Question
Dear Jim,
 I have a Cornus florida and a Cornus kousa that were planted last summer. What time of year should they be fertilized and how often? I live in New Jersey.  

Answer
Over fertilization is a frequent killer of young dogwoods. Its best not to fertilize the first year -- allow the root system and the foliage to reestablish a proper balance. A young 6 foot dogwood can be fertilized  in February and mid-June.
During the summer months the growth rate of most plants slows down, and when plants are not actively growing, they need very little nitrogen. Although not vigorously putting on new growth, many plants such as Dogwood Trees, Rhododendrons, and Azaleas are quietly working to produce flower buds for next year. Annual and perennial flowers are also busy making new flower buds.

To encourage flower bud production you can apply a fertilizer that contains a small percentage of nitrogen, a higher percentage of phosphorous, and a little potassium. I recently purchased a liquid fertilizer with an analysis of 5-30-5, ideal for flower production. Because the product is sold as a bloom producer, the manufacture also added a little chelated iron, manganese, and zinc, all good for your plants as well.

Most garden centers and discount stores carry similar products.

I chose a liquid fertilizer because liquid fertilizers are absorbed both through the roots and systemically through the foliage, so they work quicker. I used a sprayer that attaches to the end of the garden hose to apply the fertilizer, but do not use the same hose end sprayer that you use for lawn fertilizers. There could be residual weed killer still in the sprayer.

About those hose end sprayers. I purchased one that is supposed to automatically mix the proper ratio for you. I used it to apply a general insecticide, and it worked, but it sure seemed like I went through a lot more insecticide than I needed. When I used it for the fertilizer the screen on the little pick up hose inside the jar kept getting clogged with the tiny solids in the fertilizer. I recommend using a solution of one part liquid fertilizer to one part water in the sprayer jar, and applying at a heavier rate. Watch the liquid in the sprayer jar, and if it isn't going down remove the lid and clean the little screen by spraying it with water from the garden hose.

Read the application instructions on the container to determine how much fertilizer to apply, and how often. A fertilizer high in phosphorous will increase flower production. You will see a difference.

Remember the golden rule of applying fertilizers. "Not enough, is always better than too much."