How to Control Humidity in a Greenhouse

Lead Image
  • 2-4 hours
  • Beginner
  • 50-100
What You'll Need
Anti-drip lining
Horizontal air flow fans
Combination thermometer and humidity gage
Shade cloth

One of the challenges that come if you own a greenhouse is how to control humidity. Greenhouses are an extremely useful feature for ardent gardeners. They’re made largely of glass or acrylic panels with a transparent roof. They are also commonly referred to as glasshouses.

They allow you to grow flowers, fruits, and vegetables all through the year. This is enabled by a special light, temperature, and humidity control in the building. If they are not properly regulated, these aspects create a less conducive environment for your plant life. For most plants, the ideal humidity lies between 50 percent and 60 percent. High humidity encourages mold and fungus growth while low humidity causes dehydration. Below is a useful guide to help you control humidity in your glasshouse.

Step 1 - Water

Do not apply excessive water to your greenhouse plants. Too much water creates puddles which increase the humidity when the water evaporates. Apply water to the soil rather than directly onto the leaves, flowers, and fruits to reduce on evaporation. Water your greenhouse plants in the early morning. This gives the soil several hours during the day for water to dry before nighttime temperatures fall.

Step 2 - Install Anti-Drip Lining

A close up on a greenhouse.

Condensation is common in some greenhouse designs. However, unchecked dripping contributes to higher humidity. Inspect your greenhouse for water drips. Attach anti-drip lining in the identified areas. You may also want to move plants that are in the drip line to an alternative location within the greenhouse.

Step 3 - Ventilate

Install horizontal air flow fans in your greenhouse. These improve circulation of air and help to expel humid air out. You may also want to install vents around your greenhouse. However, during the winter you need to take measures to control both the humidity and heat. The fans and vents cause temperatures to fall. This can result in condensation because the plants become colder than the air around them. It becomes necessary to increase the greenhouse temperatures for a proper balance. Obtain a combination thermometer and humidity gauge from a garden supply store. This will help you to monitor and regulate humidity levels more effectively. You may want to install a heating element during the winter. This can be obtained from your greenhouse supplier. It is installed at the bottom of the greenhouse and helps to heat the air within.

Step 4 - Clear Weeds

A greenhouse.

Regularly inspect your greenhouse for weeds. Clear weeds as soon as you spot them. Once plants absorb water some ends up on the surfaces of the leaves where it eventually evaporates. This contributes to higher humidity. Weed clearance helps to contain humidity levels.

Step 5 - Install a Shade

A shade is especially helpful during the summer when your greenhouse is likely to overheat. Obtain a shade cloth from a garden supply store. You can drape it over the top of your greenhouse to reduce temperatures within.