Question about Fertilizer...

[lambo1972]

I started using fertilizer a year or so ago per the advice of an experienced member on this site. It's working well. I use a balanced 20-20-20 fertilizer twice a month at half the strength recommended. I read that orchids are not heavy feeders and have been told the same, and I also read to use UREA free fertilizer. Many of the fertilizers sold have what is called Urea Nitrogen as the main ingredient for nitrogen. It has also been recommended to me to use a fertilizer that contains calcium and magnesium in it for an ailing zygo.

My questions are, Is the "urea nitrogen' bad? And Should I keep using the balanced fertilizer or switch to a 30-10-10? Or is the one with calcium and magnesium best? Thank you all for the advice as always!

[alecStewart1]

For calcium, I've seen a lot of people just get crushed oyster shells and sprinkle a speck on the medium before watering. You can get a big bag of it from animal/chicken feed suppliers.

Some people here use Epsom salt for magnesium, but there's also Botanicare Cal-Mag Plus. That covers calcium, magnesium and some iron, but it will be more expensive than getting Epsom salts from your local drugstore.

EDIT:

To reiterate something everyone on the board will tell you, though, fertilizers are the last thing to worry about compared to

• Light
• Watering
• Proper temperatures
• Humidity
• Airflow
• Sanitary growing conditions

Which will always be more important before anything to do with fertilizers. Fertilizers are like...PEDs (performance enhancing drugs) for plants. Your plants don't necessarily need them, but they certainly give a boost in performance.

[lambo1972]

I recently purchased a new fertilizer that actually listed calcium and magnesium as ingredients. Though they were very low concentrations...

I'm kinda between fertilizers...

[estación seca]

Egg shells and limestone chips don't release enough calcium to make any difference. You need to supply calcium in your fertilizer or your tap water.

[Roberta]

Originally Posted by lambo1972

I recently purchased a new fertilizer that actually listed calcium and magnesium as ingredients. Though they were very low concentrations...

I'm kinda between fertilizers...

What is the composition of your water? Where I live, calcium and magnesium are not an issue... hard water has lots of both. Other places have water very low in these minerals and so a formulation that adds them is needed. Likewise if you're using RO or DI water.

Absolutely correct that orchids need very little of anything. They grow slowly, and fertilizer minerals are used for growing new tissue - so slow growth, little needed. When they grow fast (Catasetinae and Cymbidiums in spring and early summer) they need more. (For those I make life easy for myself, just use a healthy pinch of time-release like Nutricote as a top dressing and then treat them the same as everything else for routine fertilizing)

Orchids CAN utilize urea nitrogen.

[lambo1972]

I think the water in my area is pretty average. Out of the tap, I think it's over 7 ph but not more than 7.6. It's been a while since I tested it. Most of the info and advice I've gotten on fertilizer has been from you, so thank you. Most of my orchids have seen good root growth, and for the first time many also grew new leaves. Most have been blooming without the use of fertilizer, but not showing the grow of new leaves.

As for the ones that do not show good growth, or are new to me, and especially in the case of the ailing zygo, I'm wondering if they need a different concoction or different chemical needs, which is why I posed my question. Really, it's just all a matter of continuing education. Thank you!

Originally Posted by Roberta

What is the composition of your water? Where I live, calcium and magnesium are not an issue... hard water has lots of both. Other places have water very low in these minerals and so a formulation that adds them is needed. Likewise if you're using RO or DI water.

Absolutely correct that orchids need very little of anything. They grow slowly, and fertilizer minerals are used for growing new tissue - so slow growth, little needed. When they grow fast (Catasetinae and Cymbidiums in spring and early summer) they need more. (For those I make life easy for myself, just use a healthy pinch of time-release like Nutricote as a top dressing and then treat them the same as everything else for routine fertilizing)

Orchids CAN utilize urea nitrogen.

[Dimples]

I’d suspect another of the needed conditions for growth would be to blame for the ailing plants, not the fertilizer. The frequency of significant nutrient imbalances when you’re using a complete formula, or a nearly complete formula with occasional tap water for the Ca/Mg, is going to be very low.

If you don’t flush occasionally and delay repotting too long, then you could start to see issues as nutrients buildup in the pot and throw things off balance, but that’s avoidable. Same for equal value fertilizers like your 20-20-20. They start out imbalanced from the plant’s perspective from the start. They’re fine if you use them lightly, so your method is good. I prefer a true all-purpose/all-plant formula in a 3-1-2 ratio but I also grow tropicals and outdoor plants.