Herbs are flavorful, fast, and easy to grow – making them a staple in the indoor and outdoor kitchen garden. Herbs need a fair amount of sunlight - most prefer what we'd call a full sun location. That explains why many herbs just don't thrive when grown indoors...there's just not enough light!. In this blog, we’ll review the light needs for the different herbs, how to see if you have enough natural light, and how to set up a simple but effective grow light.
Light Needs for Herbs
Light drives photosynthesis, which in turn provides the energy for all plant functions. Without enough light your herbs simply won't be able to make enough energy to grow and thrive. And did you know? Light quantity and quality also plays a big part in herb flavor. That's right, light stimulates the production of the essentials oils and flavonoids that give herbs distinct flavor and aroma. When grown under too little light, flavor aroma is often less intense.
But, more importantly, you can't keep harvesting herbs that aren't growing! So, giving your herbs adequate light indoors is a must.
The minimum and ideal hours of direct sunlight for the culinary herbs are:
Generally, 6 to 7 hours of sunshine hitting the leaves will provide all herbs with enough light to grow well. However, 6 hours is a lot of direct light to get in any window, so depending on your conditions you might want to look at the lower light herbs (like mint or parsley). While it’s a must to hit the minimum, you’ll get faster growth as you give the plant more light. If you want more herbs, the #1 thing you can do is give your plant more light.
Do I have enough sunlight to grow herbs?
Even if a window in hour home seems "bright", it may not actually provide enough light for growing herbs. We find that most windows benefit from supplemental grow lights.
Season & Window Direction
Every home will be different when it comes to exposure and light levels. Generally speaking, south-facing windows typically offer the most natural light, and thus your best chance for growing indoors with only natural light; though you will need to understand some seasonal shifts. In the fall and spring, bright, unobstructed southern windows work well for growing herbs. In the winter, your southern window is still your best bet, but the weaker sunlight might need to be combined with a grow light. In the summer, southern windows can get very hot so you might find you need to pull herb plant back a bit from the window...or you might find your sun-loving herbs do just fine in a southern window in summer!
Have a bright window? Give our handy window shelf a try!
Watch your plants
The ultimate test of your natural light will be your plant’s growth...or lack thereof. You can tell very early if you don't have enough light – you’ll notice your herbs start to look leggy and stretched. Plus, overall growth will slow down or may stop. If your herbs respond this way, it's time to add a grow light!
Setting up a grow light for year-round, fast-growing herbs
Grow lights can be a little intimidating – but they really shouldn’t be! There is a lot of marketing noise to cut through, but at the end of the day, a well designed grow light provides a 1:1 replacement for sunlight, looks nice in your home, and pays for itself. Plants love the consistency of grow lights, which helps your little space be as productive as possible.
The easiest types of grow lights to use are full spectrum LED spotlights with an E26/27 base, in the 20-40 Watt range. These "bulbs" can be inserted into most home fixtures, such as the Vita LED Grow Light:
Or you can choose an integrated fixture, such as the SolTech Aspect LED:
How far: Depending on the strength of the grow light, position your LED spotlight anywhere from 6- to 18-inches above your herbs. The closer your grow light is to the plant the more intense the light delivery (PPFD), but will also increase the temperature as well.
How long: If you're growing in a southern window, you may only need to run your grow light for 4-6 hours to supplement enough light. If you are not growing in a spot with much natural light, you may run your lamp/s for 10-12 hours to provide enough light for your herbs.
How many plants: Also, the closer your grow light is to your plants, the smaller the area the light will cover. So if you need to light a group of plants you may need to hang several grow lights to provide enough coverage for all your plants at a distance that still provides enough light. At a distance of 6- to 12-inches you're typically lighting one or two plants. At a distance of 12- to 24-inches you can light a group of 4-6 plants (approximately).
Your Herbs Will Tell You!
Different herbs will respond differently to light intensity and duration, so as always, watch your plants! They will tell you pretty quickly if light is too intense (yellowing and scorching on leaves), or too little light (pale leaves, leggy stretched slow growth).
Want to Level-Up Your Indoor Lighting Knowledge?
Read our primer for Grow Lights for Indoor Plants!