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Potting Soil & Nutrients

Posted by saood none (My Page) on
Fri, Sep 27, 13 at 1:18

Before I start off with my question, I wish to give some introductory information

I am a new gardener (starting with container gardener on the roof as I don't have any garden space) living in the hot climate of Saudi Arabia in Al Khobar (these days the highest temperature over here exceeds a bit above 100F - Ranges from 75-103 and expected to remain that way until mid of October). The lowest temperature will be 50F in January.

Not much options for me with the potting soil over here. When I read discussion or articles about container gardening I hear a lot about Miracle grow and Liquid fertilizers and potting soil being fertilized or not. Bone meal, blood meal etc. etc. Frankly I am not able to understand how this works.

The people at the local nursery are also not educated enough. They just follow what they have been following for ages without much thought on NPK, Secondary and micro nutrients etc. So there isn't much local help either.

After that introduction, my question is, I have access to two brands of potting soil. One of the potting soil says that it is enriched however it can be fertilzed with a liquid fertilizer once or twice a week. It also says it is suitable for planting vegetables. The other information available on it is 95% organic matter, Ph 5-6, Ash content - less than 5%.

The other potting soil (according to German standard - as claimed) is a bit more sophisticated whose constituents are described on it as follows:

91% Organic dry matter, moisture content 70%
PH 6-7
N,P,K - each more than 0.21%
and then a list of secondary and micro nutrients described as PPM.

I am growing vegetables - starting with tomatoes, pepper and cucumber and as the weather gets a bit cooler, with peas, carrots, potatoes - all in containers.

My question is how to transplant the small plants that I buy from the nursery into the pot? Should I just transplant it in the potting soil without any fertlizer or should I add fertlizer also at the time of preparing the container for the first time? How often do I need to fertlize? When does fertlization start? Or is fertlization not required or required very late when the fruits set it?

The local nursery guys tell me to transplant the plants in the first one and put fertlizer after 1 month - once a month - by just sprinkling on the sides of the plant.

Btw the way fertilizer options are also quite limited here and we have either 100% composted cow manure or NPK pellets, The nursery guy is recommending using cow manure.

Also can you help me better understand how much NPK and other secondary and micro nutrients are required in a container of lets say 1 gallon? As a percentage of the total soil? or some other way to understand. This German standard potting soil says 0.21% each of NPK. Does that mean that NPK required only about 0.63% - which would make around - well it would make are 0.25 litres approx for each gallon of soil. Is this what is required in reality? It feels so less.

It would be a great help from the GW community to help me out in this area. I will certainly appreciate it.

Regards

Saood


Follow-Up Postings:

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RE: Potting Soil & Nutrients

Hello SAood;

What kind of plant are you raising?

Most plants favor a common environment (soil quality, basic nutrients) some don't. The most important factors are 1) Air, 2) Moisture and 3) nutrients. In that order. Without aeration and moisture regulation, the plant cannot utilize nutrients. it's a very delicate environment on a microbial level.

For me, successful gardening began when I studied the needs of the plant. Then, the needs of the soil to feed the plant. In short, feed the soil and feed the plant. Then, the plant feeds you. But all plants are different. While many plants favor similarities for soil quality, the nutritional needs of each plant can vary and sometimes that variance is large. For example, roses prefer a more acidic soil than common vegetables. I'm generalizing with this.

It's helpful to discover the origins of the plant, if possible, and imagine it's native growing environment. For example, I'm growing garbanzo beans (chick peas) next year because my children love hummus tahini. Garbanzo beans, native to the middle east are familiar to arid lands depleted of nitrogen. Adding nitrogen to a garbanzo bean plant creates green foliage and few or no beans. It needs to be forced to struggle in the soil or it won't produce beans. This is why garbanzo beans is one of the larges "legume" plants used world wide. It doesn't require much nitrogen and does well in poor soils.

For other plants, the time of growth of the individual plant is what's important. Some potted plants require extra fertilizer during the flowering stage, like tomatoes (if I remember correctly). Other plants will die if fertilized during the flowering stage. And others prefer less fertilizer, like the garbanzo bean plant.

Most of my garden soil needs nitrogen of some sort. (I grow organically so I use home made compost and worm compost.) I had to study the needs of the garbanzo bean plant to find out adding nitrogen isn't a good thing.

