KSU Viticulture
Water and Nutrition



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Water and Irrigation

Grapevines lose lots of water by transpiration and evaporation during their growing season since they have large canopies with big leaves and there are large spaces between vines and rows.  Developed grapevines, however, have large root systems to absorb water from soil, so they can survive regions with annual rainfall ranges from 270mm to over 1100mm (11 to 44 inches). For a mature vineyard in Kentucky, irrigation is not extremely necessary even under very dry conditions. Newly planted grapevines, however, do not have well developed root systems and therefore need to be watered frequently for the first couple of years. Also, vineyards located on deep slopes or stony soils should think about installing a irrigation system, although these sites should be avoided at site selection.

Water is held in the soil as films around soil particles and temporary in pores so irrigation strategy should take soil characteristics into account. For example, a sandy soil holds only about 1/3 of the water that clay or loam soil does. 

Water stress affects vine growth. Vines at different development stages may handle different degrees of water stresses. Four phenological intervals between budburst, flowering, veraison and harvest are usually considered.  Vines from budbreak to bloom are sensitive to water stress, although in Kentucky it is not a problem since enough rainfall usually takes place. During this time, however, overhead sprinkling can help prevent frost damages; vines from flowering to veraison can be subject to water stress since less rainfall might happen and the water stress can lead to poor fruit setting and small berries; vines from veraison to harvest can withstand a considerable amount of water stress, which may also help with sugar accumulation; after harvest, vines are usually ok without irrigation unless extreme drought weather occurs. 

Irrigation type: if irrigation is considered for a new vineyard, water source, lines, control system and electrical requirements should be considered during site preparation. I strongly recommend an overhead sprinkling system for young vines, and more important, for frost protection. It also can be used for reducing sunburn and leaf temperatures during hot and dry seasons. Drip irrigation is probably the most cost effective system for young vines (and old vines), it can also be used for fertilization. For temporary irrigation (can be "permanent" for the first 2-3 years), T-tapes will be a very good system, which is easy to set up, control and cost effective. 



The essential elements for vine growth and development

When an element is essential, it means vines cannot finish their life cycle without it or a deficiency can be disastrous. Potassium, nitrogen, calcium, magnesium, sulfur and phosphorus are major elements (macronutrients) occurring at 0.2 to 3%  of dry weight; iron, manganese, molybdenum, copper, zinc and boron are trace elements (micronutrients) occurring at 0.5 to 150 ppm (parts per million). Some information on vine nutrition is listed in the following table. Please note that the function of an element is not provided.


% of dry weight

Amount per 1000kg  grapes

Deficiency symptom

Range in petiole




Nitrogen (N)





Reduced vigor: smaller leaves and shoots, all-over yellowing leaves and other green tissues

0.22-0.53 NO3 (%) or 500-1200 NO3-N mg/kg

Young vines: apply 3g of actual nitrogen per vine per month.
Mature vines: 20-60kg/ha before bloom annually. Can also foliar spray 5g urea/litre. 

Increase in vigor: reduction in fruit set and bud fertility; reduce cold hardiness


Phosphorus (P)





A gradual reduction in shoot growth. Basal leaves may pale or turn yellow and fall before flowering. 0.2-0.46 P (%) Preplanting: deep place 0.5-1.0 tonne  superphosphate/ha.
Mature vines: apply 0.5-1.0 tonne superphosphate/ha once every 3 years.
Phosphorus is relatively immobile in the field. Applying to the root zone will help. 

Potassium (K)


up to 3%



Symptom shows first in the older leaves. Older leaves of white variety become yellow near the margin and this chlorosis extends inwards the center of leaf, can become acute marginal burning. Red cultivars show red rather than yellow coloring prior to the marginal burning. Bunches are small and tight, berries ripen unevenly.  

>1.5 (%)

<0.5% deficiency


Can add 1-2 tonne/ha into planting lines before planting; When needed, young vines 40g/vine/month; old vines, 1-2 tonne/ha of K2SO4. Foliar spray of KNO3 at 10-20g/L can be used.

High K in juice affects wine quality since it increases pH.
For N,P,K addition, the cheapest mixed fertilizer can be used, e.g., 14-14-14 lawn fertilizer.
Magnesium (Mg)

50-150 ppm

  Yellowing between veins of older leaves; red cultivar shows a red pigmentation in these vein areas. >0.3% Use dolomitic limestone (9% Mg) in acid soils or add magnesium sulfate (19% Mg) to soil or foliar spray (20g/L)  
Iron (Fe) 50-150 ppm   A diffuse yellowing of young leaves and new growth, veins may remain green if deficiency not so acute.   Not easy to correct since the form of Fe2+ is the active form in plants. Apply iron sulfate or some iron chelates. Foliar spray can be used. Lime soil causes Fe deficiency, especially for cultivars of Concord blood.
Manganese (Mn) 50-150 ppm   A yellowing occurs between the main veins in broad bands on older leaves.  


Foliar spray of 1.5 g/L manganese sulfate Some fungicides (Mancozeb) contain Manganese

Zinc (Zn)



  "little leaf" symptom and stunted growth: the small leaves have a detailed mottling between the veins and have a widened petioar sinus where the leaf stalk connects to the leaf.  


Foliar sprays of zinc oxide (2g/L) or zinc sulfate (1g/L). Some fungicides (Mancozeb) contain Zinc.

Boron (B)



  Reduced fruit set, more seedless berries; death of shoot tips and yellowing between veins of recently matured leaves  


Foliar spray before bloom (3b/L).  
Copper (Cu) 0.5-40ppm   Not usually seen since copper containing sprays usually take place. >6 ppm    







































Determining the need of Fertilization

Analyze your soil: Soil samples should be collected before planting. Contact your county extension agent for more information.

Tissue  analysis: Petioles and blades have been used to represent the nutrition status of vines. California grape growers use petioles while the Australian use blades. Petioles can be sampled at two different times during the growing season.  Bloom-time petioles are the best indicators of zinc and boron status, while sampling at veraison will provide more accurate readings of potassium and magnesium levels. But practically, only do sampling at full bloom (70% capfall) for petiole analysis. If you want to do blade samples, the veraison stage will be the best time. When sampling, collect about 100 petioles or blades from basal leaves opposite to bunches, early in the morning; dry them at room temperatures or store them in the refrigerator before mailing them to the laboratory. Different cultivars should be separated. TOP

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Updated August 13, 2007