night

During the day, a plant pulls most of its water from the soil through suction created by transpiration, which is evaporation from pores on the leaves. University of Missouri says over 90 percent of the water used by most temperate zone plants is lost to the air this way.

At night those pores close up. University of Missouri explains that under night time conditions of high humidity, cool air and warm soil, root pressure can still move water to the leaves. Since the pores are closed, transpiration cannot remove the water, so the hydathodes release droplets to relieve the pressure.

The e-GRO team at NC State and the University of Kentucky describes the same thing in greenhouse plants: water droplets can form overnight along the leaf margin due to excessive moisture and humidity. Indoors, the dark period is the plant’s night.

What Makes Guttation More Likely

Wet soil. Michigan State says guttation follows soil saturated with water.
Humid air. Both Missouri and Michigan State name high humidity.
Calm air. Michigan State says calm weather minimizes evaporation from leaf surfaces.
Cool air over warm soil. University of Missouri names this night time combination.

Our guide to relative humidity control for cannabis covers the humidity side.

Guttation, Dew and Edema Compared

Guttation drops are easy to mistake for dew, but they form in a regular pattern. University of Missouri describes them as tiny water droplets uniformly spaced around the margins of a leaf, and notes that people often wonder what would cause dew drops to form in such a regular pattern.

Sign	Guttation	Dew	Edema
Where the water comes from	Inside the plant, through hydathodes	Moisture from the air	Not a water drop
Where it shows	Leaf tips and edges, evenly spaced	All over the leaf surface	Tiny blisters on leaves
When	Night and early morning	Cool, clear nights	Long humid spells with wet soil
Concern	Usually none	None	A non infectious disorder

University of Missouri describes edema as a non infectious disorder in which tiny blisters appear on leaves during long periods of high humidity and excess soil moisture. It also notes that guttation may reduce the incidence of edema.

What Is in Guttation Drops?

University of Maryland Extension says guttation water often contains organic and inorganic compounds and mineral nutrients, especially potassium. As the water evaporates, these compounds are left behind and concentrated at the leaf margin. Michigan State University describes the same thing as salt deposits on the leaf margins.

UMD adds that over time the high concentration of compounds can show up as a marginal yellowing called salt burn. It links salt accumulation with foliar sprays of nutrient solutions during very hot, dry weather, and says soil applied urea or ammonium nitrate fertilizers may add to the problem. Our feeding schedule for cannabis in soil covers feeding in general.

How to Reduce Cannabis Guttation

You don’t actually have to stop it. If drops show up every morning and you’d like fewer, work on the conditions that cause them.

Water earlier in the day. That gives the mix time to dry back a little before lights off, so it is not saturated going into the night.
Check drainage. Make sure pots drain freely, since Michigan State links guttation to saturated soil.
Lower night humidity. Missouri and Michigan State both link guttation to humid air.
Keep air moving at night. Michigan State says calm conditions limit evaporation from leaves, so gentle airflow helps.
Avoid foliar feeding in hot, dry weather. UMD links salt accumulation at leaf edges to foliar nutrient sprays under those conditions.
Watch the leaf tips. Check for white residue or yellow edges after the drops dry.

If the mix stays wet for days, read our guide to overwatering and cannabis growth.

Troubleshooting

Drops on the leaf tips every morning. This is usually plain guttation. Missouri says the losses are inconsequential. If you want fewer drops, water earlier and lower night humidity.

White crust on leaf tips after the drops dry. UMD says the compounds in guttation water are left behind at the leaf margin as it evaporates. This residue is usually cosmetic. If a crust also forms on the soil surface, see our guide to salt buildup in cannabis soil.

Yellow leaf edges after weeks of drops. UMD calls this marginal yellowing salt burn. In most cases no control is needed, but UMD notes there could be losses if salt burn is severe and widespread.

Drops and a droopy plant. Guttation alone does not make a plant droop. If the plant also wilts and the mix stays soggy, check your watering and drainage.

Brown or crisp leaf tips with no drops. That points away from guttation. Tip burn can have other causes, so look at your feeding and growing conditions.

Odd angular leaf spots. The e-GRO team says angular leaf discoloration linked to guttation can be confused with other problems. Have unusual spots checked by your county Extension office or a plant diagnostic lab.

Frequently Asked Questions

What causes cannabis guttation at night?

Root pressure. University of Missouri says that on nights with high humidity, cool air and warm soil, roots can keep moving water up to the leaves. With the leaf pores closed at night, the water leaves through hydathodes as droplets. Michigan State University adds wet soil and calm weather to the list.

Is cannabis guttation the same as dew?

No. Guttation drops come from inside the plant, out of hydathodes on the margins or tips of leaves. University of Missouri describes them as tiny water droplets uniformly spaced around the margins of a leaf. Dew is moisture from the air that settles on the whole leaf surface.

What is the white residue left by cannabis guttation on leaf tips?

It is what the drops leave behind. University of Maryland Extension says guttation water often contains organic and inorganic compounds and mineral nutrients, especially potassium. As it evaporates, these compounds are concentrated at the leaf margin. Michigan State University calls them salt deposits.

Can cannabis guttation lead to plant disease?

Only in rare cases. University of Missouri says that in rare cases bacteria can grow in guttation droplets and be pulled back into the leaf when the sun comes up, leading to disease infection. For most plants, guttation is simply a pressure release.

Is cannabis guttation harmful to my plants?

Usually not. University of Missouri says the minerals and sugars lost with the water are inconsequential. University of Maryland Extension says that in most cases no control measures are needed, though losses are possible if salt burn at leaf edges is severe and widespread. Keep an eye on white residue and yellow tips.