Why Does Your Sage Keep Dying? 5 Causes and Fixes

It can be frustrating to grow sage in your garden because if it keeps dying for no apparent reason. No matter what you do or try, it just feels like you have no luck with this plant. What is causing these plants to die, and is there something you can do beforehand to enjoy a successful harvest?

Sage can die from plant diseases like crown gall, rust, and verticillium wilt. Common pests like spider mites can damage sage plants over time and, if left unchecked, result in their death. Moreover, root rot can take hold of sage plants due to overwatering, causing them to die over time. 

This guide provides extensive information about some of the pests and diseases that sage plants are most susceptible to. It also covers solutions to overcome these problems so your sage plants can thrive. 

1. There’s a Severe Crown Gall Infection

This is a bacterial disease caused by Agrobacterium tumefaciens. When it affects your plant, you’ll find gall or ball-like structures on the sage plant’s stems and roots. 

Initially, the galls on the plant are soft and sponge-like when you touch them. As the disease gets hold of the herb, they become hard. The color of the galls changes from a light shade to a dark one.

The problem with crown gall is what happens to sage plants if you don’t take immediate action. First, it restricts the flow of nutrients and water throughout the plant, reducing the growth of the flora. If it manages to cover a portion of the stem completely, a process known as stem girdling, the plant won’t survive. Young plants will also die due to this disease.

There are also other problems that crown gall introduces to sage. For instance, it makes the herb vulnerable to other bacterial diseases. Bacteria can enter the plant through the galls and cause infections. The condition also makes sage susceptible to drought stress due to reduced water movement throughout the flora.

How Does Sage Get Crown Gall?

Before explaining how to combat this plant disease, it’s essential to know how it affected the sage in your garden in the first place. 

Agrobacterium tumefaciens, the bacteria causing this disease, has to be present in the soil. There are two ways this can happen—you may have planted sage or other flora with this disease, or it was already lying dormant in the soil.

This bacteria can remain dormant for months, even years. As a result, it can spread to other species in your garden.

Crown gall must enter inside the sage to infect it. One way it gains access to the flora is through damaged roots. This can happen while planting it in the soil. Insects in the soil can damage the roots and create wounds, allowing this bacteria to enter the insides of the sage plant. 

It’s also possible for the bacteria to affect the sage in your garden if the roots have been broken or damaged while you were transplanting it. 

How To Fix 

Below are a few ways to prevent crown gall from taking hold of your garden.

  • Examine each plant carefully before planting it. If you notice any galls on the stem or roots, discard them immediately.
  • Dip plant roots in an agrobacterium radiobacter K-84 solution to protect them against bacteria that cause crown gall. It’s a biological control bacteria that helps the plant produce an antibiotic to combat this harmful microorganism. 
  • Sterilize all garden equipment after you use them, especially if the plant already has crown gall. This prevents the bacteria from spreading to other plants when you use the tools again.
  • Discard all infected plant material to stop the disease from affecting other plants. You must burn the disease-ridden plant material instead of adding it to the compost pile. 

2. Sage Is Affected by Rust Disease

Rust appears due to a fungus from the Puccinia family. When it affects your plant, it starts forming pustules. These resemble pimples, and you’ll find them on the underside of the leaves. Generally, they are brown, bright orange, or yellow. 

Although it doesn’t pose much risk initially, rust can cause your sage plants to die when the infection becomes severe. Once rust affects the flora, the new shoots that appear will be distorted and pale. They also break easily.

The foliage will die and fall off as the infection spreads throughout the plant. 

This happens because the fungi control where the plant’s resources go. Instead of going to the flora, they end up in the fungi. Over time, this will make your plants look less vibrant.

How Does Sage Get Rust?

Rust requires a host plant to survive. If you get infected sage plants from the nursery, the infection will be active in your garden.

Once the fungi produce their spores, they will wait until winter ends to spread them. The fungus survives winter by creating a thick wall to protect itself from the cold. Once the temperature increases, it will become active and spread to other parts of the plant. 

If infected sage plants are in your garden, wind can direct the spores toward non-contaminated herbs. However, the plant surface has to be wet for the spores to produce new fungi.

