Grower FAQ

What is the pH of Fafard mix and how is it affected by plant culture?
Should I avoid perlite because of fluoride toxicity problems?
Does bark tie up nitrogen?
How long does the fertilizer starter charge last and does it have trace elements?
What is in Fafard mixes?
My water pH is very high. Will this affect the mix and the crops grown?
The mix does not wet. What should I do?
I have weeds everywhere. Where did they come from?
Why are my plants yellow?
The leaves on my plants are twisted and abnormal. What is the problem and how can it be corrected?
Does Fafard have a mix for certified organic growers?
I have green scum growing on the surface of the mix. When the mix dries, it turns brown and then water will not penetrate. What causes this?
Are Fafard bark mixes disease suppressive? Other companies make these claims.
Isn’t there a shortage of peat lands in Canada? Isn’t peat harvesting depleting the wetlands?
What is the CSPMA Preservation and Reclamation Policy?
Is peat moss a renewable resource?
Where can I find more information on the environmental concerns with peat moss?
Does a potting mix have a shelf life?
Is there an advantage to using some coir in the mix?
How long can I store a mix that contains a controlled-release fertilizer (CRF)?
Why is the mix pH so low when tested fresh from the bag?

What is the pH of Fafard mix and how is it affected by plant culture?
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Fafard mixes are limed so that two or three days after watering in, the pH will be between 5.5 and 6.5. However, the amount of lime in the mix is only one of several factors that affect media pH as the crop is grown. Water alkalinity level and type of fertilizer used also have a major influence on mix pH. Alkalinity, a measure of a water's ability to neutralize acid, is caused by the bicarbonate ion. Highly alkaline waters can cause mix pH to increase over time with high levels causing a greater degree of increase than lower levels. While moderately alkaline water may not change media pH, low alkalinity can actually cause mix pH to decrease. Water alkalinity levels can easily be determined through water analysis. Fertilizer also affects media pH. Fertilizer that contain ammonium or urea (20-20-20, for example) have an acidifying effect, causing a decrease in pH after repeated use. Fertilizers that contain little or no ammonium or urea (like 20-10-20) are not strong acidifiers. Some materials like 15-0-15 have a basic effect, resulting in a pH increase. The label of soluble fertilize bags will always show the material's potential acidity or potential basicity. This measure can be used to judge a fertilizer's potential to change growing-mix pH. With controlled release fertilizers, the potential acidity or basicity is not shown on the bag. If the fertilizer is formulated with ammonium or urea or is sulfur coated, the material will have an acidifying effect on mix pH. The amount of lime in the mix is not always the main factor controlling mix pH. Two other factors — the alkalinity of the irrigation water and the type and concentration of fertilizer used — also have a major influence on pH. When managing growing-mix pH, all three factors must be considered.

Should I avoid perlite because of fluoride toxicity problems?
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While some perlite sources do contain fluoride, perlite is rarely the sole cause of toxicity problems because fluoride is quickly leached to safe levels. Chronic fluoride toxicity problems are almost always caused by persistent F sources like the water supply or contaminated fertilizer. If plant roots are continuously exposed to F levels more than 0.5 ppm fluoride, sensitive plants like lilies, dracaena, and spider plants are subject to damage. If fluoride toxicity is a problem, identify all F sources in the growing system. If the water contains too much F, all other fluoride sources including perlite should be eliminated. However, the mere presence of perlite will not trigger toxicity problems if there is no persistent fluoride source.

Does bark tie up nitrogen?
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All organic mix components undergo natural decomposition. Bacteria and fungi are responsible for this process. The micro-organisms consume nitrogen along with the organic material and the nitrogen becomes “tied-up” within the cellular structure. In the pot, these micro-organisms compete with the plant for nitrogen. Mix made with readily decomposable organic material can support a large population of micro-organisms. Bark fresh off the tree is subject to rapid decomposition. To compensate for this, soil producers age or compost the bark. The resulting bark is resistant to further rapid decomposition. The use of aged or composted bark in a mix supports a much less active population of micro-organisms than fresh bark, consuming or “tying up” less nitrogen. Properly aged or composted bark ties up only slightly more nitrogen than peat moss.

