Red Raspberry (Rubus idaeus) is a perennial crop.  There are two types of canes in red raspberry plants. Primocanes are first year canes. Some varieties of raspberries produce berries on primocanes and are commonly called fall-bearing or primocane-fruiting raspberries. Other types of raspberries do not bear fruits on the first-year vegetative canes, but they develop flower buds that overwinter and produce berries in the subsequent season. These overwintered buds-bearing canes that will flower and fruit in the subsequent season are referred to as floricanes. After harvest, floricanes are commonly removed and the next cycle of primocanes develops. Sufficient nutrient availability during growth stages of red raspberry is essential for plant vigor, yield, fruit quality, fruit maturity, and sustainable plant health. Nutrient cycling in the soil-plant-air system in perennial plants is complicated and sufficient nutrients should be available before rapid nutrients uptake and requirement growth stages.   

Everbearing raspberries before pruning. Photo by dmp2006

Like any other plants, red raspberry requires seventeen essential nutrients, nine macronutrients (hydrogen (H), carbon (C), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)) and eight micronutrients (iron (Fe), copper (Cu), boron (B), manganese (Mn), molybdenum (Mo), zinc (Zn), chlorine (Cl), and nickel (Ni)). The three most abundant essential nutrients (hydrogen, carbon, and oxygen) are predominately obtained from water and carbon dioxide in the air, while all other essential nutrients are taken up by plant roots from the soil. When the soil is unable to supply sufficient nutrient(s), fertilization is needed for optimum yield and quality of berries. Nutrient application should be based on soil and plant analyses and grower experience in their raspberry production system.

Bowl of Heritage raspberries. Photo by dmp2014.

Plant tissue analysis is an excellent method for growers to monitor nutrient sufficiency levels. Timely plant tissue analysis is helpful for detecting nutrient deficiencies in perennial fruits before visual deficient symptoms show up and minimize loss of yield and quality. Nutrient uptake, accumulation, and relocations in plants are complicated in perennial crops like raspberry, therefore, tissue testing should be based on a consistent sampling in the plant growth stage and time of the day, selection of the appropriate plant part, and the recommended sufficiency levels (please contact UConn’s Soil Nutrient Analysis Laboratory, for the recommended sufficiency levels) for comparison.

Red raspberry growers are recommended to sample and test leaf tissue from all fields annually.

  • When to sample: Tissue samples should be collected when nutrient concentration is stable, thus, collect red raspberry leaf tissue mid-summer.
  • What part of a plant to sample: Collect approximately 50 of the 4th fully expanded leaves located about 12 inches from the tip to make a composited sample for tissue analysis. Collect leaves that are free of disease or other damage. A single composited sample should not represent an area of more than 5 acres. Do not mix leaves from field locations with different soil types or management histories. Separate samples should be taken for different soil types, management histories. For diagnosis purposes, separate samples should be taken in healthy and unhealthy plants.
  • How to handle samples: Put a composited sample consisting approximately 50 leaves in a paper bag, clearly labeled the bag, and send it to a local laboratory providing leaf tissue nutrient testing services as soon as possible. Conventional laboratory plant tissue nutrient analysis procedures are shown below.
Schematic flow chart of conventional plant tissue nutrient analysis procedures.

How to guide fertilization with laboratory results?

Compare the laboratory results to the recommended leaf tissue sufficiency levels shown in Table 1. If laboratory results are below the recommended sufficiency levels, fertilizer applications would typically be increased. If laboratory results are within the recommended sufficiency levels, continue with the current fertilization regimes. For recommended sufficiency levels please visit the UConn Soil Nutrient Analysis Laboratory or refer to University of Vermont Extension publication at To assist with interpretation of tissue analysis data, record keeping is recommended. In addition to keep records of tissue testing, soil testing results, weather (daily rainfall and temperatures), disease problems, nutrient application rates, form and timing, plant growth (such as cane number and height), yield, leaf color, and fruit quality are also helpful in estimate nutrient requirements in various crop yield potential situations.

Table 1. Recommended leaf tissue nutrient sufficiency levels for red raspberry.

NutrientSufficiency level
N (%)2.3–3.0
P (%)0.19–0.45
K (%)1.3–2.0

Dr. Qianwen Lu, Graduate Research Assistant, University of Connecticut