cause of yellow bottom leaves on roses

Asked August 9, 2016, 3:17 PM EDT

We have Knock-out roses that were planted this Spring. In the last month most of the bottom leaves have turned yellow. Other plants in the same beds are fine. Beds are in full sun on E/ SE side of house. Are we watering too much, or too little ? We have sandy soil, covered with mulch and have been using a soaker hose . With the heat we have been running the hose for 80 minutes every two days.

Kent County Delaware plant disease roses knockout roses rose

1 Response

Hello,

Without seeing the plants, what you describe is most likely stress from transplanting and environmental stress such as the heat. It is normal for roses to lose some lower leaves in mid-summer, after the flush of bloom in June.

I would recommend watering every three or four days if there is no rain. The soaker hose is a good idea, to avoid water on the leaves, but 80 minutes sounds a bit long.The rule of thumb says an inch of water once or twice a week, but that is so difficult to measure.

It often takes plants a year or two to get established. Do not fertilize during the first six months to a year, as the plants cannot take up the salts until they have developed more extensive root systems.

Thank you for contacting Cooperative Extension.