---
description: Carbon dioxide has now been proven as the source of almost all of a plant's carbon. Enriched CO2 can greatly stimulate plant growth.
title: Carbon Dioxide and Better Indoor Harvests - Part 1
image: https://www.questclimate.com/wp-content/uploads/2015/06/CO2_molec_sm.jpg
---

# Carbon Dioxide and Better Indoor Harvests

## Part 1

Most of us think of carbon dioxide (CO2) as “bad,” thanks to today’s news of global warming, but without CO2, plants wouldn’t thrive. In this article, we’ll talk about CO2 in general terms: Why plants need it, and why it is such an important element in getting hardier, healthier plants and better harvests.

### **Carbon dioxide and plant growth cycles**

Plants have controlled the carbon cycle for nearly 400 million years on land; they do this by using photosynthesis to convert CO2 from the atmosphere into the molecules that plants need for energy and growth. Humans and animals breathe oxygen, exhale carbon dioxide, and give plants what they need to thrive; the cycle continues as plants breathe carbon dioxide and exhale oxygen, giving us and the animals what we need to thrive.

### **The photosynthesis cycle in the grow room**

This same process occurs in the grow room. Plants use carbon dioxide, light, water and nutrients to make glucose and other molecules; they depend on glucose for the energy to grow. In turn, they expel oxygen. However, a recent discovery proves that carbon dioxide may be the greatest of all of these factors when it comes to plant health and growth. Why?

### **Flowering plants need CO2 for best growth**

The dry matter in most plants is comprised of 90% carbon, hydrogen, and oxygen. Almost all of that matter has now been proven to come from carbon dioxide. That means that CO2 is \*the\* most important ingredient for growth since it provides the carbon needed for the plant to live and grow. In general, you should use CO2 during the day from the seedling phase through the harvest.

### **Achieving the right balance: Photosynthesis during the day, respiration at night**

CO2 is essential for plant growth during the day, but the process reverses at night. Then, plants take in oxygen, just as humans and other animals do, and exhale carbon dioxide.

In the [next article](https://www.questclimate.com/carbon-dioxide-and-better-indoor-harvests-2/), we’ll talk about how to supplement CO2 during the day for better plant growth and harvests.

Published on Jun 16 2015 

Last Updated on Jun 05 2026 

Categories: [Agriculture](https://www.questclimate.com/category/industries/agriculture/), [High Plant Yield](https://www.questclimate.com/category/high-plant-yield/) 

Tags: [adding carbon dioxide](https://www.questclimate.com/tag/adding-carbon-dioxide/), [enriched CO2](https://www.questclimate.com/tag/enriched-co2/), [high CO2](https://www.questclimate.com/tag/high-co2/) 

Older Post [ Carbon Dioxide and Better Indoor Harvests – Part 2 ](https://www.questclimate.com/carbon-dioxide-and-better-indoor-harvests-2/) 

Newer Post [ Control Humidity to Best Fight Powdery Mildew ](https://www.questclimate.com/control-humidity-to-best-fight-powdery-mildew/) 

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