How long does the fertilizer starter charge last and does it have trace elements?
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Like most commercially prepared growing mixes, Fafard mixes are formulated with an N-P-K plus trace-elements starter fertilizer. This fertilizer is water soluble, not granular, and is sprayed onto the mix during the mixing process. This spray application assures uniform coverage. The starter charge is not intended to be a long-term fertility source. Instead, it is used to provide nutritional balance at planting. Being water soluble, this starter fertilizer has limited longevity because it is easily leached from the mix. Watering in with a large volume of water can easily leach most of the fertilizer from the mix. Even with lighter watering, most of the fertilizer can be leached after two or three irrigations. During the initial watering, use care to apply the same volume of water to each container. Failure to do so can result in uneven leaching of the starter charge and subsequent nonuniformity of initial growth. While the starter charge contains small amounts of iron, manganese, copper, boron, zinc, and molybdenum, supplemental trace elements must be provided through the fertility program. Fafard mixes also contain dolomite limestone and gypsum as sources of calcium, magnesium, and sulfur. Supplemental applications of these three elements may be required. Because of the starter fertilizers limited longevity, Fafard mix users should begin fertilizing very soon after planting. When to begin fertilizing depends on the crop. With crops considered to be medium to heavy feeders, many growers water in with a soluble fertilizer. If watered in with clear water and not heavily leached, fertilization can be delayed to the second watering. With light feeders or salt sensitive plants like New Guinea impatiens, water in with a large volume of water to remove most of the starter fertilizer from the mix. Then, begin a light fertilization during the second or third watering. When using Fafard growing mixes, remember that the starter charge is easily leached and is not a long-term source of fertility.

What is in Fafard mixes?
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Depending on the formulation, a Fafard mix could contain Canadian sphagnum peat moss, processed pine bark, perlite, vermiculite, or sand. Unless otherwise specified, all Fafard products contain a water-soluble starter fertilizer, wetting agent, and dolomite limestone. Growers can also specify custom-component formulations, customized limestone additions or various controlled-release fertilizers.

My water pH is very high. Will this affect the mix and the crops grown?
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Water pH is a measure of solution acidity or basicity. It is an easy assumption that the pH of the irrigation water can affect the potting mix pH. However, water pH alone has little impact on the mix. Instead, another property of water, the alkalinity level, affects mix pH. High pH water can, but does not always, have high alkalinity and should prompt a complete water analysis to determine alkalinity level. Irrigation water high in alkalinity can induce rising growing mix pH, resulting in trace element deficiencies in pH sensitive crops like petunia and calibrachoa. Considered as a single factor, high water pH is a bigger factor when preparing pesticide solutions rather than its effect on the mix. Low pH water can also cause problems. The reduced bicarbonate concentration in low pH water can cause declining potting mix pH, increasing the potential for trace element toxicity problems in sensitive plants like geranium and marigold.

The mix does not wet. What should I do?
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Mix that is too dry may be hard to wet even if it contains a wetting agent. Bagged mix can dry out during storage and pre-filled pots can dry out if not watered soon after potting. If a small number of bags are involved, split open a bag on a potting bench and mix in enough water to moisten. If a potting machine is used, moisten and stir the mix as it is dumped into the hopper. If filled pots will not wet, the pots will have to be irrigated with a solution of wetting agent such as Aqua Gro 2000. Follow the directions on the wetting agent label. Several applications may be needed if the mix is extremely dry.

