If you’re new to growing microgreens or are struggling to find the right microgreens soil mix to make your microgreens grow lush and vibrant, you’ve found the right article. What type of soil to use for microgreens is important.
There’s no shortage of opinions about what works best for microgreens soil. This article is not going to compare all the pros and cons of what is out there. Instead, we’re going to give you the exact recipe for success based on our own microgreens performance and make it so you skip the all the hard stuff to get straight to success.
Believe me, we know how hard it is to figure out what works and what doesn’t. We experimented with so many combinations of soil and boy, did we have some epic failures!
Eventually, we perfected the entire process and in this post, we share the key materials to make your microgreens look (and taste) amazing. They are:
- Peat Moss
- Organic Compost
- Agricultural Lime Powder (not dolomite)
If you want to get the exact recipe of the Girly Girl Greens custom soil blend we make (including one extra ingredient that’s not mentioned in this post), click here to get our PDF download.
Table of Contents
Pre-Made Microgreens Soil Mix
If you’re just starting out with microgreens and want to get some experience with it, you might benefit from choosing a pre-made seedling soil mix. This will make it easier for you to get the basics down.
Continuing to grow microgreens, especially if you’re scaling for a business, will mean that you need more soil. Buying bags of soil can get expensive quickly, so when you’re more comfortable with growing you may be ready to try making your own soil in bulk. This will save you a lot of money in the long-run and gives you more control over the end result.
Something important to remember is that microgreens are seedlings. They do not need sticks or coarse material to grow well. In fact, they can suffer if the soil isn’t fine enough. So if you buy soil to grow your microgreens, make sure it is seedling soil and not potting soil.
Potting soil is more dense and designed for transplants or larger plants that will grow in a pot. Microgreens need the fine, lighter seedling soil to grow optimally.
Now let’s talk about making your own soil.
The purpose of peat moss is to create an airy base for the roots to grow in. It is naturally anti-fungal and works well for a soil base. We prefer Black Gold Canadian sphagnum peat moss by SunGro. It is a responsibly sourced, rich quality peat that is fine enough for microgreen soil.
Any peat moss brand that you choose should be sphagnum peat and ideally OMRI listed (organic). It’s even better if you can find one that is eco-responsible in their sourcing.
What About Coconut Coir?
Coconut coir is made from the husk of compressed coconut fibers. It can also be used for microgreens, but keep in mind that has a neutral pH and retains more moisture than peat. So when you water your microgreens, be sure not to overwater. While this important no matter what soil you have, coconut coir is very easy to over-soak, so just be mindful of that. You don’t want your roots to get soggy.
The other consideration for coir is to make sure that it is rinsed prior to buying. If you do not have washed/rinsed coir the salt content will be too high. This will stunt the growth of your seedlings and lead to very poor results.
If you choose to use coconut coir, we recommend blending it with peat moss to add the advantage of fungal suppression. No more than half coir to half peat moss would be our recommendation. In our own operation, we have seen the best results with little to no coir.
Our favorite brand for coconut coir is Plantonix Coco Bliss. The quality and texture is very good and also consistent with each brick. It is rinsed and has a low salt content.
This is one ingredient that many insist you do not need for microgreens. While it’s true that compost isn’t strictly necessary to grow them, microgreens do benefit from the added nutrients that an organic compost provides.
Our own experiments with and without compost have shown a difference. We always noticed that the greens with compost performed better. They were more vibrant and lush. So if you want to make the best microgreens soil you can, especially if you plan to sell them, choose a quality compost. We recommend about 20% of your soil mix should be compost.
The added bacteria of the compost in combination with the fluffy peat moss create a rich environment where the roots of microgreens can thrive. The compost will help your microgreens reach their potential to impress.
Perlite is made from volcanic glass and is essential to creating good drainage for container soil. Vermiculite accomplishes the same thing, but we find that perlite is more readily available in large quantities for more affordable prices.
Choose a soil-grade perlite (medium thickness) and combine it with your peat moss and compost. Be sure to use enough perlite that it will be effective for drainage, but not so much that the water is disappearing too quickly.
Agricultural lime powder (or lime flour) is necessary to balance out the pH of your soil. Depending on your exact ratios and the brands of your soil materials (compost, peat, and/or coir), the amount you need will vary.
Often, just a small amount is enough to keep the soil in the range where microgreens perform best. We don’t want the pH too low or too high and microgreens are more sensitive to these fluctuations than larger plants. Start with a low addition and increase as needed so you don’t make it too alkaline.
Keep your soil at about 6.0 for the best results. Use a good pH soil meter to determine this after adding water to the batch.
Moisture & Mixing
Of course, no soil would be complete without water. When making your own soil in bulk, you need to use enough water to moisten and activate the growth of the seeds. Avoid making it sludgy or letting it become mud-like.
The amount of water you add should make your soil blend feel pleasantly moist but not sopping wet. This is where you will need to determine just how much you need for the amount you make. If your soil sits for several days before you plant again, be sure to mix it well prior to planting your trays.
Mixing the soil together is much easier when you use a compost tumbler. We have several of these on hand for mixing the soil and oh, what a good investment it has been. There’s no better way to combine all the soil ingredients than by tumbling it.
Many sizes are on the market for you to choose from, giving you flexibility to make the amount you need.
Once you have good soil as a base for microgreens, the greens will reward you with quality because they’re happy. Equally important, however, is the type of grow light you choose. How do you cut through the chaos and get the best light for your micros? This article answers that.
Remember, a good soil base is the key to growing the best microgreens you can. Our exact recipe, including the amounts we use, is available below.
Girly Girl Greens is honored to have been featured among the top 25 blogs for microgreens on Feedspot. Click here to see the full list.
We feel privileged to be ranked as number 7 and look forward to helping others continue to learn from our blog. Be sure to sign up for our email list so you don’t miss the latest posts.