Fertilizer in Potting Soil – Good or Unhealthy?
Within the good outdated days, industrial potting soil (media) contained no added fertilizer. At the moment, an increasing number of merchandise comprise some fertilizer, both in artificial or natural kind. Gardeners have been led to consider they’ll fertilize much less and skip fertilizing seedlings. Some consider they’ll cease fertilizing houseplants totally. However nobody appears to debate the elephant within the room!
How a lot fertilizer has been added? Do you have to cease fertilizing? When does the added fertilizer run out? How rapidly are the vitamins accessible to crops? This weblog will reply these and different questions on this mysterious fertilizer.
Key Takeaways
- Potting soil producers don’t present sufficient details about their merchandise.
- The fertilizer in these merchandise is simply too low to develop crops.
- Repotted crops, together with seedlings, needs to be fertilized immediately.
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What Sort of Fertilizer is Added to Potting Media?
The knowledge offered by producers may be very restricted, even for those who contact their assist workplace, as I did. None gives the identify of the fertilizer added besides in very obscure phrases like “compost”, “sluggish launch”, or “artificial”.
Some corporations promote this side of their product pretty strongly and print it proper on the entrance of their product. Others like Premier, the makers of Professional-Combine, don’t even checklist it with their product. You need to dig by well-hidden specs to search out it.
I chosen some standard North American merchandise and summarized them within the following desk.
| Sort of Potting Soil | Sort of Fertilizer | Quantity of Fertilizer | Wait Time earlier than Fertilizing |
|---|---|---|---|
| Professional-Combine HP | symthetic | not specified | 7-10 days |
| Espoma Natural Potting Combine | natural | not specified | zero days |
| Miracle-Gro Potting Combine | slow-release artificial | 0.21-0.11-0.16 | 1 month or 6 months – they’re undecided! |
| Vigoro All-purpose Potting Combine | slow-release artificial | 0.07-0.04-0.03 | 9 months or sooner |
| FoxFarm Completely happy Frog Potting Soil | natural | 0.3-0.3-0.05 | not specified – they counsel feeding after planting |
With out an NPK worth, you don’t have any thought how a lot fertilizer was added to the combo.
Professional-Combine HP Rising Media
Sphagnum Peat Moss (65-75%), perlite, calcitic and dolomitic limestone, wetting agent.
I exploit the common Professional-Combine HP.
Fertilizer:
- Particulars of the fertilizer will not be accessible.
- They suggest beginning a fertilizer program inside 7-10 days after planting.
Espoma Natural Potting Combine
Comprises 60-70% processed forest merchandise, sphagnum peat moss, perlite, humus, and limestone to regulate pH.
Fertilizer:
- Earthworm castings, alfalfa meal, kelp meal, feather meal, & yucca extract.
- They don’t take into account these natural supplies as fertilizer, they usually instructed me that customers ought to begin fertilizing as quickly as crops are potted up.
- They’ll’t present details about the portions of those supplies within the product.
Miracle-Gro
They supply no clear description of the fabric used to make the product, however trace that it could comprise sphagnum peat moss and coconut coir.
Fertilizer:
- Particulars of the fertilizer will not be accessible.
- Specs say it feeds crops for six months, however their promoting suggests you need to begin a feeding program after 30 days.
Vigoro All-Function Potting Combine
Composted forest merchandise (55-65%), coir, peat, sphagnum peat moss, perlite, wetting agent.
Fertilizer:
- Sluggish-release fertilizer with NPK, 0.07-0.04-0.03.
- Feeds for 9 months in accordance with the bag, however directions say to begin feeding as quickly because the plant stops rising or develops yellow leaves.
FoxFarm Completely happy Frog Potting Soil
Aged forest merchandise (50-60%), sphagnum peat moss, and perlite.
Fertilizer:
- Natural materials: worm casts, bat guano, oyster shell, and dolomite lime.
- NPK is 0.3-0.3-0.05. 0.03% nitrogen is soluble, and 0.27% nitrogen isn’t soluble.
- The time to begin feeding isn’t specified, however they do say, “For finest outcomes, feed with their model of liquid plant meals” after planting.
How A lot Fertilizer is In The Bag?
The NPK numbers appear low in comparison with luggage of fertilizer or compost, however keep in mind that this materials is used straight out of the bag with out dilution.
How do the numbers examine to the advised fertilizer focus for potted crops, specifically 100 ppm nitrogen?
Peat moss absorbs about 20 occasions its weight of water. If we assume potting media will do the identical, 100 g of soil will produce 2,000 g of combine, or 2 liters. If it has a nitrogen degree of 0.2%, it will produce a combination of 200 mg / 2 L, or 100 ppm.
That is an approximate worth, and wooden merchandise could soak up a special quantity of water, however a nitrogen degree of 0.2% is in step with the advised nitrogen degree. Sadly, producers don’t even present the nitrogen degree in a newly potted plant, which might be extra helpful than an NPK worth.
Remember that this assumes the entire nitrogen is in a soluble, plant-available kind. Nitrogen in a slow-release kind, or nitrogen in natural materials, will NOT offer you this degree of nitrogen.
