Rosemary is an iconic drought-tolerant herb that is as beautiful as fragrant. In hardiness zones 7-11, rosemary is a reliable perennial that doesn’t need much to thrive.
This plant doesn’t mind poor soils, low fertility, and drought. However, it is a bit pickier about sunlight.
If you’re trying to figure out where to plant rosemary in your garden, here is everything you need to know about its light preferences.
The Quick Answer
Rosemary is a Mediterranean native that loves vibrant sunshine and warmth. You should plant it in an area with at least 6 hours of direct sunlight daily and very well-drained low-fertility soil. This perennial shrub needs plenty of light to fuel its growth. Although rosemary can tolerate some shade, it will not thrive there. Rosemary grows more slowly in shady conditions and may even die from a lack of sunshine.
The Detailed Answer
Rosemary needs at least 6 hours of direct sunlight daily and well-drained low-fertility soil.
Rosemary is a sun-loving Mediterranean native that thrives in rocky gardens alongside lavender, thyme, and sage. It cannot grow to its full potential without direct sunshine. We talk about this in the video below around 1:19 in.
Check out the above video at around 1:19 where we discuss planting requirements.
It is important to keep rosemary in an area where it won’t get shaded out by trees or structures. The plant can also be grown indoors in a container if it receives bright, direct light from a south-facing window. Only in ultra-hot southern climates should you consider giving rosemary some slight shade.
Let’s dig into why rosemary needs so much sun and how to ensure it gets enough of the light it craves.
Sunlight and Fragrance
More exposure to sunlight results in a stronger flavor.
The earthy, sage-like aroma of rosemary comes from the plant’s volatile essential oils (terpenes). These oils form in leaf structures called trichomes. Plants naturally produce more trichomes when they have more light. Basically, more sunshine means a stronger-smelling rosemary shrub!
This study found that rosemary produces its delicious-smelling essential oils to help protect itself from UV damage and deter pests from eating the leaves.
This means rosemary naturally produces more fragrant oils when exposed to the highest light levels possible. Rosemary’s protective oils explain why the plant can survive the intense summer sunshine on exposed slopes of the Mediterranean Sea.
The only caveat here is that the plant produces less volatile oils in extreme heat. Rosemary can lose its fragrance at ultra-high temperatures consistently above 95°F. This is why planting in the cool, dappled shade is only recommended in the hottest southern climates.
When Rosemary Doesn’t Get Enough Sunlight
Rosemary needs a minimum of 6-8 hours of UV light per day to maintain its vigor, fragrance, and appearance.
The happiest rosemary shrubs bask in full sunlight for the entire day. When rosemary doesn’t get enough light, it will lack vigor and fragrance. In overbearing shade, the plant can die altogether.
The most notable signs that your rosemary needs more light include the following:
|Low Vigor and Stunting||Like all plants, rosemary needs light to perform photosynthesis. Photosynthesis is how the shrub produces the energy and sugars it needs to grow. Rosemary can grow up to 4 feet tall and wide, but in low light, the plant often stays small and pathetic. Stunted growth is a sure sign that your rosemary isn’t getting enough sunshine.|
|Lack of Fragrance||Most people grow rosemary for its delicious fragrance and flavor, but the plant quickly loses its signature smell when it doesn’t get enough sunshine. A minimum of 6-8 hours of UV light per day ensures the most aromatic rosemary possible. Other reasons for low fragrance include too much fertilizer or too much water.|
|Pale or Yellowing Leaves||Rosemary plants are known for their deep evergreen color. This rich hue comes from a strong chlorophyll concentration in the rosemary needles. When the plant doesn’t get enough sun, it struggles to produce chlorophyll which leads to an overall pale or yellow appearance. Yellowing can also be caused by over-watering or over-fertilizing.|
|Leggy Growth||When rosemary plants start producing thin, floppy stems, it’s a sign that they are reaching toward the sun. This is especially common in container-grown rosemary plants during the winter. Regular pruning can help band-aid this issue, but it won’t resolve the root cause of low light.|
Fixing Light Deficiency
Transplanting a rosemary plant to a brighter location can save the plant, allowing it to recover in a few weeks.
If you have a sad rosemary plant that needs more light, you don’t have to throw it away and start over! These resilient herbs willingly transplant to new locations and can perk back up in no time. When you transplant your rosemary to a brighter area, it’s also a great opportunity to fix any soil or water issues the plant has.
Save your dying rosemary plant by transplanting it:
- Use a shovel to dig around the circumference of the plant’s root ball.
- Make sure you don’t damage the roots.
- Create a circle about 1 foot from the base of the rosemary’s stem.
- Gently lift the plant from the ground (or container).
- Place it on a tarp while you prepare a new planting area.
- Don’t leave the bare roots exposed to the sunlight for too long.
- Move the rosemary to an area that receives at least 6-8 hours of daily sun.
- If the soil is waterlogged or high in clay, amend it with sand or vermiculite.
- Dig a hole about 1.5 times the size of the root ball.
- Lower your rosemary plant into the new hole.
- Backfill so that no roots are exposed to the surface.
- Ensure that you don’t mound any soil up on the base of the stem.
- Place a thin piece of row cover over the rosemary bush.
- This will help allow it to adjust to brighter light.
- Remove the row cover after a week.
- Provide generous watering once or twice a week until the plant acclimates.
- It may look yellow or transplant-shocked at first.
- The plant should recover within 2-3 weeks under its sunnier new conditions.
In Northern Climates, Provide Maximum Sun
Plant rosemary in open, sunny areas away from shadows to ensure its healthy growth in northern regions.
Rosemary is a tender perennial but still survives in many northern gardens. Because of the winter sun’s angle in the north, it is especially important to plant rosemary in a wide open area. Shade from trees, large shrubs, or your house can dramatically reduce rosemary’s growth potential.
If you live in a rainy area like the Pacific Northwest, full exposure to sunlight is even more critical for rosemary survival through the winter.
Choose the southernmost-facing area where the shrub won’t suffer beneath any shadows. Planting rosemary in an open site will save you many headaches later because it also reduces the risk of foliar disease.
In Southern Climates, Provide Afternoon Shade
Rosemary thrives in hot and dry climates but may benefit from dappled afternoon shade in hardiness zones 10-11.
The only climate where we recommend providing rosemary with shade is in hardiness zones 10 and 11. Rosemary doesn’t mind the hot summer sun but appreciates some afternoon shade in areas like the Southwest and Southeast.
Dappled afternoon shade will ensure that the plant is not scorched by intense desert or tropical summers. This herb is surprisingly rugged in the heat and drought of these areas. However, it appreciates a shady respite in the hottest regions. This will ensure that your rosemary still smells and looks great in the garden.
Can Rosemary Grow in Low Light?
Rosemary can tolerate partial shade with 4-6 hours of direct sunlight, but it grows slower.
While rosemary will grow slower in the shade, it does tolerate lower light areas with 4-6 hours of direct sunlight. In northern climates, dappled or partial shade can reduce rosemary’s fragrance and vigor.
But in the hottest climates like the Southwestern or Southeastern United States, rosemary often enjoys protection from harsh sunlight and heat.
Rosemary is a remarkably rugged plant, but it will suffer in low-light conditions. If you give rosemary the sunshine and well-drained soil it craves, it will produce aromatic leaves and flowers for years to come.