Soil pH is often talked about but seldom fully understood. While it’s important to know what pH your veggies like, it’s also just as important to know why – and how to test and adjust it!
Poblano peppers do best with a soil pH ranging from 6.0 to 7.0. In other words, they like soil ranging from mildly acidic to neutral. This is also the pH range that encourages the best nutrient availability and the most beneficial microorganisms, both of which encourage your peppers’ growth.
Read on to learn about the importance of soil pH and why poblano peppers like the pH range that they do!
What is soil pH?
Gardeners talk about soil pH all the time. You probably remember the term “pH” from high school, although you might not know all the details anymore. Let’s refresh your memory and perhaps dive a little deeper than you did back in the day!
Soil pH determines the solubility and availability of nutrients and minerals in the soil. Like all other pH measures, soil pH ranges from 0 to 14. A pH of 7.0 is neutral; pH 0.0 is the most acidic and 14.0 is the most alkaline, or basic.
Soil pH is, scientifically, “the negative logarithm of the hydrogen ion concentration.” When the level of hydrogen ions increases, the soil pH decreases.
For the purposes of this article, we don’t have to dive much deeper than that into the nerdy stuff. (Although you could argue that caring about pH at all is pretty nerdy, but I digress).
Soil pH ranges from 0 to 14. Soil with a pH of 7.0 is considered truly neutral soil.
A pH ranging from 7-0 is “increasingly more acidic” and a pH ranging from 7-14 is “increasingly more alkaline or basic.”
Soil pH requirement of the poblano pepper plant
Now that that’s out of the way, what soil pH do poblano peppers like?
Poblano pepper plants have a soil pH requirement of 6.0-7.0. This range promotes the best nutrient availability as well as the growth of beneficial microorganisms. Phosphorus in particular is tricky in terms of its availability but is the most available around a pH of 6.5.
Soil pH is vital in terms of the solubility and availability of nutrients and minerals.
Nutrients must dissolve into the soil before they can be sucked up by your poblanos. The majority of minerals and nutrients are more soluble/available in acidic soils.
Phosphorus is “never readily soluble in the soil,” but it is the most available around pH 6.5.
Very acidic soils (pH 4.0-5.0) can cause excessive solubility of minerals that can become toxic to plants in high doses, such as:
A soil pH between 6.0 and 7.0 encourages the best availability of nutrients for plants. Conveniently, that’s also the ideal environment for many beneficial microorganisms.
While some plants may like soil that’s more acidic or alkaline than that, poblanos do in fact (predictably) prefer a pH ranging between 6.0 and 7.0!
How the wrong soil pH can impact poblano pepper plant growth
Now that we’ve talked about the impacts of having the correct soil pH, let’s talk about some of the dangers of having the wrong pH.
Having the wrong soil pH can impact poblano pepper plant growth by causing nutrient deficiencies, lower yields, and stunted growth. It can also cause dull leaves, chlorosis, scorched tips, and more. Overly acidic soil can lead to deficiencies in calcium, magnesium, molybdenum, and potassium. Aluminum and manganese toxicity are also possibilities.
Overly acidic soil can cause deficiencies in:
These deficiencies can result in spindly growth, dull leaves, chlorosis, yellowing of leaves, scorched tips, cupped leaves, and more.
In addition, aluminum toxicity can take place in soils with a pH below 5.5. Manganese toxicity can also take place.
How to measure soil pH
It doesn’t matter what pH your peppers like if you don’t know how to measure it in the first place!
While it’s possible to measure soil pH using a kit, your most accurate option is to send it to a local university for testing. Don’t test it immediately after adding amendments. Test multiple months before planting so you have the ability to amend the soil in advance.
You can test soil pH at home or send it to a university to get it tested for you. It’s best to send your soil to your local university because most inexpensive kits aren’t very reliable. The university will provide you with a form to fill out and a box or container to put your soil in.
Test your soil before you make any amendments. Popular soil amendments include manure, compost, fertilizer, and lime.
The soil test is best used to help you know how to amend your soil for the next growing season, so test your soil a few months before you plan on fertilizing and planting.
The best tool to use to collect soil is a soil coring tool. If you don’t have or can’t obtain one, use a shovel that is chrome-plated or made of stainless steel.
Scrape debris from the surface of the soil. Dig your hole 6-8 inches deep and then take the sample in one stroke from the bottom to the top.
If you have multiple areas with different types of soil, sample them separately.
While slightly damp soil is okay, don’t collect wet soil for your test.
Do poblano peppers like acidic or basic soil?
Since pH ranges from acidic to neutral to basic, it’s important to know where poblano peppers fall.
Poblano peppers like a soil pH ranging from mildly acidic to neutral, between 6.0 and 7.0. This range encourages optimal nutrient availability and promotes beneficial microorganisms.
Poblano peppers like mildly acidic to truly neutral soil, with a range between 6.0 and 7.0.
This range also, uncoincidentally, is the best range for nutrient availability and beneficial microorganisms.
Maintaining soil pH
Once you get the right pH, how do you keep it consistent?
To maintain soil pH, don’t add any soil amendments that can change its pH such as compost or fertilizer.
In order to maintain soil pH, avoid adding any amendments to the soil once you’ve reached the desired pH. This includes organic materials like compost and organic or inorganic fertilizers.
How to increase soil pH?
If your pH is too low, you need to know how to make it less acidic.
The best way to increase soil pH is to add lime. This lime is most commonly found as “ground agricultural limestone.” It works quicker when the particles are ground up more finely. You may have to add more or less lime depending on the kind of soil you’re working with and the original pH of the soil.
The best way to increase soil pH is to add lime.
The most commonly used form of limestone is “ground agricultural limestone.” The finer it’s ground, the more quickly it works. This is because finer particles lead to more surface area.
Epsoma’s Organic Garden Lime is a great option for increasing your soil pH.
The amount of lime that you need to add to your soil depends on the kind of soil and the original pH of the soil. To demonstrate, soils high in clay require more lime than soils low in clay in order to increase the pH by the same amount.
How to decrease soil pH
On the other hand, a soil pH that’s too alkaline can be just as much of a problem!
To decrease soil pH you can add elemental sulfur, aluminum sulfate, or sulfuric acid. Aluminum sulfate works more quickly than elemental sulfur, but elemental sulfur is cheaper. Sulfuric acid is typically reserved for professionals. It’s best to reduce the pH before you plant rather than after.
- Elemental sulfur
- Aluminum sulfate
- Sulfuric acid
Elemental sulfur and aluminum sulfate are great options for home growers. Aluminum sulfate acts more quickly because of its high solubility. Meanwhile, elemental sulfur is cheaper which makes it great for huge gardens.
We’ve had good luck with Earth Science Fast Acting Sulfur with Nutri-Bond, and plenty of our gardening pals swear by it!
Sulfuric acid acts quickly but is not recommended for the home gardener due to its dangers. It’s occasionally used by professionals around established trees.
It’s better to reduce the pH before you plant your poblano peppers rather than after. The amount of material you need to add depends on the kind of soil you’re working with and what your original pH is.