My Rosemary is Dying: 10+ Reasons Why

“My rosemary is dying. What can I do?” We have here a list of problems for you to scan through. 

Rosemary is one effortless plant to keep. But you can’t escape instances of it struggling out of the blue
Rosemary is one effortless plant to keep. But you can’t escape instances of it struggling out of the blue

Rosemary is a fantastic herb to cultivate (and use as a spice).

However, it can sometimes wither away easily due to various reasons.

Even if you’ve showered it with sunlight, water, and affection, your rosemary might still unexpectedly turn brown and die. Yes, it’s disheartening.

The silver lining is that the plant doesn’t always have to succumb to this fate.

There are culprits you can catch in the act and, from there, rescue your beloved herb. Continue reading to uncover the secrets.

Root Rot

Let’s check out the most common reasons behind an abnormally ailing rosemary plant
Let’s check out the most common reasons behind an abnormally ailing rosemary plant!

Root rot is perhaps the most common problem affecting Mediterranean herbs such as rosemary and lavender.

When I first grew the herb in my garden, I encountered this issue too.

Rosemary with root rot tends to look somewhat wilted or drooping with foliage that turns brown, yellow, or black or has a dried and brittle appearance. 

To prevent root rot, ensure that your rosemary is planted in well-draining soil.

Consider adding sand or perlite to the soil mix, especially if you’re growing rosemary in containers.

Adequate drainage is essential for preventing excessive moisture around the roots.

If your plant doesn’t bounce back after transplanting, you may need to start over or address the potential issues described below.

1. Overwatering

1. Overwatering: This is perhaps the most common mistake, since rosemary likes dry soil
1. Overwatering: This is perhaps the most common mistake, since rosemary likes dry soil

Unlike your vegetable garden, rosemary doesn’t demand as much water.

These Mediterranean plants are accustomed to a dry summer climate with extended periods of drought throughout the growing season.

In truth, rosemary thrives in dry conditions and may voice its discontent if subjected to overwatering.

When growing rosemary in a container, it’s advisable to treat it more like a pothos plant or even a cactus.

Once your rosemary is all settled and cozy, you don’t have to shower it every day.

If it’s chillin’ in the ground, give it a little drink every 1.5 to 2 weeks. If it’s living the potted life, just water it once a week.

Usually, you only need to water it once every 1.5 - 2 weeks. This schedule may fluctuate in different climates
Usually, you only need to water it once every 1.5 – 2 weeks. This schedule may change in different climates

Of course this schedule will fluctuate in different climates, so I recommend you to take the principle by a grain of salt only. 

Instead, note that rosemary enjoys moderately dry but not completely devoid of moisture soil.

One easy (and instant) way to check the soil is simply poking your finger into it.

If the soil sticks to your finger, hold off on watering for a few days.

Make sure the top layers of soil feel dry before you think about giving your plant a drink.

If you’re growing in a container, you can also check the drainage hole. The soil may appear pale, dusty, or chalky.

2. Underwatering (Drought)

2. Underwatering: rosemary is a living plant after all, so don’t forget to give it enough drink
2. Underwatering: rosemary is a living plant after all, so don’t forget to give it enough drink

Now as I said Rosemary doesn’t need much water, don’t go to the other side and neglect watering the plant also!

An underwatered rosemary feels like it’s on the verge of becoming a plant version of a crunchy snack.

The stems and twigs are so dry that they snap easily because they’re seriously dehydrated.

To rescue your rosemary from this crispy state, water it until the surrounding 4-6 inches of soil looks all dark and moist.

This deep soak helps reach the deeper roots and rehydrate the soil.

If your soil mix has hydrophobic pals like peat moss or coco coir, it might need a bit more love.

Pour water over the soil until it happily flows out of the drainage hole for about 30 seconds.

Then, let the soil do its draining dance and take a break.

Check on your plant in the next 1-2 days—if it hasn’t perked up, it’s cool to give it another dose of hydration.

3. Poorly Drained Soil

3. Poor drainage: don’t forget to check the soil’s drainage ability. Rosemary would refer soil similar to succulent
3. Poor drainage: don’t forget to check the soil’s drainage ability. Rosemary would refer soil similar to succulent

Even if you’ve been following a watering routine that could get a professional nod, your rosemary might still be waving signs of water trouble.

The culprit? It could be poorly drained soil.

Rosemary thrives in well-draining, porous soil with an aerated structure that facilitates efficient root respiration, as it dislikes compacted soil.

Ideally, the soil should have medium to low fertility, and it should be rich in inorganic matter, resembling the sandy, gritty soils of its native hillside habitat. 

