Choosing The Best Soil For Microgreens (the secret to success)

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Every responsible grower understands that achieving great success in the garden depends on soil composition. The dirt under your feet is like the engine that runs your entire operation, for better or worse. And if you want to grow healthy plants, choosing the best soil for microgreens is essential for achieving consistent results.

Because microgreens are delicate and packed with nutrients and antioxidants, quality soil for microgreens provides the necessary nutrients for your plants to be at their peak. The best soil is typically made with a balanced mix of organic compost and peat moss for good structure and sand or perlite for proper drainage. 

small black plastic microgreen tray filled with soil near full trays on windowsill

Whether you’re an experienced microgreens grower or just getting started in this healthy and fun activity, this article dives deep into all the relevant soil information you need to keep your greens healthy. In addition, I provide potting mix recipes tailored explicitly for microgreens and provide comprehensive guidance on drainage and aeration, no matter what type of growth environment your microgreens may need.

Humble Highlights

  • Save money by knowing what type of soil you’ll need for your plants so you can harvest better-tasting and nutrient-dense microgreens.
  • Discover these top 7 soil ingredients for microgreens, so you’ll know exactly what helps your greens reach their full potential harvest after abundant harvest.
  • Save time by learning the 3 main soil mixes for microgreens so you can grow your micros year-round with confidence – even if you’re a beginner!

Soil Composition And Its Importance For Microgreens Gardening

Because microgreens seeds are sowed in high-density trays or pots, soil composition, and general care are essential in proper microgreen gardening. The soil must be moist enough to retain water but not saturated where mold and disease take root. Likewise, the soil should be well aerated through proper ventilation and air circulation. 

soil composition and its importance for microgreens
Microgreens soil should be well watered, not saturated, and properly aerated to provide oxygen a pathway to the young roots.

Microgreens require nutrient-rich, loose, and well-draining soil so their tiny roots can spread quickly yet retain and absorb enough water to keep the plants well-hydrated. A successful microgreens garden also needs good aeration, which means the soil should be lightweight and fluffy with plenty of air pockets for roots to grow.

The ideal soil mix should contain equal parts of organic matter, like compost, peat moss, and a small amount of sand or perlite, to help keep the soil light and well-aerated. 1

It’s also essential to ensure that the pH level of your soil is suitable for the type of microgreens you are growing. Generally speaking, most microgreens flourish in slightly acidic soil with a pH between 6 and 7.

As a good practice, you can test your soil at home with a reputable soil pH test kit. If your soil pH is too high (alkaline), you may need to add some sulfur to lower it. Conversely, if your soil pH is too low (acidic), add some lime or dolomite lime to increase the level. 

Check Lowest Prices On Soil pH Test Kits Here

Having the right soil composition is crucial for successful microgreens gardening. By understanding what type of soil works best for your particular microgreens and adjusting its pH levels accordingly, you can create an environment where your plants will reward you with abundant harvests in just a few short weeks.

Humble Tip:

Of course, you don’t need to bust out your high school chemistry book to create the perfect growing medium. Any suitable organic potting soil is an excellent option for growing microgreens. However, you can take this one step further if you can find soil that includes beneficial microbes and fungi, which help give your tiny micros an edge.

Common Ingredients For Microgreens Soil Mixes

There are several common ingredients found in microgreens soil mixes, including:

  • Peat Moss
  • Sand
  • Compost
  • Perlite 
  • Vermiculite
  • Limestone
  • Coconut Coir 
microgreens soil mix
Whether you grow your microgreens in soil or another alternative growing medium like coco coir, it’s best to try each and see what works well for you.

Let’s briefly discuss these soil ingredients commonly found in microgreen soil mixes. 

Peat Moss

Peat moss is a wetland plant that produces an accumulation of partially decomposed organic matter called peat. It is highly absorbent and provides a lot of air nodules or pockets within the soil. Peat moss also has excellent water-retentive properties, making it ideal for microgreens which require a moist growing bed to germinate and proliferate. 

Sand

Using sand in your microgreens soil mix is beneficial because it helps promote soil aeration and drainage, both crucial components of micro gardening. Sand also helps lighten the soil, making it easier for plant roots to spread and extend throughout the medium.

