What is a seed starting mix?
If you visit a nursery, you will notice that there are two types of seed-starting mixes.
First, they are not cheap. An 8-quart bag typically costs more than you might think, but it does not hold enough seeds to sow an entire tray.
Some seed starting mixes contain unnecessary chemical agents to hydrate the soil or supplements to supercharge your plants.
The reason a seedling doesn’t needExternal leaves to survive is because all the nutrients it needs in its initial stage of life is contained within the seed. It’s like an egg yolk for a baby chick.
A seed does not need anything other than water to germinate. A seedling also does not need anything other than water to grow healthy and strong in the first couple of weeks.
Soil-less seed starting mixes should only contain three ingredients, not including soil.
I was confused when I first learned about plants growing without soil.
The difference between growing a plant from a seed versus a already grown plant is that seedlings have different needs than their adult counterparts. When starting off, seedlings don’t need the same care as adult plants.
The best seed starting mix is one that is made of perlite, vermiculite, and sphagnum peat moss. You can learn how to make this mix yourself below.
Theseed starting blend is made from light and fine-grained materials to help promote the growth of baby roots and prevent the mix from getting compacted in small seed starting cells or containers.
Is seed starting mix necessary?
If you’re wondering why you might need to use a soilless seed starting mix instead of just planting your seeds in garden soil, there are a few reasons.
Garden soil is in the ground and is part of the soil food web, which is an advantage. Garden soil is also ideally well-draining and somewhat forgiving if you let Mother Nature take over.
Because garden soil is typically dense, full of weed seeds, and teeming with microbes, it is not ideal for seed starting or potting. These conditions can lead to problems such as damping off or fungal diseases.
If you want your seeds to have the best chance at germinating and surviving, you should use a seed starting mix when planting them. This mix is designed to give the seeds everything they need to grow into healthy plants.
What’s the difference between potting soil and seed starting mix?
Potting soil is a medium that contains topsoil and a combination of other materials such as bark, perlite, vermiculite, peat, humus, and manure.
A potting mix is a type of growing medium that does not contain any soil. Sometimes, the terms “potting mix” and “growing medium” are used interchangeably to mean the same thing. Be sure to check the label on any bag you buy to verify what it contains.
Potting soil and potting mix aren’t ideal for seed starting because:
- They have a coarser texture than seed starting mix, and you’ll often find chunks of bark in potting soil.
- They don’t drain as well as seed starting mix.
- They’re sometimes too rich in nutrients.
You don’t need to use potting soil or potting mix to start your seeds, but it’s not the end of the world if you do. You’ll just be paying extra for ingredients that aren’t necessary for germination.
If you don’t want to deal with repotting seedlings, you can start them off in a good potting mix that will help them grow strong and sturdy.
What’s the best soil for seed germination?
A soilless seed starting mix is the best medium for growing seeds indoors because it is both fast draining and able to hold moisture.
You can purchase a high-quality seed starter mixture from any store that also sells seeds, or you can create your own mixture at home.
I love creating my own seed starter mix because it is very easy to do and I can change the ingredients to suit my preferences.
I don’t need to have a lot of seed starting mix on hand if I only need it for one seedling tray.
How to make seed starting mix
I made my own soilless seed starting mix because I had a bunch of the necessary ingredients from making other potting soil recipes and because buying pre-made seed starting mix is expensive.
I wanted to make sure that the ingredients for my recipe were easy for you to find so that I could share it with you.
You can find these ingredients at your local garden center or online.
Ingredients
To make your own seed starting mix, you only need three main ingredients:
- Coco coir or peat moss
- Vermiculite
- Perlite or pumice
- Garden lime (only needed if you use peat moss)
Coco coir vs. Peat moss
Sphagnum peat moss is an excellent medium for retaining moisture. It is finer than the coarser and more fibrous sphagnum moss, and can thus hold more water.
Peat moss can be difficult to rewet once it dries out, while coco coir holds moisture better. Peat moss is also acidic, while coco coir is neutral, so coco coir is a better option if you’re worried about your pH levels. Peat moss and coco coir can both be used as base ingredients for DIY seed starting mix, but coco coir has a few advantages. For example, coco coir holds moisture better than peat moss and is neutral rather than acidic.
If you use peat moss, it is slightly acidic, so you will need to add garden lime to the mix to balance it out.
The disadvantages of using peat moss include its slower renewal rate compared to coco coir, making it less environmentally sustainable.
Coco coir is a sustainable way to start seeds, as it is a by-product of coconut processing.
