WATER MEDIA

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WATERMEDIA NUTRITIONIn Potted
PlantsJohanna OosterwykUW - Horticulture
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WATER
Transpiration
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Water Quality
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pH
Most potted plants prefer a water source with pH
between 6.0 and 7.0
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Electrical Conductivity (EC)
Measure of soluble salts Doesnt say which salts
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Alkalinity
Measure of carbonates and bicarbonates in
water In WI this is often Calcium Carbonate
(CACO3)
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Contaminants
Fluoride Nitrates Pathogens Other Soluble
Salts
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Root Health
Healthy roots on a Chrysanthemum cutting
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Ensuring water quality

• Test for
• pH
• Alkalinity
• EC
• Nitrates
• Other Soluble Salts

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Water Source
Local ground water (wells)
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Water Source
Local surface water (local ponds, reservoirs,
lakes and steams)
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Water Source
Municipal Water Systems
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Water Source
Rainwater Retention
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Water Treatment
Reverse osmosis
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Water Treatment
Filters
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Water Treatment
Softeners
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Water Treatment

• Bottled water
• Spring
• Distilled

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Water Treatment
Leaching
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Chief cause of death overwatering
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Soil column in a pot
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Do try this at home
Air/Water Balance in Media
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Watering Recommendations
Indoors
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Watering Recommendations
Outdoors
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MEDIA
Air
Moisture
Support
Nutrients
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Characteristics of Good Pot Media

• Structure
• Promotes drainage and lifespan of media
• Porosity
• Allows for drainage
• Water Holding Capacity (WHC)
• Retains moisture
• EC and Cation Exchange Capacity (CEC)
• Holds nutrients available to plant
• pH
• Nutrient availability

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Garden Soil
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Garden Soil
This is not it
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Components of Potting Mixes

• Organic Matter
• WHC
• CEC
• Structure
• pH
• Particulates
• Structure
• pH
• Additives
• Wetting Agents
• Fertilizers
• Fungicides or pesticides

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Organic Matter
Peat Moss
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Organic Matter
Coconut Coir
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Organic Matter
Composted Fir Bark
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Organic Matter
Compost
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Particulates
Perlite
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Particulates
Vermiculite
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Particulates
Pumice
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Particulates
Horticultural Grade Sand
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Particulates
Parboiled Rice Hulls
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Additives
Wetting Agents
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Additives
Fertilizers
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Additives
Pesticides
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Premade Mixes
sphagnum peat moss forest products compost coir
pith fiber perlite a wetting agent fertilizer
55-65 Canadian sphagnum peat moss composted
softwood bark perlite, a wetting agent
fertilizer
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When you Buy Potted Plants
Check for contracted media
Check for rootbound plants
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When to change Media

• When the plant becomes rootbound
• When Organic Matter in media degrades
• When media EC becomes too high
• If your plant is staying too wet or dry
  regardless of how you water

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NUTRITION
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Growing Plants Need Food

• Not all plants are growing all the time.
• Many are slow growers, or may be resting
• Most commercial media have some fertilizer charge

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Fast growing (heavy feeders)
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Slow growing (light or non-feeders)
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Special cases
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Resources

• West Madison Agricultural Research Station
• www.cals.wisc.edu/westmad/index.html
• UW Soil and Plant Analysis Lab
• uwlab.soils.wisc.edu/madison/
• Plant Root Zone Management Handbook
• North Carolina Commercial Flower Growers Assoc.