Compost

Compost is the decomposed remains of organic material, typically made of leaves, grass clippings, and other plant-based materials. Compost can provide nutrition, aeration, and structure to your soil mix.

reusable growing medium for microgreens
Growing healthy greens with abundant harvests start in the soil. If your soil isn’t right, neither will your plants.

Perlite

Perlite is a type of volcanic glass heated and processed to create a lightweight, soil-like substance. It helps reduce the compaction of the soil while still allowing air, water, and nutrients to reach the plants’ roots. Perilte is often used as a soil amendment in traditional backyard gardening to improve drainage and aeration.

In addition to aiding with moisture retention, perlite also helps regulate pH levels in soil, making it an ideal choice for microgreen potting soil mixes.

Vermiculite

Vermiculite is a naturally occurring mineral formed when volcanic rocks are heated in an oxygen-less environment. The main difference between vermiculite and perlite is that vermiculite granules have a honeycomb-like structure allowing them to be even more absorbent while still allowing air and nutrients to enter the soil. 2

what soil to use for microgreens
Vermiculite is common in potting mixes for traditional backyard gardening and is also welcome in your microgreens trays.

When used as a soil amendment, vermiculite helps to improve aeration, water retention, and nutrient availability in the soil. The material also contains trace elements such as magnesium and calcium, which can help increase plant nutrient uptake. 

Like perlite, vermiculite is so versatile it can be used for backyard gardening and potting mixes, making it an ideal choice for improving soil conditions, inside or out.

Limestone

Limestone is a sedimentary rock that is mostly composed of calcium carbonate. It helps to raise soil pH levels by acting as a buffering agent, making it ideal for planting garden beds with acidic soils.

Limestone also helps to improve the structure of your soil to preserve water and nutrients better. So adding limestone to your potting mix is a great way to ensure your microgreens get the right balance of essential minerals and nutrients.

Coconut Coir

Coconut coir, also known as coco coir or coco peat, is a material made from the husks of coconuts. This soilless alternative growing medium has become extremely popular in microgreen soil mixes because it holds moisture exceedingly well while providing excellent aeration and drainage to your young microgreens seeds.

Humble Tip:

Coco coir offers many of the same benefits as soil but without the dirty “mess” soil residue bestows. It is also environmentally friendly and sustainable, discouraging harmful bacteria from growing in your microgreens’ trays. 

However, even though some micro growers swear by it, coco coir has some downsides. One of the biggest is that you’ll need to soak it before using it as the material is high in salt. Another is that it lacks many nutrients you’d otherwise find in the soil. Therefore, an additive solution can, and in my view, should be applied to the roots of your plants for optimal growth and support. 

What Is The Best Soil Recipe For Growing Microgreens

The best soil recipe for growing microgreens depends on the variety of microgreens you wish to grow and the environmental conditions in which you intend to produce them. Generally, the best soil recipe should be well-draining, light in weight, and contain three-quarters organic material along with one-quarter perlite. Traditional soil used in backyard gardens should be avoided when growing microgreens as the density and compaction of this soil discourage the tiny micro roots from developing. 

soil mix for microgreens
Although microgreens grow well in soil, using the same dirt as your backyard garden won’t help them develop properly.

Some soil recipes will work for all microgreens, while others are specifically formulated to suit certain varieties. Most soil recipes consist of a blend of organic materials, such as compost, aged manure, worm castings, peat moss, and a small amount of sand or perlite. 3

Potting Mix Recipes

When starting a microgreens garden, one of the most important decisions you must make is the type of potting mix (or germination mix) you will use. Some of the most common potting combinations include:

  • Light Soil Mix 
  • Heavy Soil Mix
  • Coco Coir Mix
common microgreens
Depending on the type of seeds you sow, your soil mix may impact how well your microgreens grow.

Let’s look at these different potting mixes tailored specifically for microgreens.

Light Soil Mix Recipe

The first recipe we’ll discuss is a light soil mix. These mixes are suited to lighter-weight greens such as broccoli and kale that may not need a full complement of nutrient additives in which to grow sufficiently. 

You can create a light soil mix with equal parts vermiculite, peat moss, and perlite. Vermiculite helps aerate your soil, while peat moss helps retain moisture and adds organic matter.

how much soil do microgreens need
Proper drainage and adequate aeration are necessary components of a healthy microgreen soil structure.