So, when making your own potting soil the advantage is having the ability to create the soil that individual plant can use best.

There is a general starting point of basic nutrients for standard potting soil. I'm hoping someone will chime in. I don't know these numbers because I garden organically without the use of chemical fertilizers. I rely upon home made compost from kitchen and garden waste and also worm compost (from worms). When using these, it isn't necessary bother much with the nutrients unless the plant is very unique with its needs, like garbanzo beans. Unlike chemical fertilizers, home made fertilizers will not harm plants when placed at the wrong time or when using too much because the plant can more readily absorb the natural version and too much of it will not burn the roots and stems.

Adding to the confusion are certain types of plants engineered to behave different than the original plant of its species in order to survive certain conditions like bug infestations, extreme drought or poor soils.

Be certain to check with your local university agricultural departments. Much of their work is world-renowned. Middle eastern varieties of vegetable seeds have reached the dry soils of my garden because they are well adapted to drought.

Good luck!


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RE: Potting Soil & Nutrients

Thanks ChickenCoupe for your reply.

I am raising tomatoes, pepper and cucumber now and after a month or so when the temperature gets a bit further down, will go for carrots, potatoes, coriander, peas etc. Even strawberries.

Waiting for a more specific reply on the above vegetables/fruits.


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RE: Potting Soil & Nutrients

  • Posted by TXEB 9a (My Page) on
    Fri, Sep 27, 13 at 13:26

saood - you may better served posting this in the Vegetable Gardening Forum, the Container Gardening Forum and the Tomato Forum. Also check out this from the Vegetable Forum FAQ page.

This post was edited by TXEB on Fri, Sep 27, 13 at 13:30


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RE: Potting Soil & Nutrients

One question: how big are the pots you are using? I hope they are very large because with the temperatures you experience, the plants will dry out very quickly. If the pots are very large, perhaps you could bury some kitchen scraps in the pot to provide organic nutrients to help things grow.


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RE: Potting Soil & Nutrients

Hi Dottyinduncan

Right now the pots are 14" diameter and 12" depth. The plants are small (just 6 inches tall), so I dont think they are drying up. Also since this is my first time with gardening I am a bit extra conscious not to let them dry (also ensuring though not to overwater them). I have taken the time to read good books on vegetable and container gardening - both for dummies series. However, since I donot have quite a lot of option for soil and fertlizer and further the technical expertise is also missing on ground, so I am referring to this forum for help.

Btw, should I put some kitchen waste - uncomposted - before puting any soil into the pot? And how much, if at all. Someone told me that even if I go extra on the kitchen waste, it wont be harmful for the plant. Is that so?

Btw, since I have raised the matter of soil in this post, may I ask one related question. As the books and the general internet research tells me to water untill we see water flowing from the drainage holes. I do the same way. However, I realized that by doing this the excess water that gets into the pot waits there untill it drains out. This might be taking an hour or two - may be three it the pot is big. Is it ok for the plants to sit for that time under heavy watered soil.


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RE: Potting Soil & Nutrients

No - do not put any scraps or kitchen waste into the containers before filling. The reason for this is that there is simply not enough bacterial and fungal life in potting soil to be able to properly break down and decompose this stuff. That is one of the issues with adding raw organic matter or even granular organic fertilizers to container plantings - the soil biology is not present in any populations sufficient to assimilate and process these materials.

Without more specific information as to the composition of your potting soil(s) and specifically what nutrients they may possess, it's a bit difficult to suggest what additional fertilizing they may require. Because of the need to water containerized plantings so frequently - and even more so in your climate - you will need to fertilize frequently. If you can manage, a liquid or water soluble fertilizer would be my first choice unless you have some sort of slow release product (like Osmocote) available. And then the suggestion would be to water "weekly, weakly" - or every 7 days during the growing season at half strength.

If no liquid/water soluble fertilizer or slow release product available, I'd make a compost tea out of the manure and use that.

As to your watering practices, I think you are on the right track. Just don't let the pots sit in water, like some sort of saucer. It also helps if the pots are raised above grade so that the drainage hole is not obstructed. As long as the potting soil itself is freely draining and the container has a sufficiently large drainage hole you should be fine.

