We Have Had Our Knock Out Roses For Four Years….
Linda Asked
We have had our Knock Out roses for four years. I believe I over-fertilized them last year and want to know what I should do?
The Gardener’s Answer
Hi, Linda in Tennessee: It is easy to over-fertilize our plants. We want them to be beautiful and bloom as much as possible so we feed them, and as a result they produce abundant blooms and everyone is happy. This is all fine and dandy until we get carried away with the fertilizer and it has the opposite results of what we were hoping for. Over-fertilizing can be very detrimental to plant material, causing them to be stressed. Initial signs are wilting and leaf curl of the foliage, tip burn, and discoloration. A once-healthy green plant may turn bluish/green or yellow at the edges and may have a different texture than it once had. Nutrient toxicity is harmful to our plants, which is why it is so important to follow recommended application rates for the product you are using, either granular or liquid. For now you might want to have your soil tested to see what the N-P-K levels are so you know where to start for this growing season. If your roses are too far gone, you may need to pull them out and replace them. It is always best to not fertilize new plantings for the first year. They should become established in the soil that exists naturally. It will give you a healthier plant in the long run. You may want to take a sample of your roses to your favorite garden center to have a horticulturist take a look, or you can always take a sample to your County Cooperative Extension office. This is also who you can contact to have your soil tested.
