HOW YOUR WATER CAN AFFECT YOUR ORCHID – “PHood”
VAOS Growers Clinic
Generally orchids require less fertilizer than most other plants. It is far more harmful to give an orchid too much orchid fertilizer than too little. Orchids go on living happily without any added nutrients. But feeding them the right amount of orchid fertilizer at the right time can lead to more brilliant flowers and stronger growth.
Hence the expression – Fertilize “Weakly Weekly”
When you select a fertilizer for your orchids the primary goal is to supply a sufficient amount of plant nutrients for good growth. The PROBLEM is that there are as many misconceptions as there are fertilizers labeled as orchid special fertilizer.
Water Source ___________________
PH ____________________________
TDS_________________________
Fert _________________________
The Best fertilizer to use on your orchids is the one that not only supplies nutrients, but also complements the pH and nutrient content of your water.
The pH of a solution can range between 0 (very acidic) and 14 (very alkali).
At a pH of 7.0, the solution is said to be neutral.
Michigan State University shows that most nutrients are available at their optimal level between PH levels of 5.0 to 6.0.
Most online orchid sources recommend a pH between 5.5 and 6.5 for orchids and that’s what we aim for after adding nutrients and/or other additives.
Irrigation waters should fall in the range of 5 to 6.5.
pH and its Importance
Alkalinity is a critical item to measure because it has a great effect on growing media pH. A certain amount of alkalinity is good, because it will buffer the solution from acidic influences such as peat moss and fertilizer.
The most critical aspect of your water quality is the alkalinity, because this will largely determine the conditions that will prevail around the roots of your orchids. If you notice a lot of white leaf spotting on your orchid leaves, it is likely that your water supply is highly alkaline.
Root Zone pH
The pH of the substrate or potting medium rather than the pH of the irrigation water determines the availability of nutrients to your plant. Micronutrients tend to be available at their optimum level at a slightly acidic pH.
The pH of the potting mix inside your pot is important because if it is too low you can have micronutrient toxicity. “TOO MUCH NUTRIENTS”
The primary problem with low alkalinity water is a tendency for medium-pH to drop over time, which can cause micronutrient toxicity problems.
Low pH problems are usually a result of fertilizer selection.
Micronutrient toxicity syndrome is the accumulation over time of excessive levels of trace elements in the tissues of the plant. By the time it becomes visible, the damage may be irreversible.
Symptoms of micronutrient toxicity include: slow, stunted growth; light green to yellowish green leaves; dark, brittle older leaves; fewer blooms that may not open or may be small and off color.
It depends on when the toxic effects began in the growth cycle of the plant. Leaf deformity usually occurs in older, lower leaves, but recently matured leaves will twist and curl, and eventually the new center leaves will be twisted and deformed.
The common problems associated with high alkalinity result from its tendency to increase medium-Ph. High medium-PH can cause micronutrient deficiency in container grown plants because micronutrient solubility will decrease as the medium-pH increases.
You can adjust pH with acidic materials from the kitchen. Other growers have used vinegar or grapefruit juice as the acid. (Orchid Board)
Vinegar (acid) can work to lower the pH and baking soda (alkali) can be too used to raise the pH.
Here is what they would do. Measure the pH of the water before adding acid. Use an eye dropper, add a few drops of your acid to a gallon of water, and mix thoroughly, measure again. Keep doing this; write down each step the number of drops added and the pH. You just need to be in that range from pH 5.5 – 6.5. After ; you will know the amount of acid to add to get it close to the right pH for the next time. Use your meter for a final ph check.
Water Hardness
Water hardness is important because it is closely related to pH and, just like pH, plants have certain levels of water hardness that they thrive in and if the hardness is too far off it can cause stress and death. Water hardness can be most simply described as the level of mineral in the water. Hard water has a lot of dissolved mineral and soft water has little dissolved mineral in the water
The other reason that hardness is important is that it affects pH. Hard water (high mineral content) is usually high in pH. Soft water (low mineral) is usually low in pH. The mineral in hard water will act as a buffer which will reduce the amount of acid in the water. The resulting water will be more alkaline and higher in pH.
Total Dissolved Solids
Total dissolved solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid. If your tap water is low in dissolved solids, it will be fine for use as irrigation water.
Adding fertilizer to water will drastically increase its amount of TDS; therefore, less fertilizer is required in water that already has high quantities of minerals in it. Flushing with water is very important when high TDS water is used in regular watering.
TDS SHOULD BE NO MORE THAN 500-600 w/fertilizer
The most common mineral in water is calcium; however, other minerals can also be present. Most people’s tap water is either slightly hard or soft depending on where it comes from. Well water from areas that have a lot of limestone (calcium) is often hard. Water that comes from lakes (rainwater) is often missing minerals and is soft.