I have weeds everywhere. Where did they come from?
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Weed infestations can develop quickly because common greenhouse weeds like oxalis and bittercress grow quickly and produce hundreds of seeds that spread many feet away from the parent plant. The source of the weed seeds can be hard to pin down. A few weeds allowed to go to seed can result in a major infestation. Seeds can blow in through the vents or come in with liners. Growers who water with pond water can have weed problems because of weed seeds blowing into the pond. Occasionally, a few weed seeds may come in with the growing mix. However, major infestations are rare because mix manufacturers do their best to produce as weed free of a product as possible.

Why are my plants yellow?
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Yellow plants can result from several circumstances:

High growing-mix pH caused by alkaline irrigation water
Root systems infected with disease organisms like pythium or phytopphthora and Ital pythium phytophthora
Root damage caused by over-watering or over-fertilization
Iron deficiency induced by cool temperatures
General lack of fertility

A soil analysis can be used to diagnose causes of Nos. 1 and 5. If inspections find dead or damaged roots, cause No. 2 or 3 may be suspected. If cause No. 5 is suspected, be sure day and night temperatures are within the normal range for the crop.

The leaves on my plants are twisted and abnormal. What is the problem and how can it be corrected?
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This type of deformity is usually caused by damage to the growing points or tiny newly expanding leaves. As the leaves grow and develop, the damage becomes evident. The most common causes are from insect or pesticide damage. Once the cause has been eliminated, normal growth will resume above the damaged leaves. Exposure to ethylene gas causes leaf deformity in some plants. However, normal growth will resume after elimination of the ethylene source. Virus infections or exposure to herbicides can also cause leaf deformation with little hope for resumption of normal growth.

Does Fafard have a mix for certified organic growers?
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Yes, the Fafard Organic Formulation (FOF) product line is composed of totally organic materials. Our FOF products do not contain any synthetic materials such as pesticides, chemicals, fertilizers, or water conditioners. These mixes are organic versions of our already recognized and valued soilless mix products.

I have green scum growing on the surface of the mix. When the mix dries, it turns brown and then water will not penetrate. What causes this?
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The growth of algae results in green scum on the soil surface. When dry, the scum sets up into an impermeable barrier that makes watering difficult. Algae, being a plant, thrive in the greenhouse environment; any consistently moist area in the greenhouse is subject to algae growth. Excessive algae growth occurs when mix conditions are too wet. Over-watering, poor air circulation, and/or compacted soil result in conditions that inhibit drying and encourage algae growth. Proper water and environmental management are needed to minimize algae problems.

Are bark mixes disease suppressive?
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Aged or composted bark contains many species of naturally occurring micro-organisms. Some of these micro-organisms are relatives of the bacteria and fungi used in commercially available bio-control products. When used in a mix, properly processed bark is suppressive to some diseases for a short time. These suppressive properties should not be solely relied upon for disease control. Material that is processed properly, including bark, becomes populated with micro-organisms that suppress certain fungus diseases. It is important to note that the word "suppressive" is not the same as "prevention." Disease problems can occur in suppressive mixes under conditions of poor sanitation or heavy disease pressure. Suppressive mixes should be used as a disease-control tool along with customary fungicide and sanitation programs.

Isn’t there a shortage of peat lands in Canada? Isn’t peat harvesting depleting the wetlands?
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The North American peat industry takes environmental concerns very seriously. For example, when a peat bog is at the end of its productive life, it is mandatory that the area be restored to a functioning wetland. These restored areas can become ecologically balanced systems within five to 20 years. There is a misconception that peat is in short supply and that the harvest rate is not sustainable. Peat is a renewable resource that is accumulating 70 times faster than it is being harvested. North America has 270-million acres of peat land with only 40,000 acres (0.16%) used for peat production. There are also millions of acres in national parks and other preserves that can never be touched.

What is the CSPMA Preservation and Reclamation Policy?
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Canadian Sphagnum Peat Moss Association (CSPMA) members agree to abide by the reclamation policy for all new bog development. It includes:

Identifying bogs for preservation.
Leaving buffer zones of original vegetation to encourage natural succession after harvesting.
Leaving a layer of peat below harvesting levels to encourage rapid regrowth.
Returning harvested bogs to a functioning peatland, or if that's not possible, to other wildlife habitats or agricultural production.

