Slow release nitrogen lawn fertilizers can usually be used safely on almost any plant on the property. However, lawn fertilizers tend to have an emphasis on nitrogen, even if it is a slow release form. Therefore, for fertilizing ornamental plants around the landscape we are better to use what is called a "balanced" general fertilizer. In these cases, the nitrogen, phospherous and potassium are much closer in terms of their percentages in the product. You will see NPK numbers such as 5-10-5 or 5-5-5.