FWIW, container growing is very different from growing plants in the ground, including the medium and how and when to water or fertilize, so that info tailored specifically to that task is most beneficial. With that in mind, I'd suggest you visit the Container Gardening forum for lots of excellent advice. I'm linking to one thread that is perhaps the most informative to someone new to this activity.

Here is a link that might be useful: potting soils and water movement


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RE: Potting Soil & Nutrients

  • Posted by saood Saudi Arabia (My Page) on
    Sun, Sep 29, 13 at 8:15

Thank Gardengal

This is the soil composition, if that might help you for answering my question

91% Organic dry matter, moisture content 70%
PH 6-7
N,P,K - each more than 0.21%
and then a list of secondary and micro nutrients described as PPM.

Do I need any further fertilization - both at the first transplanting stage and later as the vegetables plant grow in their containers?


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RE: Potting Soil & Nutrients

Saood, what IS the "organic dry matter "? Is it peat moss, coir, bark fines? Those are examples of the typical types of organic matter that comprises potting mixes.

And what is the rest of the solid portion? Perhaps perlite or vermiculite?


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RE: Potting Soil & Nutrients

Saood, what IS the "organic dry matter "? Is it peat moss, coir, bark fines? Those are examples of the typical types of organic matter that comprises potting mixes.

And what is the rest of the solid portion? Perhaps perlite or vermiculite?


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RE: Potting Soil & Nutrients

  • Posted by saood Saudi Arabia (My Page) on
    Sun, Sep 29, 13 at 9:52

Hi Rhizo: While it doesn't say what is organic dry matter, but yes most probably it is peat moss and others that you have listed. The remaining is most likely perlite/vermiculite.


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RE: Potting Soil & Nutrients

Well, that sounds very much like an ordinary potting mix....we call them "soil-less " mixes because they do not contain real soil. The medium should be quite coarse textured, chunky rather than powdery.

You will need to provide fertilizer of some sort. I prefer to use a soluble liquid for my container grown plants.....what kinds of products does the local nursery carry?

Gardengal is giving you excellent advice for your situation.


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RE: Potting Soil & Nutrients

  • Posted by saood Saudi Arabia (My Page) on
    Sun, Sep 29, 13 at 11:31

Yes, I have no doubt that it is very much like the normal soilless mixes but I was just comparing the NPK %ages of the my locally available mix with that of Miracle gro of the US. Miracle Gro has 0.21% - 0.07% and 0.14% of NPK and with those %ages it claims that fertilization is not required for upto six months (so I can assume that 3 months can be easily done without fertilizer). The locally available mix that I have available however includes 0.21%:0.21%:0.21% for all NPK. So with these numbers - can I assume that I don't need to fertilize for at least the beginning month(s)? The nursery guy says that I need to sprinkle fertilizer once a month.

Am I thinking on the right lines?


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RE: Potting Soil & Nutrients

  • Posted by socalgal USDA z10 Sunset z24, (My Page) on
    Sun, Sep 29, 13 at 14:09

Because your locally available mix has those NPK percentages, you do not need to fertilize right away. However, because you need to water so frequently with your high temperatures and relatively small pots, that fertilizer is not going to last for six months. If your plants grow very well at first and then slow down (and it is not due to cooler weather or becoming potbound) or become pale green, that could be a sign that fertilizer is needed.


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RE: Potting Soil & Nutrients

Thanks socalgal

But how much to fertilize later. Frankly, I dont know how much is too much or too less. Also how should I apply the fertilizer? Just a sprinkle or a spoon full or two inside the top layer of the soil or any other way?

Btw, my tomato and pepper plants which I bought a couple of weeks back from the local garden shop have not shown any significant growth in their new bigger pots. Is it a sign of fertlization need.


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RE: Potting Soil & Nutrients

  • Posted by socalgal USDA z10 Sunset z24, (My Page) on
    Mon, Sep 30, 13 at 13:03

It is so hard to tell what is happening to your tomato plants from halfway around the world! Have they grown at all? Perhaps the leaves have gotten larger even if the plants aren't much taller? What did the roots look like when you transplanted them? Were the roots crowded, and if so did you separate them at all? Are the leaves dark or light green or ...? Has the color changed since you purchased them? How hot has it been - sometimes growth slows down when it gets too hot.

Which type of fertilizer have you purchased, and what is the NPK? That will help determine how much to use. Too much OR too little fertilizer can harm plants.


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