Good nutrient sources for phals

[Cattleya234]

I’ve had some phals for over a year now and never fertilized. I’ll buy fertilizer if I have to, but if there’s any cheaper alternatives that you know of, that would be extremely helpful. I’ve read Epsom salt, but I don’t want to unnecessarily add excess salt to the pot. Thanks for any help!

[estación seca]

It depends on what your potting media is, and what is in your water.

Nitrogen is the limiting nutrient for most plants. Bark or other typical media have very few nutrients of any kind, especially nitrogen. Fertilizing is concerned mainly with supplying nitrogen. This is difficult without using a commercial fertilizer.

Many people's tap water has plenty of minerals, but many municipalities adjust the tap water pH close to 8 or lower, which makes it difficult for plants to take up many of those minerals. If growers measure tap water pH and adjust with some form of acid to around 6-7, the minerals in the tap water may be sufficient for most orchids. But nitrogen is still the issue.

Fertilizer is very inexpensive compared to orchids. However, a lot of fertilizers sold for orchids are quite expensive compared to other fertilizers. Most people will be able to grow orchids just fine using the least expensive 20-20-20 formula they can buy. Use a nitrogen calculator to calculate how much you want to add to get the nitrogen content you desire.

If you have a house, and fertilize your landscape, it is far cheaper to buy 20-20-20 with micronutrients fertilizer in large bags from an agricultural supply company. I am sure they exist in Minnesota, because there is so much agriculture. You can use that fertilizer on your plants, too.

[camille1585]

Do you have any fertilizer laying around that you use on other types of plants? Depending on what it is, you may be able to use it for orchids, but simply at a much lower concentration.

[Cattleya234]

I have some African violet fertilizer lying around, but that isn’t 20-20-20, it’s more like 8-14-9. I don’t know that it would work.

[estación seca]

Yes, you can dilute it as you wish. There is an extensive discussion of fertilizer for orchids on the firstrays.com Web site. There is also a nitrogen calculator where you input the N number from the fertilizer package, and it gives you the amount to use for a given volume of water to get desired quantities of nitrogen in parts per million (ppm.)

How much fertilizer to use depends on how often you want to fertilize, and what stage of growth the plant is in. If your Phal won't be growing much over the winter because temperatures will be cooler, you won't need to fertilize very often. But if your house is warmer and it will be growing people often use 10-25 ppm nitrogen if they fertilize every watering, and 125-150 ppm nitrogen if they fertilize every 1-2 weeks.

[Cattleya234]

It’ll definitely be cooler in my house for winter, however this phal started putting out a whole flush of new growth in late September, and won’t be done until well into December (two new leaves coming in at the same time!). Does this mean that I should still fertilize, or should I let it finish growing with no nutrients?

[estación seca]

You could do it either way. It might stop, then start up again when it warms up.

Many people in northern climates with cool to cold houses in the winter use small heat mats for Phals. It can make a big difference in how well they overwinter. Phals are warm growing plants that don't like to be cool.

Look up posts from greenpassion. She lives in Vermont, and grows really nice Phals.

[Ray]

ES is right that nitrogen is the key nutrient, and that it is generally unavailable without fertilizer application.

How much you feed is tied to how often, as he stated, with less concentrated/more often being better than more concentrated/less often. I think two weeks is about as infrequent as I’d recommend, and using the 100 ppm N level as the target, you can estimate the amount to mix any fertilizer by dividing the 8 by the %N on the label, with the result being teaspoons-per-gallon. So, you could use the African violets fertilizer at 8/8= 1 teaspoon/gallon and apply it every couple of weeks.

[Fuerte Rav]

Ray, I really appreciate all the calculations and formulas you post to help us with our fertilising but I've just realised that you are probably talking US gallons, not Imperial gallons (UK). I've tied myself in knots mentally trying to work out US gallon to UK gallon or preferably the litres that I work in now. Please can you tell me what dilution I should use of a 10-10-10 in litres for the 100 ppm N? I normally mix 5 litres at a time. Quite happy to work in mls rather than teaspoons!
TIA.

[estación seca]

Go to Ray's Web site firstrays.com and look in the Fertilizer section. There is a nitrogen concentration calculator that has both US and SI units.