You probably have one other have a look at the above desk, there’s not a single product that gives the nitrogen degree and makes use of a soluble type of nitrogen. What does this imply? For the merchandise listed, a gardener has no thought how a lot nitrogen is obtainable to their crops at planting time.
Use this helpful Fertilizer PPM Calculator to arrange your fertilizer to the specified worth.
Soluble Artificial Fertilizer
That is your typical plant fertilizer. It comes as a stable that’s added to water in a prescribed quantity. As quickly because the crystals dissolve, the nitrogen is obtainable to crops.
As soon as in a plant pot, the nitrogen is definitely washed out as you water the plant. This type of nitrogen is a short-term feed for the plant.
Liquid Artificial Fertilizer
That is just like the soluble artificial fertilizer besides that the producer has already dissolved the crystals for you and has charged you a hefty worth for the comfort. You may nonetheless need to dilute the fabric earlier than you utilize it.
This nitrogen can be accessible instantly to crops.
Sluggish-release Artificial Fertilizer
This fertilizer is just like the above two sorts besides that the vitamins are locked away in a small particle, both a plastic bead or a sulfur-coated particle.
A small quantity of nitrogen is launched every time you water the plant.
The advantage of this fertilizer over the above two is that it lasts longer, releasing nitrogen for an prolonged time period, wherever from weeks to months. The discharge price is managed by the chemical design of the bead.
Sluggish-release Natural Fertilizer
This class contains many of the standard natural fertilizers, resembling compost, worm casts, manure, fish extract, blood meal, and so on.
Very little of the nitrogen is obtainable when the potting media is first used as a result of vitamins are tied up in giant molecules. It takes time to decompose these molecules and launch the nitrogen.
The speed at which nitrogen is launched will depend on the supply. For instance, compost releases nitrogen very slowly over a number of years. Blood meal, however, decomposes rapidly and releases its nitrogen over a few months.
When Ought to You Begin Fertilizing Crops?
Assume that you simply wish to hold the nitrogen degree at 100 ppm, as a result of that’s the degree that grows the most effective crops. It’s best to then begin fertilizing as soon as the extent drops beneath 100 ppm.
Nitrogen ranges in a pot or container change for various causes.
Sadly, potting soil producers present no details about this course of for his or her merchandise. You might have zero information in regards to the nitrogen degree per week after potting up a plant or 2 months after potting up a plant. It’s due to this fact inconceivable so that you can know when to begin fertilizing.
Most merchandise offer you a tough suggestion, resembling 2 months or per week, however then others say they comprise fertilizer, and you need to begin fertilizing immediately. Miracle-Gro provides you two values: 1 month and 6 months. Vigoro has the bottom NPK and the very best wait time of 9 months.
To be trustworthy, I don’t belief any of their suggestions as a result of none of them present a chart exhibiting the change in nitrogen over time. Such a chart will differ from person to person, however a minimum of an approximate chart is healthier than nothing. I wish to see some actual information.
I requested a number of of them for such information, they usually don’t have it. But when they don’t have it, how do they give you their advice? The one approach they know when you need to begin fertilizing is to have this information.
Vigoro advised that you simply wait till the leaves begin going yellow after which begin fertilizing. By the point you see yellow leaves, it’s well beyond the purpose the place you need to fertilize. The plant is already confused.
It’s also necessary to know that slow-release fertilizers, both artificial or natural, solely present a small a part of their vitamins on any given day. It is among the main limitations of natural fertilizer.
For instance, the Completely happy Frog product has an NPK of 0.3-0.3-0.05, however solely 0.03% nitrogen is soluble. Meaning on day one, the nitrogen degree is about 15 ppm, not practically sufficient to develop crops. How does that change over time? No person is aware of!
Is the Fertilizer in Potting Soil Good or Unhealthy?
Fertilizer in a potting combine is neither good or unhealthy, however it may trigger gardeners a whole lot of hassle. I want producers would both not add it, or be extra clear about their fertilizer.
Right here is the issue with it. Gardeners pay additional for it, and the advertising hype leads them to consider that they now not have to fertilize. That ends in poorly rising crops and disappointment.
The potting soil in the marketplace in the present day can’t be trusted on their advice to withhold fertilizer, as a result of they don’t present the knowledge wanted. In a number of instances, the nutrient ranges are so low that you really want to fertilize as quickly as you pot up a plant.
Assume that any fertilizer within the potting combine provides no actual worth to the plant. That is very true of natural fertilizers since they’re very slow-release merchandise. Fake there is no such thing as a fertilizer within the potting soil.
What do you have to do? Do what I do. I all the time water with a fertilizer resolution at about 100 ppm nitrogen. I ignore any fertilizer that will have been added by the producer.
Fertilizing Seedlings
Numerous the seedling beginning mixes additionally embrace fertilizer, however they’ve the identical drawback as mentioned above. It’s added at very low ranges. Fertilize seedlings as quickly as you see the primary true leaf. I fertilize with the primary watering, even earlier than the seed germinates.