Adding this to your DIY soil mix is a great idea! I love how it makes the mix more consistent. It’s my top choice for adding to my homemade seed starting mix!
Vermiculite
Vermiculite is natural mineral that is brownish, has a granular appearance, and can absorb water. This makes it helpful for re-wetting soil and it is commonly found in soil used to start seeds. This is because it helps the soil retain moisture which is important for seedlings. Vermiculite can help keep soil evenly moist so that you do not have to water it as often.
Perlite
Perlite is a soil amendment that is very lightweight. The white pieces that look like Styrofoam that you see in many commercial potting soils is perlite.
It is useful because it barely keeps any moisture and prevents the soil from compacting. In simpler terms, perlite makes the soil drain more quickly and the mixture less dense (which is perfect for growing seeds).
you can find perlite in many garden centers or home improvement stores, usually in the same section as potting soil.
If you can’t find perlite at your local garden center, pumice is a great alternative.
Supplies Needed:
Remember to grab these items before getting started: seedling mix ingredients, a few other supplies to help you measure and mix everything.
- Measuring container (I usually use a 1 cup measure)
- Trowel or large mixing spoon
- Container for mixing (I use a bucket or my table top potting tray to mix mine)
- Seed starting trays
DIY Seed starting mix recipe
8 parts (pre-moistened) coco coir or peat moss
1 part vermiculite
1 part perlite or pumice
1. Add 1 tablespoon of garden lime per gallon of water if you are using peat moss.
A batch using a one-cup measure will fill one commercial seed starting tray.
How much is a “part”? A “part” is a generic unit of measure for portioning your ingredients. It can be anything from a tablespoon to a cup, depending on how much you’re making.
A part is anything you want it to be as long as you use the same thing each time. For example, this recipe would convert to 8 parts coir, 1 part vermiculite, and 1 part perlite if you used a 1 cup measure as your part.
To create the perfect mix, combine all the ingredients in a clean tub or bucket and saturate the mix with water. Stir the mixture thoroughly with your hands or a trowel until it is moistened, but not soggy.
Add water to the mixture until it can absorb no more. Depending on the type of peat moss, it can absorb 16 to 26 times its weight in water.
This initial step of watering the mix will help keep it moist throughout the seed starting period, as peat moss can be difficult to re-wet if it’s been left to dry out.
To start your seedlings, fill your pots with the homemade seed mix. Add the seeds and, if they need darkness to germinate, sprinkle a thin layer of vermiculite over them. (You can find special instructions on your seed packets.)
When planting perennials, put the plants at the same level they were in the pots. You can save leftover seed starting mix to use next season, or use it as the basis for your potting mix. When planting perennials, put the plants at the same level they were in the pots.
How to mix your homemade seed starting soil
5 easy steps to make your own seed-starting mix 1. Gather your ingredients 2. Mix everything together in a bucket or bowl 3. Stir until the ingredients are well blended 4. Fill your seedling trays 5. Start planting seeds right away
You only need a few ingredients to make your own seed starting mix, and it’s easy to do. You can make a big batch to store for later, or just make small batches as you need them.
I usually make a large batch of seed starting mix and store it in a plastic bucket in the garage. That way, I always have it on hand when I need it.
Storing your leftover DIY seed starting mix
If you don’t want to attract bugs, make sure to store your leftover soil in an air-tight container.
These air-tight lids are great for keeping bugs out and fit on any standard five-gallon bucket.
One advantage of creating your own soil for planting seeds is that you can test different combinations.
Add more vermiculite to the mix if the soil is drying out too quickly, and add more perlite to the mix if it’s staying too soggy.
How to make the best potting mix for transplanting seedlings
We want to increase the ratio of peat moss or coco coir in the potting mix to help the mix retain moisture so our potted plants don’t dry out as quickly.
A basic potting mix is a good starter medium for transplants, but you’ll want to add compost, garden lime, worm castings, kelp meal, or other supplements depending on the nutritional needs of your plants.
Basic Potting Mix Recipe
6 parts sphagnum peat moss (or coco coir)
1 part perlite
1 part vermiculite
Enriched Potting Mix Recipe
4 parts sphagnum peat moss (or coco coir)
2 parts compost
1 part perlite
1 part vermiculite
By adding compost to your potting mix, you will be helping your seedlings and transplants to grow after the cotyledons die off. I recommend starting with well-aged compost, and then adding other amendments that will provide a boost of nutrients as well as increase microbial activity in the potting mix.
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