Yellowing leaves on Jasmine
My daughter has a jasmine, been in the ground for a couple of years. No blooms, leaves turn yellow with brown spots and fall off easily. Planted next to a variegated jasmine, which is doing fine as far as the leaf color. She has asked several different sources what the problem might be. Potassium, nitrogen, compost, prune, etc. Different solutions, nothing is working. Any suggestions? She's a new home owner and just really getting into the flowerbed stuff, so any help will be great.
Linn County Oregon
Hi and thanks for contacting Ask an Expert.
Jasmine can have a number of issues from pests to disease, but this may be a problem called chlorosis. The leaves are yellow but the veins in the leaves stay green. Check out the leaves and see if the leaves look like this. If so, the next step is to check the pH (acidity or alkalinity) of the soil. Jasmine can grow in both acidic and alkaline soils but does better in acidic soils. You can get a cheap test for pH at any nursery or anywhere they sell plants, pots, etc. The Linn County master gardeners will check the pH of your soil free of charge. If you buy a test kit, follow the directions, take soil samples and check out the pH. If it is higher than 7 which is neutral, add some sulfur (powdered) to the soil along with sawdust. Mix into the soil and water in.
The problem is the plant cannot take up enough iron and because of that it cannot perform its function (photosynthesis) in order to make sugars. Iron helps the plant develop chlorophyll which aides in photosynthesis. Iron is usually prevalent in the soil and the plants can take it in more efficiently when the soil is around pH 5.0 - 6.5.
You can add chelated iron to the soil and work it in too.
Another problem could be compacted roots, or broken, diseased or rotten roots. Has there been any rototilling around this plant. They like well-drained soil with a lot of compost or organic matter.
Most of the soil in our area is full of clay, adding organic matter will help break it up and it will drain better.
Over watering can also be a cause. With all the rain we are having now, you won't need to water for a while. Let the soil dry out before watering after the rains stop.
Also too much phosphorus in the soil can be an issue. That same pH test I spoke of also has tubes to test nitrogen, phosphorus and potassium. Or, you can contact a soil lab and take a soil sample in for testing. The master gardeners do not test for those elements.
Use an all-natural fertilizer not a synthetic one. Look for OMRI on the package. Also there are three numbers on fertilizer bags. The first number is for nitrogen, the second for phosphorus and the third for potassium, all macro nutrients. Find one that does not have a high middle number (phosphorus). It will look like this: 5-5-5 or 5-1-1, any combination of numbers. This tells you the percentage of the nutrient in the bag - so 5-1-1 is five percent nitrogen and 1 percent each phosphorus and potassium.
If this is not the issue, write back and we can explore other possible causes. Please send a photo of the leaves if you do re-contact us.