Whether you’re new to gardening or have been growing plants for decades, you already know that each plant has its own light requirements.
The sensitivity of each plant to light is determined by many factors, including its place of origin and the environmental circumstances it has adapted to.
Before we discuss the light requirements for herbs, I should first perhaps clarify that this is a very wide topic. There’s a lot of division between herbs concerning light sensitivity.
Don’t be troubled though. In this article, we will go through the most important elements regarding herbs and light, and in the end, we will talk about some specific cases of herbs and their light requirements.
The Basics of Light Requirements for Herbs:
Every plant requires a certain amount of light per day to function normally. We usually don’t talk about an “amount of light” that a plant gets; instead, we measure the number of hours of light it is exposed to.
Amount of Light: Full Sun, Partial Sun, and Full Shade
Full sun, partial sun, and full shade are the terms you should focus on the most. When we want to categorize herbs according to their light needs, we often use these words.
From the name, full sun indicates that the herb needs long periods of light exposure. Full-sun herbs need a minimum of six to eight hours of direct sunlight per day.
There is a wide variety of full-sun herbs that includes sage, rosemary, and dill. Most of these plants are native to temperate and tropical regions where the sun shines intensely during the day.
Plants that need four to six hours of direct sunlight exposure per day are said to be partial sun, and those that need less than four hours of sun are considered to be partial or full shade.
It should be noted that these concepts aren’t strict and are used flexibly by gardeners. In fact, experts created these terms for the sake of making gardening easier for everyone and not to explain light needs for plants.
Each herb can fall into one, two, or all of the above categories. In other words, a particular herb species may have the ability to flourish in both full sun and partial sun.
Other varieties of herbs, for example, may be able to survive on four hours of sunlight exposure per day but prefer six to eight hours instead.
Lemon balm, for instance, can stay alive in partial sun to full sun but flourishes best when given at least six hours of sunlight per day.
To sum up, most plants are really flexible concerning how much light they need, but you should make sure that you’re getting the highest quality of herbs. For this reason, you should be looking at the optimal light requirements of each herb and not just its light tolerance.
Another important point that is usually overlooked by herb gardeners is photoperiod. This is particularly significant when you’re growing your herbs indoors under artificial light.
Photoperiod generally indicates the sensitivity of plants toward the difference between day and night. It is an advanced way for them to detect the change in seasons.
For example, in the spring, days get longer and nights become shorter (in the Northern Hemisphere). Some herbs that love warm weather will take advantage of this natural indicator to know when spring would arrive.
Overall, when herbs feel they’re getting longer or sometimes shorter periods of sunlight exposure (direct or indirect), they will move into the flowering phase.
With basil, mint, and other leafy herbs, this is troubling. Plants tend to end their life cycle when they finish their flowering phase. They also become stiffer and less flavorful.
If you’re growing your herbs under unregulated conditions, it’s very hard to control this aspect of their growth. In this case, the best thing you can do is to wait for them to flower and then pinch off their buds.
On the other hand, growing herbs under artificial light would allow you to control your plants’ photoperiod, preventing them from blooming.
Practically, photoperiod is less important than the total amount of light your plants are getting. In the end, this doesn’t affect your herbs’ survival chances at all.
What Could Possibly Go Wrong?
So, where do gardeners usually make mistakes when serving the light requirements of herbs?
Too Little Light:
Too little light is fatal for plants. If your full-sun plants are getting only four hours of direct sunlight per day, their leaves will start to turn yellow.
When your plant stops getting the ideal amount of light, it won’t be able to produce the needed quantity of food. Lack of food for the plant means eventual weakness and probable death.
Many of the problems that gardeners face are due to lack of light, so don’t hesitate to give your herbs the amount of light they need and deserve.
Too Much Heat:
Plants can’t die from too much light, but they can from too much heat. Sunlight doesn’t consist of just bright intense light but also heavy heat waves. Although plants need some warmth, they can be really disturbed by high-temperature light, especially for those that prefer shade and partial sun.
During the day, the sun’s heat gradually increases until sometime before sunset. In other words, the afternoon sun is much hotter than the morning sun.
Herbs that get excessive amounts of “warm” sunlight will become more prone to dehydration and start to wilt. Then their leaves will gradually curl, turn yellow, and fall off.
That’s why gardening experts always advise people to expose their plants more to morning sun than afternoon sun.
Ideally, put your herbs where they can face the morning sun, starting from when it rises until afternoon. You can also buy some LED or fluorescent grow lamps to prevent your herbs from receiving a lot of heat during the day.
Popular Herbs and Their Light Requirements:
Full Sun Herbs:
- Cilantro (Coriander): This herb can grow in full sun as well as partial and full shade, but it grows best with at least six hours of sunlight exposure per day. If the weather is too hot, however, avoid exposing it to afternoon sun.
- Echinacea: Being a heavy-flowering plant, it’s not odd to find that echinacea loves the full sun.
- Borage: This is also a flexible plant that tolerates partial sun but prefers to grow in full sun.
- Fennel: This is an exclusively full-sun plant. Fennel should get at least six hours of sun per day.
- Sage: This herb is known to be a sun-loving plant that tolerates drought rather well.
You can learn more about full sun herbs here!
Partial Sun Herbs:
- Parsley: This plant grows in partial to full sun. It’s preferable to grow it in partial sun if the weather isn’t tolerant in your area.
- Mint: Mint can also grow in both full and partial sun, but I prefer to expose this plant to the sun only in the morning.
- Monarda (Bee Balm): Bee balm is a plant that grows best in partial sun, although it’s very flexible with light.
- Chervil: This plant cannot tolerate full sun in summer, so it’s usually grown in partial sun.
- Lovage: This herb can grow very tall if it is given the amount of light it needs. It can tolerate partial to full sun.
You can learn more about partial sun herbs here!
Full or Partial Shade Herbs:
- Goldenseal: This herb grows naturally in the woods under trees, so it prefers full shade.
Discover how to grow goldenseal here!
- Gotu kola: This plant is more flexible with light than goldenseal, but it grows naturally in shady conditions.
- Ginger: This plant can tolerate all amounts of sunlight but grows best when given between 2 to 4 hours of direct sunlight per day.