Roses Not Doing Well......Maybe They Need Citrus Food???

Soils of the Las Vegas Valley vary considerably in their physical and chemical properties, therefore growing plants for the garden or the landscape can often be challenging.   With many different soil problems facing the gardener, deficiencies of the essential plant nutrients or elements is the most common across the Las Vegas Valley.  Plants require sixteen essential elements for proper growth and development (17 or 18 elements when referred to as ‘beneficial elements’ rather than ‘essential’).  The elements may be divided into three groups based on the quantity each is used by plants.  The three groups are primary, secondary, and trace.  The primary elements nitrogen, phosphorus, potassium, carbon, hydrogen, and oxygen are used in the largest quantities followed by the secondary elements calcium, magnesium, and sulfur which are followed by the smallest quantities or trace elements of iron, zinc, copper, manganese, molybdenum, chlorine and boron.  It’s important to note that although nearly all plants require the same 16 essential nutrients or elements, they don’t always require them in the same quantities or more importantly, in the same proportions.

In general, in uncultivated Las Vegas Valley soils we find deficiencies consistent with the trace elements iron, zinc, copper, and manganese; however, availability of the primary elements nitrogen and phosphorus will vary from area to area with the exception of the primary element potassium which in most cases is found in relatively  high concentrations.

By providing the nutrients that are deficient in the soil, through the application of fertilizers, we can often improve growth and development of our garden and landscape plants.  Providing proper nutrition will also often increase resistance to insects, disease, drought, etc.  Determining which nutrients are deficient requires laboratory testing of the soil and plant tissue.  This process is often done with commercial landscapes; however, is rarely done with residential landscapes.  For this reason, fertilizer manufacturers produce fertilizer formulations with varying proportions of the primary elements nitrogen, phosphorus, potassium, and may also include secondary and trace elements for specific plants or plant types that are growing in average soils.  Thus, on the nursery or garden center shelf we find fertilizers identified as ‘Tomato Food’, ‘Rose Food’, ‘Citrus Food’, ‘Palm Food’, ‘Turf Supreme’, etc.   On the front of the container of each of these fertilizers is three numbers each separated by a hyphen        (14-7-5).  Each number represents a percentage by weight of nutrient in the container.  In this example it equals 14% nitrogen, 7% phosphoric acid (phosphorus) and 5% potash (potassium).

Unfortunately, Las Vegas soils are rarely average.  If your roses are not responding to the ‘Rose Food’ (6-12-4) and soil and plant tissue tests indicate you need twice as much nitrogen, half as much phosphorus, and twice as much potassium then perhaps you need to try the ‘Citrus Food’    (14-7-7).

Landscape professionals select specific fertilizers based on laboratory soil and plant tissue testing, plant requirements, and field observations.    Such fertilizers are referred to as ‘site specific’.  Utilizing site specific fertilizers will meet plant requirements for proper growth and development while keeping costs at a minimum and protecting the environment. To the landscape professional titles such as ‘Tomato Food’, ‘Citrus Food’, ‘Turf Supreme’ have little value.