AboutThe Long Island Gardener Expertise Do you know the wrong fertilizer will keep your plants from blooming?
Do you know that too much Nitrogen can kill your grass, even if it does not burn the roots? Do you know that Roses need a LOT of Nitrogen to bloom -- and why is that?
There's some complex chemistry in those plant foods. The secrets behind N-P-K are the key to the ultimate lawn, the the biggest flowers, the most fruits and vegetables. And if you don't get it right, you could be sorry.
I'll show you what you did wrong, and how to fix it.
Experience Homeowner with gardens indoors and outdoors, lawns back and forth. I wrote my first gardening column for our college newspaper, teaching roomates about the right way to feed those windowsills gardens. Today I look for challenges. Organic Fertilizers are the key to proper feeding of all our plants. Can you make your own fertilizer? Some people think so -- but there are side effects. I have been there, done that for 54 years and there is nothing like the voice of experience when it comes to Horticulture and Fertilizers.
Publications Numerous and sundry but only in college did I write about plants.
Education/Credentials B.A., Botany and Mass Communications.
which NPK should we use for Kalanchoe and Rose ? I read one article told NPK 2:1:2 good for blooming Kalanchoe flowers, another article said NPK 1:3:1 is better. I'm confused now. Ditto for roses, which NPK good for blooming flowers ? Can I add CaO (from drying material like silica gel) and Mg(OH)2 (from medicine for stomachache) ? Thank's for your help.
Rgds,
Ari
ANSWER: These amendments are moot, my friend, because you do not know what you HAVE in your Soil.
You have one container of 2-1-2. Another with 1-3-1. You think you are putting it in current 0-0-0 Soil? Think again. There's microbes in that Soil Are you dealing with Soil in the garden, or Soil in a pot? Makes a big difference. Who knows if you need ANY Mg or Ca at all? There's only one way to find out.
Give me your zipcode, and I will give you all the information you need to TEST YOUR SOIL!
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QUESTION: Thank's for the reply.
I'm dealing with pot soil and actually I don't want to bother so much with testing soil.
Let's say that we have 0-0-0 pot soil, which NPK is best to bloom Calandiva flowers ? 2-1-2 or 1-3-1 ? Ditto for Roses ?
I read once that Phosphate helps to bloom flowers and Roses need lots of Nitrogen. Thank's.
Answer You're right to assume that potting Soil is a very different environment from outside real estate landscape Soil -- the kind that we submit for testing.
So let's go over the rules about fertilizing potted plants.
IF you have a plant that is growing in a big enough pot (very hard to do with Roses), IF you have a plant that is getting enough Sun (ditto), IF you have a plant that has not been over-fertilized, there MIGHT be a need for Phosphorus.
Roses however need a lot of Nitrogen because they don't build flowers out of Phosphorus. They build flowers out of energy from photosynthesis, which is completely determined by the NUMBER OF LEAVES they have. Every Rose is different, but if you spike a Rose's diet with Phosphorus, there will be at BEST no effect, and at WORST a shortage of other nutrients; the Phosphorus is something of a bully and it takes up all the space that other nutrients need when you put down too much.
Kalanchoes are succulents. They have a lot of leaves when compared to Roses, they need a LOT less light, they are simpler plants and grow very well as pot plants.
The most important rule you can follow for both of these -- both are potted plants -- is that you NOT use chemical fertilizers OR potting soil that comes with fertilizer mixed in...
because...
The chemical fertilizers build up as 'Salt' and damage the plants after a season of this. The soil is Salty, the plant is miserable, becomes susceptible to disease, you don't know what's wrong and then all h$@^ breaks loose. Stick with Bone Meal for Phosphorus, which releases very slowly (via microbes), and Fish Emulsion or other gentle Nitrogen fertilizer for your Rose.
I understand why you would want to get a simple answer about the N-P-K. Fertilizer companies like to push this idea. It's all marketing.
In the outdoor world, where soil testing IS done, Phosphorus builds up in the soil until nothing blooms. Then we test, and we find out what's wrong, and stop pushing P. Most soil is fine and dandy for growing anything you want, with no fertilizer. Organic matter is the best amendment you can give it. That goes for potting soil, too -- Compost, composted Manure, composted Humus. They are not N,P, or K, but they build strong bodies 12 ways.
Your Calandiva is a state of the art Kalanchoe. This will turn heads once it's up and running. Just don't give it too much light, and after a rash of flowers, deadhead and let it rest a month and even dry out to recover.
If you can grow a Rose in a pot long term, you should go into botany for a living. Watch out for Spider Mites and Aphids. Good luck. Any followups, I'm happy to read them.
