Sage leaves often become yellow as a result of stress brought on by moist soil. Sage can withstand droughts and prefers for the soil to dry out in between waterings. Additionally, excessive nitrogen from fertilizer or a nitrogen deficit from the roots being bound in a pot will cause sage leaves to become yellow.
When watered once every two weeks in sandy, well-draining soils, sage thrives best. As far as flavor and aroma go, sage leaves grow best on low- to medium-nutrient soils rather than high-nitrogen soils.
Continue reading to find out the cause of your sage’s yellowing leaves and how, by making a few straightforward changes to the growth environment, you may resolve the issue.
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Under Watering or Over Watering Causes Yellow Leaves
Sage is a Mediterranean herb that does well in full sun, well-draining soil, and can withstand drought.
Sage leaves will turn yellow as a symptom of stress if the soil is always damp because the roots prefer a period of relative dryness between waterings rather than constant moisture.
In moist soils, sage is more susceptible to wilting and fungal disease. (Read my post on the causes of sage plant wilting and remedies.)
Sage’s leaves turn yellow for four primary causes, including chronic wetness surrounding the roots:
- watering too much
- sluggish drained soils (such as clay)
- large rains
- pots without a base drainage hole
Watering…
Sage should generally be watered every two weeks if the weather has been a mix of cloudy days, some sun, and possibly some rain.
Every week during the summer, water sage. Skip watering until the soil is substantially dry if there has been rain and the ground feels moist.
Sage can become overwatered and develop yellow leaves if you water it more frequently than once per week.
The remedy for excessive watering
Reduce watering so that the soil can have a chance to dry out between rain or extra watering. Sage is a native of dry Mediterranean climates, therefore gardeners should be careful not to overwater it.
Sage should receive a generous soak every time you water it to help the roots take root.
Reduce watering and let the soil dry; after two weeks, the sage leaves should start to recover. The flavor of sage plants is improved by proper watering.
sluggish-draining soil
Soil drainage is a further concern that needs to be addressed.
Sage is adapted to grow in soils that do not hold much moisture because it grows in sandy or stony soils on hilly slopes in Southern Europe.
In contrast to the sage’s optimum soil conditions, slow-draining soils like clay or rich compost in bog parts of the garden store too much moisture, which can lead to stress and yellowing of the leaves.
The remedy for soils with sluggish drainage
Due to the pots’ good drainage and ease of soil profile adjustment, sage grows quite well in them. Planting in pots is an excellent choice to maintain the plant healthy and the foliage green if your garden has slow-draining soil.
If you’re planted near garden borders, you can also add horticultural sand or grit to the potting mix or planting area.
The sand or grit will aid in simulating the sandy soil conditions to which sage is accustomed and will also help to enhance drainage, which keeps the roots dry and prevents the leaves from turning yellow.
For the best drainage and the ability of the roots to dry out after watering, mix at least 20% of multipurpose compost with sand or grit before planting your sage plant in the ground or in a container.
Heavy Rain…
While sage is a hardy plant that can withstand rainy conditions provided it is in full sun and the soil has been prepared prior to planting to improve drainage, high rainfall is also troublesome for sage and Mediterranean herbs in general.
The remedy for heavy rains
I would advise adding at least 30% sand or grit (by volume) to the soil in locations that see frequent rain, with the remaining compost. Sage prefers the sandy soil of the hillsides where it grows naturally, so do not be afraid to add a lot of sand or grit. Too much sand is always preferable to not enough.
Sage can thrive in environments with high rainfall if the soil drainage is improved, and the leaves can turn a healthy green rather than yellow.
Sage is sometimes planted in attractive pots without drainage holes in the base, or the surplus water is collected in the pot using a drip tray.
Sage will begin to wilt and become yellow as a result of stress from too much water if water cannot drain away, causing the soil to quickly get soggy.
To avoid the sage leaves from turning yellow, choose a pot with drainage holes in the base that is 12 to 16 inches across.
Sage plants that are wilting and developing brown leaves are most likely suffering from root rot. To learn why sage plants become brown and how to fix the issue, read my post.
The underwatering
Due to its Mediterranean origins, sage is drought resistant, therefore underwatering is not usually a concern. However, sage leaves can turn yellow if the pot is indoors and has been neglected for weeks.
