How To Revive A Yellowing Russian Sage Plant

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How To Revive A Yellowing Russian Sage Plant

If you have a Russian sage plant and its leaves are turning yellow, you may be dealing with a nutrient deficiency, specifically a lack of nitrogen. Nitrogen is important for the production of chlorophyll, which is responsible for the green color of plants. When there is a shortage of nitrogen, the chlorophyll content decreases, causing the leaves to turn pale yellow. Older leaves are usually affected first, and the yellowing is uniform and not vibrant.

To address this issue, fertilize the Russian Sage with a balanced, slow-release fertilizer that contains nitrogen.

Another reason for yellowing leaves is water-related problems, such as overwatering or poor soil drainage. Overly wet soil can cause root rot and impair the plant’s ability to absorb nutrients and water, turning the leaves yellow. The yellowing leaves may also appear wilted or droopy. Excessive moisture can also lead to the development of mold or mildew on leaves.

To fix this problem, plant the Russian Sage in well-draining soil and allow the top few inches of soil to dry before watering again. Consider adding organic matter to the soil to improve drainage if necessary.

How to fertilize Russian sage properly

Russian sage and yarrow flowers

Kathryn Roach/Shutterstock

When choosing a fertilizer for Russian sage, you must select a balanced, slow-release fertilizer. Specifically, you want to look for a fertilizer with a nitrogen-phosphorus-potassium ratio of around 5-10-5. Moreover, only fertilize once a year or less, as over-fertilizing can create an unhealthy plant.

To apply the fertilizer, start by carefully reading the instructions on the packaging. Typically, you will sprinkle the fertilizer evenly around the base of the Russian sage plant, avoiding direct contact with the leaves. Use a garden fork to lightly work the fertilizer into the top few inches of soil. Be careful not to damage the plant’s roots during this process.

In terms of timing, it is generally recommended to fertilize Russian sage once a year, in early spring or late winter, before new growth begins. This will provide the plant with the necessary nutrients to support healthy growth throughout the growing season. However, if your Russian sage is still showing signs of nutrient deficiency, such as yellowing leaves, you may consider applying a second round of fertilizer in mid-summer. When determining the amount of fertilizer to apply, follow the instructions on the packaging. The recommended amount will depend on the size and age of your Russian sage plant. Remember to water the plant thoroughly after applying the fertilizer to help it absorb the nutrients effectively.

How to improve drainage through aeration

Gardener holds a soil aerator

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Another key cause of yellowing leaves in Russian sage plants is poor drainage. Poor drainage can be caused by compaction, which is when the soil becomes compressed, making it difficult for water to escape through pores in the soil. Compacted soil can restrict root growth and hinder the plant’s ability to absorb nutrients and water.

If you suspect that your Russian sage plant is suffering from compacted soil, then you’ll need to gently aerate it to improve drainage. One way to do this is to carefully dig around the plant’s base with a hand trowel or garden fork, avoiding damage to the roots. Gently loosen the soil and turn it over to improve aeration and water penetration. Next, add a layer of organic mulch, such as compost or well-rotted manure to improve soil structure and retain moisture. Avoid piling mulch against the plant’s stem.

Another option to improve drainage around a Russian sage plant is using spike aeration. Using a spike aerator tool, insert spikes or tines into the ground at intervals around the plant, ensuring they penetrate at least 2 to 3 inches deep. This process creates small holes in the soil, allowing for better water and air infiltration. After aeration, apply a layer of well-draining soil or compost and mulch around the plant to further enhance drainage and promote a healthier Russian sage.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.