Perlite provides excellent drainage and prevents your soil from becoming compacted and waterlogged. In addition, you can add some organic compost to this soil mix for additional nutrients if desired. 4

Check Lowest Prices For Potting Soil Here

Heavy Soil Mix Recipe

A heavy soil potting mix recipe works best for “heavier” greens, such as arugula or spinach, requiring more moisture and nutrition than lighter greens.

This heavier combination contains equal parts vermiculite, sandy loam, and compost mixed with an optional addition of perlite for extra drainage.

Vermiculite retains moisture without preventing oxygen absorption by your plant’s roots. The addition of sandy loam allows water penetration while providing good drainage. At the same time, compost adds organic matter, beneficial bacteria, and fungi to help break down any toxins in the soil that could otherwise harm your plant’s growth and development.

Check Lowest Prices For Organic Potting Soil Here

Coco Coir Mix Recipe

The final recipe uses coco coir instead of soil as its base ingredient. Coco coir has become increasingly popular among micro growers due to its ability to retain moisture better than traditional soils without becoming soggy or compacted, as other potting mixes are prone to do over time.

microgreens soil
Coco coir is becoming an increasingly popular alternative in the microgreens world. It is light, moisture-retaining, and environmentally friendly.

To make this potting mix, blend equal parts of coco coir with either vermiculite or perlite to provide aeration and drainage, or simply just use coco coir on its own.

Check Lowest Prices For Organic Coco Coir Here

No matter which potting mix you choose when starting your microgreens garden, it’s essential to remember what plants you’re growing to pick the best soil combination suited to their needs. Although you may be able to grow microgreens in any of the above-mentioned soil mixes, with the right blend of ingredients tailored specifically for each variety, you can be sure your microgreens have everything they need to reward you with a plentiful harvest.

Here’s a short video I found detailing the fine-granulated soil mix for growing microgreens. Although some growers prefer soil for its nutrients, other growers may rely on an alternative growing medium like coco coir or even a grow mat in growing their micros.

Whether you use a peat based product for your soil or something else, growing micros comes down to practice and what continues to perform well for you.

Humble Tip:

Interestingly, this video suggests that microgreens don’t need extra nutrients or compost from the soil to grow. Because the growth cycle of microgreens lasts just a few weeks, the actual seed holds much of the nutrients the tiny plant needs before harvesting. However, debate continues on this topic as it comes down to the subjective experience of the microgreen grower, their preference, and what has worked well for them in previous harvests. 

Some micro gardeners swear by soil mixes to help their plants grow, while others, like myself, only use coco coir. I then apply a liquid nutrient additive to my trays via a bottom watering technique, in which only the roots of the plants are irrigated to help prevent mold from forming on the surface. 

The bottom line is that although microgreens may grow in any soil or alternative medium you choose, the actual nutrient content of the plant may be lacking depending on what nutrients are found in the medium. So, as a humble grower, try a few soil mixes, determine which one works best for you, and then stick with it for sustained results. 

Importance Of Soil Drainage And Aeration

Adequate soil drainage and aeration are essential components of a healthy microgreens crop. If your microgreens do not have adequate aeration and drainage, they are susceptible to waterlogged conditions, which can cause root rot, disease, mold, and other problems.

organic microgreen soil
When it comes to watering your greens, your goal is for the soil to be damp, not saturated.

Proper drainage removes excess water from the soil, allowing the roots to access oxygen and take up nutrients from the soil more efficiently. Remember, you’re looking to dampen your crop, not saturate it. So keep your soil or coco coir moist, but allow any excess water to drain quickly. 5 

Aeration further improves soil oxygen levels by allowing air to move into the root zone and provides a welcome chance for your plants to breathe. Plants don’t like their roots to remain soggy. This practice is essential for microgreens as they are extremely sensitive to oxygen levels in their root environment.

Providing adequate aeration also helps promote beneficial microbial life in the soil, which can improve plant health by supplying additional nutrients, improving water retention, and breaking down organic matter like compost.

Finally, aeration helps prevent soil compaction issues that ultimately suffocate your plant, hinder its growth by spreading disease and mold, and even cause plant death if not properly managed.