During the Spring, Summer, and Fall, water indoor sage plants once every two weeks. If the leaves start to turn yellow, the sage should recover.
If the sage plant’s pot is too small and made of plastic or metal, that could also be an issue. The soil dries out too soon for the roots to absorb in small pots because they heat up more quickly in the sun.
More soil is present in a larger container, allowing the roots to develop and draw in the water they need. Choose a clay, terracotta, or ceramic pot instead of a thin plastic or metal one since they do not heat up as rapidly, which can cause the soil to dry up too quickly.
Too Much Fertilizer, Nutrient deficient or Pot Bound Roots
As a result, many sage types may grow in low- to medium-nutrient, well-draining soils that contain a sizable amount of sand or grit.
In contrast to the sage’s optimal soil conditions, planting sage in soil with a high nitrogen concentration (such as soil supplemented with manure) or the use of excessive fertilizer can result in stress, including:
- changing yellow leaves
- an appearance of drooping stems and leaves
- less flavor and less odor coming from the leaves
Under certain circumstances, nitrogen fertilizer can be effective for promoting sage plant development.
Sage, on the other hand, is not a picky plant and frequently does not need any additional fertilizer. In fact, if you are growing sage for culinary use, using too much fertilizer will harm the flavor of the herbs and make them seem yellow.
Sage plants should recover if fertilizer has been administered to them and you notice excessive growth and yellowing leaves. In this case, hold off on fertilizer application for a time.
Sage plants require little upkeep, and the more closely you can mimic their natural growing environment, the better they should grow and the more flavorful the leaves should be.
Mix at least 20% horticultural sand or grit with multipurpose compost in the planting area or the pot to mimic the low to medium fertility soil conditions in which sage thrives.
This guarantees that the sage plant has the proper ratio of nutrients and sufficient drainage, resulting in a healthy plant with greener, less yellowish, leaves.
Not Enough Nitrogen
Sage does need some nitrogen, phosphorus, and potassium (as well as some trace elements) to grow properly, even though it prefers low to medium nutrition soil.
It may be perplexing because too much nitrogen can also cause leaves to turn yellow, while a nitrogen deficiency will induce yellowing of the leaves.
However, sage rarely experiences a nitrogen shortage, and the causes of sage becoming yellow are typically excessive watering or fertilizer use rather than a lack of nutrients, although there are some circumstances in which this can be a problem.
Lack of nutrition can lead sage leaves to turn yellow, and this is more common when:
- Sage that has been growing in a pot for a long time without being replanted
- The plant is root-bound in a pot that is too tiny.
Due to the sage plant’s roots’ constrained access to soil and nutrients in both of these situations, it may run out of nutrients in the pot.
Sage should be planted in a container that is 12 to 16 inches across in order to maintain its health. The sage roots won’t become pot-bound as a result, and there will be more dirt and nutrients available as well as insulation for the roots, which are sensitive to the cold.
If the sage plant seems yellow, repot it in a larger pot with fresh compost to give the roots more nourishment.
In this situation, a spring application of a half-strength general all-purpose fertilizer can be beneficial for promoting new growth and ensuring the sage has access to a variety of nutrients in case it has been experiencing a nutritional deficiency, such as a lack of nitrogen or perhaps a trace mineral.
Sage should only receive fertilizer once in the spring and only at half intensity because too much fertilizer will do more harm than good by stimulating growth that is more vulnerable to frost damage.
This will promote growth and address the nitrogen shortage that within a few weeks will cause the leaves to change from yellow to green.
Key Takeaways:
- The main cause of sage becoming yellow is overwatering. Sage is a Mediterranean herb that prefers dry soil over moist soil, which results in yellowing of the leaves.
- To mimic the arid conditions of their original Mediterranean habitat, reduce watering to once every two weeks, enrich the soil with sand or grit, and put sage in pots.
- For sage, too much fertilizer can be too harsh, and too much nitrogen will make the leaves yellow. Sage with roots connected to a pot may have a nutrient shortage and become yellow. If the sage is in a small pot with pot-bound roots, repot it in the spring and apply a half-strength all-purpose fertilizer.