EHS 230 Final
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- Really is medium (media is plural)
- a material used for rooting or supporting the roots of plant. Media are sub classified by function as rooting media, potting media, seeding media, and so on.
- Mixture of many ingredients, some manufactured and some naturally occurring
Potting Media Advantages
- Advantages over most pure soils:
- -made up of materials that can create large pore spaces so they are less likely to pack around the roots of plants
- -have loose structure that drains well
- -usually free of disease organisms, weed seeds, and insects
Potting Media Components
- 1.Organic, plant derived material: it is water-absorbing and water-holding capacity will be great
- Cation-exchange capacity: nutrient holding capacity
- 2. Coarse aggregate: improve the drainage of the medium
- 3. soil: used to hold and supply nutrients and acts as a reservoir of water in addition to the organic soil.
Macropore vs micropore spaces
- Micropore: a small pore space found between minute particles such as clay
- Macropore space: large pore space found between large particles or aggregations of soil particles
- any of several bog plants, particularly sphagnum moss, that are harvested, dried, and used as components in growing media or for soil amending
- main ingredient in many prepackaged houseplant mixes, often 50% of the volume
- alternatives to Peat Moss
- outer husk of the coconut and a byproduct of the coconut industry
- fibrous and does not have a water-repellency problem
- expands when wetter
- component of prepackaged houseplant media
- derived from plants and is made up of partially decayed leaves and twigs.
- may be used is premixed potting media in addition to or as a compete substitute for peat moss
- natural product in the decomposition of leaves
Humus Peat or Muck
- a soil type
- composed largely of organic material in the form of highly decayed vegetable matter such as leaves, stems, and roots
- Shredded or ground bark is used occasionally as an organic potting-medium component.
- Fir, redwood, pine, hemlock, and oak
- Less water-holding capacity and higher pH
Hydrating Gel Granules
- synthetic acrylic copolymer granules or spikes, occasionally are a component of potting media
- absorb more than 100 times their weight in water
- Sand: naturally occurring material used occasionally in premixed potting media (heavy)
- Perlite: made by heating volcanic rock until it expands and then grinding the resulting material into irregular chunks. Does not hold appreciable amounts of water or nutrients
- Vermiculite: made by heat expansion of mica, spongy real, pH of 7.0 to 7.5, contains potassium and magnesium
- Scoria or Lava Rock: natural volcanic rock
- Charcoal: absorbs and holds odors, toxic pesticides, and undesirable chemicals, not practical
- well-balanced combination of the basic soil particles-sand, silt, and clay.
- rich in topsoil
- holds water well, does not pack or crust when dry, and be easily crumbled
- composed largely of tiny plate-like particles that pack together closely, forming many micropore spaces
- very water and nutrient retentive but poorly aerated
- if sandy enough it may be a substitute in part for the coarse aggregates
- create relatively small pore spaces
- has a floury feel when dry and poor aeration
- has neither the nutrient-holding capacity of clay nor the coarse aggregate function of sand soil
- should not be used in media
- counteracts the acidity of the organic component to give the media the slightly acid pH at which most tropicals grow best
- contains quantities of calcium and magnesium needed for growth
fertilizer mixed into the potting medium before use
- Dissolving Powder Concentrates: powder fertilizers designed to be mixed with water are one fertilizer form. available immediately for uptake by plant roots
- Tablets and Spikes: as a plant is watered, these solids break apart, dissolving their nutrients into the water as it flows down the roots
- Liquid Concentrates: dissolved powders in which water has been added; mix in water instantly
- Ready-to-Apply Liquids: poured directly on a plant in place of water, low nutrient concentration
- Encapsulated Slow Release: can be worked into the medium at planting with equal effectiveness made possible by moisture present int he medium seeping in and out of the beads
- Granular Slow Release: one compound releases nutrients immediately whereas the other must be chemically broken down.
Fertilizer Frequency and Rate
- most important facts to remember when fertilizing a plant is not to increase the fertilization rate or frequency unless you are sure that the plant is suffering from nutrient deficiency.
- never apply fertilizer to a dry medium
- fertilizing should not be considered a cure for plants that are declining from an unknown cause.
- are extracted from plant or animal sources instead of being obtained by mining or chemical reactions
- fish emulsions, seaweed extracts, and manure formulations are some type of organic fertilizers
- contain the same macronutrients
Medium and fertilizer related indoor plant problems
- Compaction: is the excessive packing or settling or potting medium
- Poor Drainage: if a layer of gravel or other coarse material was put in the bottom of the pot at transplanting, this could be a problem
- Water Repellency: water applied to the medium will run through or down the sides of the shrunken soil mass, with little being absorbed
- Unsuitably High or Low pH:pH can change because of pH in water. if too acidic ammonia should be used to raise it
- results from excess concentration around roots of compounds called fertilizer salts.
- this does not permit entry of water into the roots and creates drought condition (wilting)
- will not recover immediately when watered
- Large amounts of water should be poured through the medium to flush the fertilizer salts out
- shows up first as yellowing of older leaves but then yellows both older and younger leaves
- small new leaves and thin stems
stunting of growth and the production of undersized new leaves.
- appears on older leaves first, frequently as a browning of the leaf margins and tips
- areas between the veins may also be affected
- occurs frequently in acid-loving houseplants
- yellowing between the veins of the young leaves
- yellowing will eventually include the entire leaf known as iron chlorosis
- corrected by temporarily by foliar sprays of micronutrients ad permanently corrected by changing the pH of irrigation water
Fertilizer Salt Deposits
formed when fertilizer salts dissolved in water move to the outside of the soil ball in response to evaporation of water. The water leaves as vapor, but the salts remain
One of the main causes of houseplant failure
- improper lighting
Pathways of water loss in Houseplants
- Transpiration: the loss of water from a plant usually through leaves, in vapor form
- Evaporation: water leaves the area where it is concentrated and moves as vapor into the drier adjacent air. humidity and temperature cause changes in evaporation
- Bottom Drainage: drainage of excess water out the bottom of a pot is the third pathway of water loss. amount of water retained depends on the ingredients of the media.
- the smaller the pot=more frequently it needs to be watered.
- the larger a plant is in relation to its pot, the more frequently it will require watering
Ways of testing soil moisture
- Touch method
- Color method
- Weight method
- Commercial Moisture Sensors
- Top Watering:easy and completely satisfactory for almost all indoor plants
- Botton Watering: only be used on plants in pots with drainage holes. for plants whose leaves are susceptible to spotting from water
- Submersion Watering: is only used for pots with drainage holes and for the same purposes as bottom watering.
- Wick Watering: for plants that must have constant moisture and complete drying will cause death
- Shower Watering:
Identifying the affected plant
first step in diagnosing a plant problem is identifying the plant that is affected
- holes in leaves or severed stem
- plant should be inspected under the leaves and near buds and feeding sites
- Grubs and Borers
- Leaf Miners
- Snails and Slugs
- Feed on the sap by inserting their mouthparts into the phloem or by grating a small area and feeding on sap oozing from the wound
- Aphids:produce honeydew
- Scales and Mealybugs
- Mites (spider mites)
insects can cause abnormal swellings known as "galls." They are analogous to tumors and made up of large numbers of non differentiated cells that have no useful function.
- microscope or nearly microscope worms
- most are soil dwelling, burrowing into roots and decreasing root growth
- results in yellowing and general lack of vigor
Four categories of microorganisms
- Viruslike organisms
Single or multicelled organisms that lack chlorophyll
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