How To Fix 

Follow these methods to prevent rust from damaging your sage plants.

  • Examine all new plants before you introduce them to your garden. If you notice this disease on the leaves, discard the flora immediately. 
  • Remove infected leaves from the plant and discard them. Avoid pulling out more than ⅓ of the leaves as this can affect growth.
  • Ensure there is adequate space between each plant in your garden. Lack of space increases humidity levels, increasing the chances of this disease affecting your flora.
  • Water plants early in the day, especially if you use sprinklers or overhead watering techniques. This provides enough time for the water to evaporate from the leaves, making it harder for the spores to grow. 

3. Verticillium Wilt Has Overtaken Your Sage

Verticillium dahliae is a fungus that affects sage plants. The leaves will turn yellow over time when it infects the herbs in your garden. Slowly, the plant tissue starts to die, especially at the bottom. You will notice this as the stem becomes brown or black.

These fungi target the plant tissues that are responsible for transporting water. By stopping water from flowing towards the leaves, the foliage will wilt. If you allow the disease to continue unchecked, it will result in the death of the sage plant. 

How Does Sage Get Wilt?

The fungi causing wilt can be present in your soil. As it can survive up to 10 years without a host, it will affect multiple plants, even if you sow them after a long time.

Another way wilt spreads is through infected material. For instance, buying plants with this disease will allow these fungi to enter your garden.

Plants that have wilt can also spread pathogens through their leaves. 

These fungi thrive in heavy clay soils that lack proper drainage. Additionally, you may find these fungi in areas where the soil temperature is 70°F (21°C)

If the roots get damaged while planting or transplanting, fungi can enter the plant through them and spread.

How To Fix

Use the following techniques to ensure wilt won’t be a problem in your garden.

  • Only buy plants from trustworthy nurseries. As it can be challenging to spot this disease during the early stages, you may only notice it when it is too late.
  • Eliminate infected plants as soon as possible. This helps prevent the disease from spreading throughout your garden.
  • Clean all gardening equipment immediately after use, especially if handling infected plants. For instance, if your boots are full of soil and you walk to other parts of the garden, you may spread the fungi accidentally. 

Avoid using fungicides for treating wilt, as it isn’t economically feasible. While products like Benlate 50 WP can help when you dip the sage before planting it, it won’t work in the long run. This is because the new root growth won’t benefit from the effects of this fungicide.

4. There’s a Spider Mite Infestation

Spider mites are pests that attack sage and other plants in your garden. Initially, you may only notice a few of them on your flora. However, their lifecycle from egg to adult reduces to 7 days when the temperature goes above 85°F (29.4°C). Moreover, a female spider mite can lay up to 100 eggs. If you don’t control their population, you’ll be dealing with an infestation. 

Their primary food source is chlorophyll, which is present in the leaves. By draining it from the foliage, the leaves get damaged. Over time, they become yellow and fall off the plant. They also target new growth in your plant. As a result, your sage’s growth and yield will be reduced. 

Once they establish a colony on your sage plants, you’ll notice tiny webs all over the flora. If you see this, it’s a clear indicator of an infestation. 

You can also look for these insects. However, you’ll need a magnifying glass with 10x – 20x magnification to spot them because of their minute size. Make sure you check the underside of the leaves.

They target water-stressed flora as these plants have additional amino acids, attracting spider mites. 

How To Fix

Luckily, there are several ways to deal with spider mites

Implement Natural Control Techniques

If you want to avoid using insecticides or other chemicals, here are some handy tips for dealing with these pests.

  • Make sure you irrigate your garden regularly. Dry soil will water-stress the plant, making it susceptible to spider mites.
  • Use a water spray to knock the spider mites off the plant and remove the webbing. This will make it harder for the pests to spread. Overhead watering will also work, but make sure you only do it during the early morning.
  • Cover the soil with mulch to prevent excess moisture evaporation. This technique is helpful if your area faces high temperatures or arid weather. 
  • Avoid over-fertilizing the soil. New growth is food for the spider mites, and the plants also produce excess amino acids, which help these pests thrive. 
Use Biological Control Agents

Biological control agents are predators that target specific species of pests. By feeding on these insects, they ensure the population of these pests doesn’t get out of control. Here are some biological control agents you can use in your garden.