For potted rosemary, choose a well-draining mix like succulent soil with perlite, coarse sand, and pumice.

Alternatively, make your own blend using 3 parts potting soil, 3 parts coarse horticultural sand, and 2 parts perlite or pumice.

4. Pruning Into the Wood

4. Over pruning: It is perfectly fine to snip some rosemary branches for cooking, but over cutting into the wood would harm it
4. Over pruning: It is perfectly fine to snip some rosemary branches for cooking, but over cutting into the wood would harm it

Once you’ve got your rosemary plant thriving, the excitement of having fresh herbs on demand for your cooking kicks in—I feel the same way.

However, there’s a delicate balance because you don’t want to go overboard with the cutting and risk causing serious harm, especially by cutting into the wood.

Picture the woody branched center of your rosemary shrub like the trunk of a tree.

If you chop away too much of this wood, your rosemary might not make it.

When it comes to pruning, stick to hand pruners that smoothly handle small green twigs.

If you find yourself reaching for big loppers or a hack saw, you’re likely delving into the wood, and that’s a sign to hit the brakes immediately!

5. Pest Pressure

5. Pests: even as it is resistant to pests, rosemary is not entirely immune to “desperate” ones
5. Pests: even as it is resistant to pests, rosemary is not entirely immune to “desperate” ones

Thanks to its robust aroma, rosemary isn’t the top target for many pests.

However, this doesn’t mean the plant is entirely immune to sap-sucking insects.

You might encounter various pests such as spider mites, mealybugs, scales, aphids, or spittlebugs.

Combat them by spraying a forceful stream of water or pruning away infested branches.

Planting rosemary alongside other plants that attract beneficial predatory insects, like white alyssum, lavender, or sage, can also be a natural defense.

Regularly inspect the undersides of leaves, and promptly address any infestations to prevent damage.

For rosemary, you may still find pests like spider mites, mealybugs, scales, aphids, or spittlebugs
For rosemary, you may still find pests like spider mites, mealybugs, scales, aphids, or spittlebugs

6. Frost Damage

Rosemary is a warm-weather herb that can’t endure frost.

Exposing your plant to temperatures below 32°F might result in it shriveling and turning brown in the days that follow.

To ensure its well-being, bring potted rosemary plants indoors during the winter.

For those in zones 7 or colder, growing rosemary in containers may be necessary.

Gardeners in zones 7 and 8 planting rosemary outdoors might consider using a row cover or frost blankets to shield it from the cold during occasional snaps.

6. Frost damage: rosemary won’t be able to withstand persistent exposure to temperature below 32°F
6. Frost damage: rosemary won’t be able to withstand persistent exposure to temperature below 32°F

7. Excessive Heat

Rosemary thrives in warm temperatures, but if the mercury consistently climbs above 100°F, it can stress the plant if not adequately hydrated or ventilated.

Ideally, rosemary does best in temperatures ranging between 55 and 80°F.

During heatwaves, make sure to provide sufficient water for your rosemary to endure high temperatures.

If needed, consider offering some shade during extreme heat to support the plant’s well-being.

7. Excessive heat: this herb thrives in hardiness zones 7 to 10 and only likes temperatures between 55°F and 80°F
7. Excessive heat: this herb thrives in hardiness zones 7 to 10 and only likes temperatures between 55°F and 80°F

8. Not Enough Sunlight

For optimal growth, this aromatic herb needs 6-8 hours of direct sunlight daily.

Insufficient sunlight, leading to a lack of fragrance, is the most noticeable symptom of inadequate light for rosemary.

When cultivating rosemary indoors, position the plant near a south-facing window to ensure it gets enough sunlight.

If natural light is limited, consider using artificial grow lights to provide the necessary illumination.

8. Lack of sunlight: the plant needs at least 6 to 8 hours of direct sunlight to stay happy and strong
8. Lack of sunlight: the plant needs at least 6 to 8 hours of direct sunlight to stay happy and strong

9. Acidic Soil pH

Rosemary grows best in well-drained soil with a pH between 6.5 – 7.0, resembling the slightly alkaline conditions of its native environment on limestone rock.

A low soil pH can lead to yellowing and dieback, so regular testing and potential amendment with lime help create an optimal growing environment for rosemary.

9. Wrong soil pH: Rosemary likes slightly acidic soil with pH level ranging between 6.5 – 7.0
9. Wrong soil pH: Rosemary likes slightly acidic soil with pH level ranging between 6.5 – 7.0

10. High Humidity

Mediterranean plants, such as rosemary, thrive in dry, warm air, much like their native surroundings on windy coastal hillsides with constant breezes.

For those cultivating rosemary in humid climates, ensuring proper air circulation is crucial.

