Rose leaves turning yellow – Gardener Report

Rose leaves turn yellow as a result of too much fertilizer, nutrient deficient soil, drought stress, saturated soil, not enough light or because of fungal disease. Rose leaves turn yellow and drop off in Winter as they enter a state of dormancy. In most cases roses with yellow leaves indicate an environmental stress often because of water or soil nutrients and these problems can be easily resolved. Keep reading to learn the cause of your yellow rose leaves and how to solve the problem... Too Much Fertilizer Turns Rose Leaves Yellow Rose leaves can turn yellow as a reaction to fertilizer applied too frequently or in too high a concentration. Fertilizer contains salts which build up after repeated use of additional fertilizers when feeding your roses. This salt accumulates in the soil around the roots and draws moisture from the plants and prevents any uptake of moisture causing a burn and yellow appearance of the leaves. Excess fertilizer can also cause drooping growth that is more susceptible to disease and prevent the rose from flowering. (If your roses are not blooming, read my article to learn why and how to promote more flowers). This highlights the importance of moderation when fertilizing your roses. However you should also consider whether other sources of fertilizer are perhaps affecting your rose such as run off from frequent lawn fertilizer applications as feed is often water soluble and can affect your garden boarders after heavy rainfall. How to solve it: The best way to avoid this problem is to use a specific formulated rose fertilizer. I personally prefer miracle-gro granulated rose feed as it contains the right balance of nutrients at the right level of concentration for roses and the granules release the nutrients over time which prevents the leaves turning yellow and the other problems associated with too much fertilizer. The best fertilizer for roses. Scale back the use of any fertilizer for the time being if you suspect it is the cause for your rose leaves are turning yellow. Cut back any severely affected foliage with a pair of pruners and water the rose well from the next few weeks and the rose should recover. (Read my article, why is my rose drooping?) Nutrient Deficiency Causes Yellow Leaves Rose leaves turning yellow are potentially a sign of stress due a lack of nutrients in the soil. Rose leaves most commonly turn yellow due to a lack of nitrogen in the soil. Roses are heavy feeders and require nitrogen to form chlorophyll for the leaves to be green and the plant to photosynthesise. Yellow rose leaves is a signs of stress due to a nitrogen deficit in the soil. However it should also be noted that rose leaves can turn yellow as a reaction to a lack of magnesium and iron in the soil. Rose leaves are more likely to turn yellow if the soil is sandy and nutrient poor as this is contrary to their preferred soil profile. Sandy soils do not retain moisture or water soluble nutrients (such as nitrogen) so annual applications of fertilizer are important. How to Solve it: To reverse yellow leaves due to a lack of nutrients, use a well balanced fertilizer made specifically for roses (there are many products available but I have had success with miracle-gro) and apply a 1 inch layer of mulch to the surface of the soil around the base of the rose. Use materials such as compost, leaf mould or well rotted manure for mulch as these three materials have an excellent capacity for holding moisture and add nutrients to the soil over time. Apply the mulch once in the Spring and again in before Winter (to help insulate the cold sensitive roots and continue to improve the soil). With consistent applications of fertilizer and mulch the rose should recover over the next few weeks. Please note that fertilizer should only be applied to the soil in Spring after the threat of frost has passed and do not apply any more after the 15th of August as fertilizer stimulates new tender growth which is more vulnerable to frost damage in the upcoming Winter. Rose leaves can also turn yellow due to an iron deficiency which is caused by alkaline soils... Soil pH- Iron deficiency Causes Yellow Rose Leaves Soil Gauge to measure the pH of soil. If the soil pH is too high then this can cause an iron deficiency which causes the veins of the leaf to remain green yet the rest of the leaf turns yellow. Alkaline soils can affect the availability of nutrients in the soil such as iron and magnesium which results in yellow leaves on your rose bush as a sign of stress. Roses prefer a mildly acidic soil and can grow in a pH range of pH 6-7 without problems associated with nutrient availability. If your garden soil is alkaline (above pH 7) then this is the most likely cause of your rose leaves turning yellow. How to Solve it: Determining the soil pH of your soil can be as easy as asking your gardening savvy neighbours what the soil pH is in the neighbourhood. Alternatively you can use a soil gauge that you can buy at garden centers or on amazon. Soil gauges are very easy to use, and accurately tell you the pH of your soil so that you can plant out your garden according to your soil conditions. Best of all they are available for a great price. How to solve it: If you test your soil and the pH is higher then 7 then I recommend transplanting your rose if possible to a pot or raised beds as your garden soil is not suitable for growing roses. If your transfer the rose to a pot then you have control over the soil profile and can customize the soil with a rose potting mix so that your roses thrive rather then trying to amend your soil with sulphur to make it more acidic. Transferring your rose to a pot or raised bed also means that it is no longer exposed to the alkaline soil and the rose can start to make a recovery and eventually the yellow leaves should revive to a healthy green colour. Drought Stress can Cause Rose Leaves to Turn Yellow Roses require soil to be consistently moist to a depth of around 8-12 inches. If the soil dries out for too long then the the rose's leaves turn yellow as a sign of drought stress. Yellow rose leaves due to drought stress can occour because: The soil is sandy or low in organic content and therefore does not retain enough moisture.The sunlight and heat is directly at the base of the rose which increases evaporation from the soil.Heat waves and lack of rainfall due to seasonal variation in weather.If roses are planted in pots or containers the pot has less capacity for soil and therefore less capacity for moisture. Pots can heat up quickly in the sun and dry out causing drought stress and yellow leaves. For most climates and conditions, watering your roses once a week with a generous soak is enough for your roses to thrive and to prevent drought. However the watering frequency should be adjusted to your climate and soil conditions so that the soil stays consistently moist (but not saturated) to prevent yellow leaves. How to Solve it: Once of the best ways to prevent drought stress and to revive your rose with yellow leaves is to use a mulch around the base of the rose. Apply a 1 inch layer of compost to the surface of the soil around the base of the rose to help conserve moisture and improve the soils moisture retaining capacity. Mulch also helps to shade the soil and keep the roots cool. A soaker hose can be useful for maintaining soil moisture in hot climates. With consistent watering at the use of mulch your rose leaves should recover from the yellow appearance over the next few weeks. Over watering or Saturated Soils Rose leaves can turn yellow as a result of their roots being deprived of oxygen due to saturated soils. Roses require soil that is consistently moist yet has a light, friable, aerated structure to allow for root respiration. If the soil is boggy and not well draining then this can prevent oxygen reaching the roots which causes the leaves to turn yellow. Three common reasons or the soil to being saturated around your roses are: Over watering.Roses planted in slow draining soil (such as clay) or in naturally boggy areas of the garden.Roses planted in pots and containers without drainage in the base. To avoid over watering and depriving your rose roots of oxygen it is important to water roses appropriately for your climate and soil conditions. The optimal balance of soil moisture for roses is for the soil to be consistently moist (but not damp) to a depth of 8-12 inches. This is achieved by planting roses in lots of organic matter (compost or leaf mould) applying mulch and watering with a generous soak around once per week during the Spring and Summer with additional watering during heatwaves. If you are watering your rose every day, this is too frequent and can result in the leaves turning yellow, scale back watering to around once per week and only water during Spring and Summer. If the soil is boggy and damp all the time because it is low lying or just drains slowly then it is likely that not only the leaves turn yellow but the rose will develop the disease root rot and die. Transplant roses into better draining soil or perhaps a raised bed. With raised beds it is far easier to make the soil profile suitable for roses compared with amending your boggy garden soil. However it is possible to amend clay soils with lots of organic matter to improve the structure and drainage characteristics so that it is appropriate for growing roses. Potted or container roses should always have drainage holes in the base of the pot to allow excess water to escape so that the soil does not become saturated. (Read my article, choosing the best post for roses). Rose Leaves Can Turn Yellow In Winter Most roses are deciduous and so drop their leaves and go into a dormant state before Winter. As part of the leaf shedding process the leaves may turn yellow prior to dropping off. So if the cold Winter season is correlated with your rose leaves turning yellow then be assured the rose is not dying but just preparing for Winter by to dropping it leaves before growing again in the Spring. Not Enough Light Rose leaves can turn yellow as a consequence of a lack of direct sunlight. Roses require at least 6 hours of sun to grow and flower at their best so if they are in full shade they do not bloom to the same extent and often the leaves turn yellow as a sign of stress. If your rose is in a shaded area then I would recommend either transplanting the rose or cutting back anything that may be casting shade on the rose such as a the limb of a tree that may have grown significantly and cast shade over a once sunny area of your garden or any surrounding shrubs and vegetation. Alternatively you can transplant the rose to a sunnier location in your garden. This should not only resolve the problem of the leaves turning yellow but also promotes flowering and improve the overall health of the rose. Sometimes the leaves lower down of the rose bush are turning yellow whilst the top leaves remain a healthy green colour. This is because the top leaves are in the sun and have optimal light exposure whereas the leaves that are near the bottom or on the shaded side of the plant can turn yellow because of the comparative lack of sun. Leaves that are in the shade tend to turn yellow and drop off as the rose redirects its resources to the healthy leaves that are in more sun. Pruning back the foliage that is turning yellow can reduce the stress on the plant so that it flowers in the Summer. Fungal disease Causing Roses Leaves to Turn Yellow Rose leaves yellowing because of the fungal disease black spot. Rose leaves can turn yellow as a consequence of fungal disease with black spot being the most common reason why rose leaves turn yellow around areas of black. The yellow and black leaves eventually drop off and it detrimentally affects the health and flowering of the rose. Black spot is unfortunately a common rose disease, however it can be treated and the rose can recover. How to treat black spot: Cut away any affected leaves with a sterile pair of pruners. Use a cloth soaked in alcohol disinfectant to wipe the blades after every cut to prevent potentially spreading the spores of the fungus to otherwise healthy growth.Burn the leaves or discard of them rather then put them in the compost as the fungus can lay dormant in a compost heap and affect other plants.Use a specialised rose fungicide spray to spray the leaves of your rose (available from garden centers and amazon). Black spot can be prevented with good care practices for roses such as: Water at the base of the rose rather then overhead to decrease humidity. Plant roses around 3 feet apart for good airflow.Water the rose consistently and apply mulch to maintain soil moisture.Use a fertilizer at the start of Spring so that the rose has all the nutrients it requires to stay healthy and disease resistant. A healthy rose is far more resistant to the fungal diseases that turn rose leaves yellow so best practices of care are essential for the health of your roses. (Read my article, why is my rose wilting?) Key Takeaways: Rose leaves turn yellow because of environmental factor such as a nutrient deficit soil or because of too much or too little moisture at the roots. Too much shade and fungal disease can cause leaves to turn yellow and drop off.Rose leaves often turn yellow in Winter as they are deciduous and naturally turn yellow and drop before a state of Winter dormancy.Rose leaves in too much shade can turn yellow and drop off and require transplanting to a sunnier area of the garden.A high soil pH can cause chlorosis where certain nutrient such as iron and magnesium are unavailable for uptake at the roses roots.Applying fertilizer too frequently or in too high concentration can lead to build up of salts which cause your rose leaves to lack moisture, burn and turn yellow