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O ne way of over-caring for our plants is over-fertilization. Fertilizer is often misunderstood and mis- used. Fertilizer is not food. Plants produce their own food in the form of sugars through photosynthesis. The min- erals supplied by fertilizer provide the ingredients needed for photosynthesis. When minerals are lacking, fertilizer can be added to maintain an adequate supply. If there are enough minerals available, maybe they're simply locked up by the soil. Some minerals are released easily from the soil to the plant's roots while others hold on for dear life. Usually this happens because of a pH issue relating to soil type. Clay soils are higher in pH and normally hold onto minerals tighter where sandy soils are lower in pH and release them much easier. The best way to neutralize the soil in both cases is to add organic matter (com- post, etc.). The first place to start before fertilizing is with a soil test. This way we know if the soil is either lacking minerals or they are sim- ply locked up. A soil test will tell you what type of soil you have, the major mineral content (N, P, K), along with pH and organic matter. You can ask for a more detailed test if you want, but it is more expensive. But the more we know the better. Once you have your soil test in hand, bring it to a reputable garden center. They can help decipher it and make corrections if needed. Most times the addition of compost is all that is needed, but sometimes we do need to correct an issue. So, where do we go wrong when fertiliz- ing? First, we assume plants need fertilizer. In most cases, that isn't the case. Over-fertiliz- ing can cause mineral and salt buildup in the soil, which can burn and injure root sys- tems. You are more likely to do this with synthetic fertilizers than organic forms. And what happens when plants start to look bad? We decide they must need more fertil- izer and we injure them even further. Getting it right The right fertilizer for the right plant is crucial. Slow-feeding perennial plants, including trees and shrubs, like an organic, slow- release granular fertilizers with lower nutrient numbers like 4-5-6. Heavy-feeding annual plants like higher numbers such as 20-20-20 found in water-soluble synthetic fertilizers. There is no one fertilizer that is good for all plants. Turf grass also likes high-nitrogen for- mulations like 20-0-0. This is where we sometimes get into trouble. This higher nitrogen in turf fertilizer can burn the root system of other plants. I recommend fertilizing the lawn once a year in the fall. That is all that is really needed. We over- fertilize our lawns way too much around here. Another issue is fertilizing plants when they are under stress. This can be from drought, injury, insects, disease, etc. This actually creates more stress. Fertilizer is not a cure for bad-looking plants. It is simply basic nutrition. Also, newly planted plants shouldn't be fertil- ized until after they establish themselves, normally three years. If you do, you are forcing growth on a plant that has a small root system and can't support this growth. Container plants and baskets are differ- ent creatures and need more fertilization. But over-fertilization can also be a prob- lem. Over-fertilizing, without flushing, causes salt build up which damages roots. Flushing is watering with clear water to wash out the salts on a regular basis. Over- fertilizing can also cause excessive growth, which the roots cannot keep up with properly. So before fertilizing, get to know your soil and plants and fertilize accordingly and not haphazardly. Happy gardening! (Michael Timm is chief horticulturalist for Ebert's Greenhouse Village in Ixonia.) APRIL 2023 HOME 3 Loving our plants to death Over-fertilizing or using improper fertilizer MICHAEL TIMM Photos by Michael Timm Just looking at the fertilizer packaging can help get the right type of soil, Michael Timm writes. Before heading to the garden center, he says gardeners should get a soil test and bring the results with them. Often soil doesn't even need fertilizer or not as much as you might assume, according to Timm.

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