Fertillzer

[Nicolasdperez]

I was recently looking at my fertilizer analysis and realized that it does not have any calcium. I was wondering if I would need to add calcium to my orchids. I think my tap water may have small levels of calcium, however I am unsure if it is enough to support an orchid. If I need to add calcium, would egg shells be the way to go? Thank you for your time

[Roberta]

Your water supplier should publish an analysis annually, probably on their website. It may or may not be helpful... sometimes they just focus on verifying that pollutants are below Federal levels. But some do list other constituents - like calcium. I doubt that egshells will help much - they are quite insoluble. There are Cal-Mag supplements that can be used, but you first want to verify that they're needed. Where are you located?

[Nicolasdperez]

Thank you. I will look into my water supplier's analysis. I have used eggs for my outdoor garden by crushing them up and dissolving them in lemon juice to make it water soluble; however I believe that this would also require me to adjust the ph. I am located in California.

[estación seca]

A lot of California has plenty of calcium in the water, but the pH is often high (8.0-8.5), which slows calcium absorption by plants. Go to your water utility's Web page and search for "water quality report." Sometimes calcium is shown explicitly. Sometimes a number is published for total dissolved solids (TDS) in parts per million. Much of that will be calcium.

[Roberta]

Originally Posted by Nicolasdperez

Thank you. I will look into my water supplier's analysis. I have used eggs for my outdoor garden by crushing them up and dissolving them in lemon juice to make it water soluble; however I believe that this would also require me to adjust the ph. I am located in California.

Depending on which part of California (it's a really big place), many places (certainly true in southern California) have plenty of calcium in the water. San Francisco water is superb just as it is (maybe can use a bit of cal-mag supplement). But in some of the surrounding communities if the water is very pure, water companies add sodium hydroxide to adjust pH. (take really good water and turn it into not-so-good water) So this is something that you need to pursue on a local level...

[Nicolasdperez]

My calcium levels are very high, however my house has a water softener installed which reduces mineral content. There is one hose outside, however, that does not have a water softener on it. How often should I water all of my plants with this hard water? I have pH kits for hydroponics; Should I make sure that the pH of this water is between 5.5-6.5 when watering my orchids?

[Roberta]

Definitely don't use softened water on plants... a water softener doesn't actually remove minerals, it replaces the calcium, usually with sodium,so you don't get soap scum but it is toxic to plants. If you use the outside water and adjust the pH down, most orchids will be fine - that's the optimal pH range for absorbing nutrients from fertilizer - and the calcium will be available to the plants. When you're not fertilizing, you probably don't even have to go that far. There are a few groups that are sensitive to high mineral content (like Pleurothallids and other cloud-forest species) but most of the orchids that people grow - Phalaenopsis, Cattleya group, Oncidiums, Cymbidiums, etc., are fine with rather bad city water.

[Nicolasdperez]

Thank you for all your help. Have a good day.

[Shadeflower]

I've compared those numbers to mine and the composition is way off.
It has got some Iron, zinc and copper but not in the right quantity, then it is missing:

Calcium, Magnesium, Sulphate, Boron, Molybdenum and Cobalt

To rectify this would be like trying to convert diesel fuel to petrol. You might as well just toss it and buy the right stuff.

The thing you are missing won't be calcium. It's the ratio of all the nutrients that are important.

Just like baking a cake, if you leave out the sugar, it won't be very sweet, if you add too much salt it will be too salty so you have to get the recipe right.

You can't go leaving out ingredients like Calcium, Magnesium, Sulphate, Boron, Molybdenum and Cobalt and then throw in some egg shells. It's not enough and you won't know how much to add.

I luckily don't worry about the right ratio - I just bought a fertilizer that has all that done already but I do know it's all about the right ratio. 20-20-20 can be ok and in soil micronutrients are only needed in small doses but orchids are not grown in soil so rely on all micronutients from the fertilizer.

Fertilizier is not expensive at all. The cheap brands cost more comparatively considering how much they are lacking vs a complete fertilizer with all micronutrients and calcium and magnesium in the right quantity.

Some might argue that orchids need so little fertilizer that it doesn't matter but I would argue then that bugs eat so little because they are so small that they can survive without food but just because they eat little does not mean they can survive completely without.

[Roberta]

I would have no problem using that 20-20-20 fertilizer. Of all of the cultural factors for successful orchid growing, fertilizer is at the bottom of the list. Get light, temperature, watering, and media right first. A long time (and very successful) orchid grower in one of my societies was asked what kind of fertilizer he used, and his response was "whatever is on sale at K-Mart or Home Depot". Orchids grow really slowly... fertilizer minerals give the plant what it needs to build cell walls, chloroplasts, etc. Most orchids give you maybe one growth per year, maybe two... so they're not adding new tissue very fast. Think of fertilizer as "vitamins" not "food" - green plants make their own food (carbs) by photosynthesis.

That being said, there are exceptions to every rule... Catasetums and relatives, which go dormant in winter (and want neither fertilizer nor even water when they do) grow very rapidly in the spring and summer - and so need more fertilizer than other orchids during that time. But then, that's just the flip side of the "slow growth little fertilizer"... if it's growing like a tomato, feed it like one. If not, scale fertilizer use accordingly.

Evidence of how well orchids can grow getting city water, pH 7.8-8.0, (every 2 or 3 days in summer, every 3 or 4 days in winter) and very occasional fertilizer (about 1/2 teaspoon per gallon every 2 or 3 weeks, pH adjusted)... this is a bit of what is blooming in my yard right now. Is it optimum? No. Is it adequate? Apparently...