I read many of your posts and thought you might be able to help. I recently purchased four 3-foot-tall juniper trees and planted them in containers on our patio about two weeks ago. Now, some of the tips of the needles are turning yellow. I watered them well after planting and we’ve gotten a reasonable amount of rain since then. The containers do allow them some room and have drainage. They’re also getting full sun though it hasn’t been particularly warm yet in Chicago. Could they be over-watered? I know they won’t be happy in containers forever and will get them into the ground in a few years.
The Gardener’s Answer
Hi, Leslie: Without seeing your plants I can only speculate, but some evergreens are more susceptible to environmental conditions and winter damage than others. Both of these factors could be causing your plants to have yellowing tips. There are many species of juniper and some are more disease-resistant than others, but spider mites are a very common problem. We usually notice the symptoms before we notice the tiny mites. Look for a webbing along the branches. From what you have described this could be a possibility. These evergreens are very cold-tolerant so the temperature should not be a factor. When we see yellow foliage on evergreens it is usually on the inner part of the plant. This is a normal shedding process they go through each year allowing more room for new growth. Yellowing on the tip is certainly more of a concern. A positive diagnosis is the only way to help prevent future damage, so take a sample to the garden center where you purchased it; hopefully they will have a knowledgeable staff that can help or you can always go to your County Cooperative Extension Service. The horticulture agent will be able to give you a more definitive diagnosis. It could also be a moisture issue. I think it would be too soon to show any signs of nutrient deficiency, which can be a common issue with container plants. Since the temperatures are not hot yet, these plants will not need to be watered more than once a week. As the temperatures rise you will need to increase your watering routine. Make sure the soil is never sopping yet. It should be allowed to dry out before adding additional moisture. You may also check the drainage hole to make sure it is not blocked.