Improve air movement around the plant’s leaves by maintaining adequate spacing, avoiding overcrowding, and regularly pruning the plant to uphold an open structure conducive to free airflow.

Of course, you can totally invest in a dehumidifier if you feel like you need them.

I mean, if you don’t mind the cost of running the device 24/7 for the plant.

10. Wrong Humidity: in general, the plant would enjoy humidity level between 45% and 55%
10. Wrong Humidity: in general, the plant would enjoy humidity level between 45% and 55%

11. Powdery Mildew

Powdery mildew is a common and bothersome fungus that can affect most plants, potentially consuming their leaves before we have a chance to enjoy (eat) them!

If your rosemary appears as though it’s been dusted with white flour or exhibits a gray, moldy growth, it’s likely powdery mildew.

This fungus tends to spread in areas with high humidity and poor air circulation.

Combat powdery mildew with organic fungicides or neem oil applications.

Alternatively, you can remove infected parts, sanitize the environment thoroughly, and ensure the plant receives ample direct sunlight and airflow to prevent further issues.

11. Powdery mildew: you can easily treat it with better air circulation and neem oil treatment
11. Powdery mildew: you can easily treat it with better air circulation and neem oil treatment

12. Lack of Pruning

Yep, overdoing it with the pruning or just letting those leaves be, both have their issues!

While rosemary can tough it out without regular pruning, giving it a trim once or twice a year keeps it from getting all woody and encourages some fresh growth.

And here’s the deal – if your rosemary bush doesn’t toughen up for winter, it becomes a sitting duck for cold damage that could end up doing it in.

12. Lack of pruning: a haircut at least once a year improves air circulations and prevent it from turning woody
12. Lack of pruning: a haircut at least once a year improves air circulations and prevent it from turning woody

13. Too Much Nitrogen

Unlike garden vegetables, rosemary typically does well without the need for fertilizer or high-nitrogen compost.

Over-fertilizing can create a nutrient imbalance, leading to excessive growth and making the plant more vulnerable to problems.

Rosemary prefers lean soil and generally doesn’t need frequent fertilization.

Opt for a balanced blend, aiming for equal parts nitrogen, phosphorus, and potassium, indicated by NPK numbers like 10-10-10.

13. Too much nitrogen: Rosemary may suffer if you overfeed it with nitrogen. Aim for a balanced NPK 10-10-10
13. Too much nitrogen: Rosemary may suffer if you overfeed it with nitrogen. Aim for a balanced NPK 10-10-10

14. Overcrowded Plants

Rosemary shrubs have the potential to grow quite large.

When multiple plants are crowded together, they become more prone to issues like root rot, powdery mildew, and mold growth.

Additionally, they end up competing for resources.

If you find your rosemary plants growing too close, it’s a good idea to thin them out.

This not only enhances air circulation but also reduces resource competition, helping to prevent problems such as root rot and powdery mildew.

14. Rosemary will have issues competing for resources and space. Spread them out if you can
14. Bushes get overcrowded: Rosemary will have issues competing for resources and space. Spread them out if you can.

Sum up

With a solid grasp of rosemary’s requirements, growing this herb can be a breeze, and you won’t have to fret about yellowing or wilting leaves.

Just ensure you deliver the correct amount of water, sunlight, and well-draining conditions, and don’t forget to trim the plant as necessary.

To ensure the health and vitality of your rosemary plants, focus on the following key tips:

  1. Well-Draining Soil:
    • Plant rosemary in well-draining soil, especially if in containers. Avoid waterlogged conditions to prevent root rot.
  2. Watering Practices:
    • Maintain a balance in watering. Rosemary prefers to dry out between waterings, so check soil moisture regularly and water only when the upper inches feel dry.
  3. Sunlight Exposure:
    • Provide 6-8 hours of direct sunlight daily. Ensure adequate light for indoor plants, and consider using artificial grow lights if needed.
  4. Air Circulation:
    • Promote good air circulation around the plant. Avoid overcrowding, especially in humid climates, to minimize the risk of powdery mildew.
  5. Pruning:
    • Prune rosemary regularly to prevent it from becoming woody. Avoid cutting into the wood, as this can harm the plant.
  6. Protection from Frost:
    • Shield outdoor rosemary plants from frost using frost blankets, especially in colder zones.
  7. Pest Management:
    • Keep an eye out for spider mites and aphids. Treat infestations promptly to protect the plant.
  8. Soil pH and Fertilization:
    • Maintain slightly alkaline soil and avoid over-fertilizing with high-nitrogen compounds. Test and adjust soil pH as needed.

Now with these practical tips, I believe we can make our rosemary thrive! Happy gardening!