Phytoseiulus Persimilis

They are predatory mites that focus on attacking spider mites in your garden. These organisms are red, slightly bigger than spider mites, and have a pear-like shape. They also have long legs. 

Looking for eggs is the best way to know these predatory mites are thriving in your garden. Their eggs are larger than spider mites’ eggs. Additionally, they tend to be more oval than round.

Feltiella Acarisuga

Another insect you can rely on to protect your garden from spider mites is Feltiella acarisuga. While they eat hairy leaves, they also feed on spider mites. You can buy them as pupae and spread them throughout your garden. 

Once the adults hatch and establish themselves, they’ll start laying eggs. They will be located near spider mite infestations to ensure the larvae feed on the pests. 

Moreover, when they become adults, they can fly. This allows them to reach any part of the plant that is suffering from an infestation.

Stethorus Punctillum

A predatory species of lady beetles, these insects love eating spider mites. They will target pests in all stages—from egg to adult. Like the Feltiella acarisuga, they can also fly, making it easy for them to search and find spider mites in your garden. They are small, have oval-shaped bodies, and are black in color. 

Use Insecticidal Soap

Another way to avoid chemicals in your garden is to use insecticidal soap. The active ingredient in these products is potassium salt, derived from fatty acids. 

The best part about insecticidal soaps is that you can target a variety of pests like aphids, spider mites, mealybugs, and whiteflies, commonly found on sage plants. However, they can also harm predatory mites or lady beetles. You should avoid using these products if you’re taking advantage of these beneficial predators.

How To Use Insecticidal Soaps?

These products only work when they come in direct contact with pests. In other words, if the solution dries up, it won’t be effective. This allows you to introduce biological control agents after using this product.

Make sure you test this type of product before coating your sage plant with it. Apply it on a small portion of the leaf and wait for 24 hours. If you don’t see any signs of damage, you can use it safely.

Follow all the instructions written on the label. Before you mix it with water, you should know the hardness level of the water in your household. Hard water, which contains calcium, iron, and magnesium, will precipitate the fatty acids. This reduces their effectiveness. 

Ensure you cover the plant with insecticidal soap, especially the underside of the leaves, as this is where the spider mites reside. 

You should also check the temperature before applying the soap to the sage plant. If it’s above 90°F (32.2°C), the solution can damage the flora. Additionally, don’t increase the concentration, as this may harm the herb. Lastly, avoid using these products if the plant is under water stress. 

5. Your Sage Is Suffering From Root Rot

Root rot can occur if you overwater your sage plants. Although sage is resistant to phymatotrichum root rot, other microorganisms can affect the plant. The easiest way to identify root rot is to look at your sage.

If you notice it’s wilted despite the soil being wet or watered recently, this disease is affecting your herb. You may also see the leaves change color to yellow. This indicates that your flora is not receiving enough nutrients from the soil. 

How To Fix

Here are a few handy tips to help you deal with root rot. 

  • Ensure the soil has adequate drainage to prevent the build-up of water beneath the surface. This will prevent root rot from affecting the sage. 
  • Only lightly water the plant to prevent overwatering. Always wait for the soil to become dry before watering it again.
  • Remove any infected plants as soon as you notice them. Make sure you don’t add these contaminated plants to the compost pile. 
  • Rotate what you grow in your garden to prevent the build-up of organisms that cause root rot. This allows the soil to balance itself out, reducing the chances of the disease spreading in the future. 

Sage plants can develop other issues that may need immediate action. If you notice white spots on your sage, check out my article on what causes this issue and how you can resolve it: Why Does Your Sage Have White Spots? 4 Causes and Fixes


Crown gall, root rot, rust, and verticillium wilt are all diseases that commonly affect sage plants. If these conditions are allowed to spread and turn into infections, they’ll result in the death of your herbs. Luckily, as long as you follow the solutions highlighted in this guide, you’ll be able to manage them effectively.

Keep an eye out for pests like spider mites, as they consume the plant’s chlorophyll. They’re able to spread quickly in warmer temperatures, causing an infestation and, ultimately, the death of your sage. Natural control techniques and insecticidal soaps can help keep them in check.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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