How Much Natural Light Does My Greenhouse Need?
Understanding how vegetables grow in our tropical climate conditions is the key to unlocking crunchy, sweet, non-bitter, nutritious and fresh produce grown in greenhouses. While most novice hydroponics growers focus on the nutrient solution only, the more experienced growers among us understand the total relationship between the grow environment and production yields.
Too Much or Too Little Sun
Our tropical sun puts out more than 100K lumens on a clear blue sky, but brings along a scorching UV index of 9-12 all year long. This means hot temperatures and high heat transfer onto objects, including our plants! All plants need light but can not stand too much surface heat – otherwise risking wilting, bolting, causing bitterness, or underdeveloped leaves and fruits.
For example, leafy lettuce seemingly looks good on all the pictures posted on Facebook/Instagram, but chances are that they taste very bitter and lack the consistency characteristics needed for restaurant quality produce.
While the initial reaction is to provide a shade canopy over the plants, too much shade can cause certain seedlings to run “leggy” in search for a light source upon germination. Plants grown in too much shade will turn out underdeveloped and will negatively impact the resulting production yields. The key to success is to understand how much light is actually needed from our sun.
Light Restriction vs Light Diffusion
Light restriction means limiting the amount of natural sunlight from entering your grow space. At the right light restriction ratio, your plants will feel comfortable and you’ll notice healthy, deep-green, wide and thick foliage. Light Diffusion means scattered light coming from all different directions rather than just from the direct source.
To get good uniformed growth, plants prefer to be in a grow space without heat and light stress. That’s why proper light restriction and light diffusion are very important to achieve good results.
Shade Screens or Shade Nets are used in greenhouses to achieve both light restriction and light diffusion. While most growers merely think of shade nets as a way of cooling down the temperatures inside the greenhouse, its function goes beyond reducing temperatures. There are a variety of shade screens or shade nets made of different materials and various shade percentage ratings.
What Type of Shade Screen Should I Get?
In our Bale Verde Urban Rooftop Smart Greenhouse, we found great results while using 70% aluminum shade screens instead of using black or green shade nets. The reflective silver material bounced the direct sunlight away thereby drastically reducing temperatures while letting in enough diffused light to make our plants happy. In combination with the shading created by the roofing layer of 8 mil UV film, the light level inside our greenhouse maxes out at 12K lumens during high afternoons.