Humble Tip:

Whether using a soil mix or coco coir, it’s best to grow your microgreens in shallow trays or pots. Shallow containers provide ample drainage so your greens don’t become waterlogged and susceptible to root rot, mold, and other disorders.

Overall, ensuring adequate soil drainage and aeration for a healthy microgreens crop is necessary for the plants to get all the essential elements (oxygen, water, and nutrients) they need to develop. Addressing potential drainage or aeration issues helps create an optimal growing environment for your microgreens, resulting in healthier and more productive crops.

Tips On How To Choose The Best Soil For Microgreens

When it comes to growing microgreens, one of the most important factors is choosing the soil. The type of soil used can make the difference between a successful harvest and a failed one. Three of the most common tips for selecting the best soil for your microgreens include:

  • Your Growing Climate
  • Soil Composition
  • Soil pH
best microgreen soil
Microgreens can be fickle plants. Therefore, knowing your climate, average humidity, and soil composition provides both you and your plants a distinct advantage.

Let’s look at these practical tips to determine how they can help you pick the best soil for your microgreens garden. 6

Growing Climate

The first tip is to consider your local climate and the types of microgreens you plan on growing. Different kinds of microgreens have various requirements regarding soil composition and pH levels.

If you live in a warmer climate, look for sandy loam soil, which will hold moisture and allow for ample drainage. More nutrient-rich soil would be better if you pitch your tent in cooler environments.

Check Lowest Prices On Microgreens Growing Books Here

Soil Composition

Another critical factor is to select a soil blend that contains organic matter, such as peat moss or compost. This mix will provide essential nutrients to the tiny plants as they germinate and help promote healthy growth through harvesting. 7

best soil for microgreens
As a responsible grower, avoid synthetic chemicals when growing microgreens. Their lifecycle is too short of requiring them.

Also, ensure that whatever potting mix you use does not contain herbicides or pesticides, as these could harm your crop. Microgreens are tiny. Therefore, too much synthetic chemicals in the soil or added during the growing cycle can burn and ultimately kill the plants.  

Soil pH

Make sure to test the pH level of your soil before planting your seeds. Generally speaking, microgreens prefer neutral or slightly acidic soils with a pH range between 6-7, depending on the crop you are growing.

You can test the soil pH yourself using a simple soil pH testing kit found online or at most garden centers.

Check Lowest Prices On Soil pH Test Kits Here

By considering all these factors when choosing the best soil for growing microgreens, you should create an ideal environment where your microgreens thrive and prosper from one bountiful harvest to the next. 

Conclusion

As any beginner or seasoned microgreens grower understands, your success starts with your chosen soil or growth medium. As a responsible gardener, it’s crucial to know how the type of soil used to grow your micros can affect their overall growth, including health and nutrient content, while maximizing yields. 

Although microgreens may grow in various soils and conditions, for best results, it’s important to note that the type of soil chosen can depend on the specific plants you choose to grow. Some plants may require a different medium and different soil ingredients than others. 

Generally, an organic-based potting or seed-starting mix is ideal for growing most microgreens, as they provide plenty of nutrients while allowing good drainage and aeration so the roots of these tiny plants can get off to a great start.

Although debate continues on whether micros need additional nutrients during their growth cycle, it may be worth considering adding nutrient amendments, especially if your growing medium is coco coir or a simple grow mat. 

Have you had success growing your microgreens using a different soil blend? Perhaps you love coco coir as your growing medium of choice. If you received value from this article, meet me in the comments below and tell me how you grow delicious and nutrient-dense greens to perfection.

SOURCES

  1. ResearchGate – Role Of Substrate Media In Growth And Development Of Selected Microgreens
  2. Wikipedia – Vermiculite
  3. Wikipedia – Microgreen
  4. ResearchGate – Comparative Study On Nutrients Of Microgreens Cultivated In Soil, Water And Coco Pith
  5. ResearchGate – International Association Of Biologicals And Computational Digest iABDC Vol6 Issue 1 June 2021 78-84 A Study Of Selected Microgreens In Soil-Less Media International Association Of Biologicals And Computational Digest
  6. Penn State University, Extension – Production And Harvesting
  7. University Of Florida, Extension – Homemade Potting Mix

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