Categorize Your Water Quality:
Water Type Relative Amount of Alkalinity ApproximateTDS
1 RO/Rain Very Low < 60 PPM
2 TAP Moderately Low 60 – 150 PPM
3 WELL-1 Moderately High 150 – 200 PPM
4 WELL -2 Very High 200 – 240+ PPM
To categorize your water quality, it is best to obtain an analysis.
You can get a very rough estimate of your water quality by taking a sample to a pool supply store.
Another alternative is sending your water sample off to J.R. Peters (http://everris.us.com/). At a cost of about $35 you can obtain a water analysis and then ask them to recommend a suitable fertilizer based on your actual water testing results.
Your water quality can vary greatly depending on its source.
Rainwater and Distilled Water – are sources of very pure water having a very low alkalinity, categorized as Type 1. These pure waters have virtually no buffering capacity so the addition of fertilizer can cause drops in pH and the water can end up with the acidity of vinegar. If you are using this type of pure water, you will need to use a fertilizer with calcium, magnesium and micronutrients because they are generally absent.
Public Water Supplies – are sources of reasonably good quality water having a moderately low alkalinity, categorized as Type 2, though the total dissolved solids are higher as are the pH and sodium levels, which can be over the 60 PPM.
Well Water – is high in alkalinity and total dissolved solids, categorized as Type 3 or 4. The naturally occurring calcium and magnesium may not be easily available to your orchids because the water is too alkaline.
Do not use salt softened water your orchids.
Fertilizer Type’s For Water Types:
Type 1 – Option 1
Peters Excel 13-2-13
Plug & Bedding Plant Special
Option 2
Peters Professional 17-3-17
Peat Lite Neutral Cal-Mag
Type 2 – Option 1
Peters Excel 15-5-15
Cal-Mag Special
Option 2
Peters Professional 17-3-17
Peat Lite Neutral Cal-Mag
Type 3 – Option 1
Peters Professional 15-5-25
Peat Lite Flowering Crop Special
Option 2
Peters Professional 18-8-17
Peat Lite High Mag Special
Type 4 – Option 1
Peters Professional 15-5-25
Peat Lite Flowering Crop Special
Option 2
Peters Professional 18-8-17
Peat Lite High Mag Special
Below is the concentration (in PPM) obtained when mixing ¼, ½, 1, or 3 teaspoons into a gallon of water with different fertilizers: Amount of fertilizer added Per gallon of solution giving approximate PPM of TDS
¼ teaspoon ½ tsp. 1 tsp. 3 tsp.
30-10-30 120 240 475 1425
21-7-7 85 165 225 1000
21-5-20 85 165 225 1000
20-20-20 80 160 320 950
20-10-20 80 160 320 950
19-4-23-2 Ca 75 150 300 900
17-5-17-3 Ca-1 Mg 70 135 270 810
15-5-15-5 Ca-2 Mg 60 120 240 710
15-3-20-3 Ca-1 Mg 60 120 240 710
14-4-14-5 Ca-2 Mg 55 110 220 660
13-2-13-6 Ca-3 Mg 50 105 210 620
13-3-15-8 Ca-2 Mg 50 105 210 620
10-30-20 40 80 160 475
9-45-15 35 70 145 425
6-30-30 25 50 95 285
This chart shows that if you have harder water (more TDS) you will get better results with a weaker solution of fertilizers.
SUMMARY
In general, irrigation waters should fall in the pH range of 5 to 6.5 with fertilizer added.
Fertilizer is typically acidic. When added to pure water, standard fertilizers can quickly drop the pH to below 6.
In addition to fertilizer orchids need Calcium and Magnesium …. Is it in your water?
Calcium is an essential element for plant growth that is often present in Irrigation water. It is required in large quantities by young growing tissues, strengthening stems and promoting strong overall plant growth.
—— Low levels will lead to poorly developed younger leaves and buds.
Magnesium is an essential element for plant growth that is often present in Irrigation water.
——– It is an important component of chlorophyll, the green pigment that is responsible for photosynthesis.
The pH meter is important. The importance of this instrument rests on the fact that orchids can only take up nutrients from their medium if it’s in the proper pH range.
If your growing media is already acidic (from decaying organic matter, especially containing peat or sphagnum moss), this can inhibit nutrient uptake in the roots.
(Acidic media + acidic fertilizer = No Uptake of Fertilizer)
If you’re using tap water, however, this may not be a problem.
In many parts of the country, especially those using well water, mineral content is already high enough that the water pH is alkaline.
If this is the case, the mix of the fertilizer and the naturally occurring minerals may react to balance the pH to an optimal level, between 5 and 6.5.
(Acidic media +acid fertilizer +alkaline water = may balance)
The only way to know is to test it.
Presented by Jay Loeffler and Rich Amos