For more information, please go to the CSPMA Preservation and Reclamation Policy (http://www.peatmoss.com/pm-prrec.php).

Is peat moss a renewable resource?
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Peat is considered to be a slowly renewable resource and is harvested in a sustainable manner in Canada, according to the CSPMA (http://www.peatmoss.com/index.php). Fafard is an active member in good standing with the CSPMA.

Where can I find more information on the environmental concerns with peat moss?
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The Canadian Sphagnum Peat Moss Association web site http://www.peatmoss.com/concern.phphas many resources on peat harvesting and the environment.

Watch video clips here: http://www.peatmoss.com/pm-peatvid.php

Does a potting mix have a shelf life?
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It is always preferable to use growing mix that is as fresh as possible because certain chemical and physical properties can change during storage. The degree of change depends on both storage time and conditions. Whether bagged, baled or bulk, after storage, mix can dry out becoming dusty and difficult to wet. Mix stored outdoors in humid, rainy conditions can absorb moisture and become wet and moldy. During handling and potting, wet mix is easily compacted, resulting in decreased aeration porosity. While unsightly, the mold is not pathogenic and quickly goes away on its own. Most mixes contain a starter fertilizer. As mixes age during storage, naturally occurring micro-organisms can consume some of this fertilizer, reducing the electrical conductivity and nitrogen content. If this older mix is used side-by-side with fresh, new mix, some initial growth differences might be seen, especially if the first fertilizer application is delayed. Sunlight can degrade and eventually disintegrate the plastic bags or bales used as packaging, allowing for contamination by weed seeds or disease organisms. Although there are a lot of “what ifs,” potting mixes are best used within 6 months of manufacture.

Is there an advantage to using some coir in the mix?
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Coir, derived from coconut husks, is somewhat peat-like in physical nature but there are differences. Because coir is denser than peat, during watering-in mixes with a high percentage of coir are less prone to settling down from the top of the pot than peat mixes. Coir is naturally higher in pH than peat. Compared to peat, coir contains higher potassium and sodium, resulting in higher soluble salt levels. There is also some evidence that mixes containing coir are less subject to fungus gnat infestations.

How long can I store a mix that contains a controlled-release fertilizer (CRF)?
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A good practice to follow with a mix containing CRF: use as soon as possible. With common greenhouse-use formulations, each CRF has a longevity factor, or release rate, listed on the label (e.g. 3 to 4 month, 180 day, etc.). The release rate is dependent on soil temperature in moist mix- the higher the temperature, the quicker the release rate. Because potting mixes contain some moisture, the CRF release process begins soon after the mix is made, resulting in increasing soluble salt levels. During storage release rate is affected by temperature, time, the mix’s degree of moisture and the fertilizer’s longevity factor. While any CRF-containing mix can be safely stored for a week or two before use, soluble salt levels should be checked before use after longer storage periods. If necessary, the salt level can be reduced by leaching after potting. The best management practice would be to order only that amount of mix that could be used before leaching becomes necessary. Packaged mix should be stored cool and dry to minimize high temperatures and moisture absorption.

Why is the mix pH so low when tested fresh from the bag?
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Potting mix ingredients pine bark and peat are naturally low in pH, in the 3.5 to 4.5 range. To adjust the pH up to the desired 5.5 to 6.5 range for crop production, limestone must be added. Once the mix is potted and moistened the limestone will start to react and raise mix pH. Limestone does not react instantly. It takes a period of 3 to 5 days for the reaction and the subsequent pH increase to occur. Freshly manufactured mix, straight from the bag, can be low in pH, but only until the limestone is activated upon watering in. As the mix ages during storage a slow pH increase can occur.