Many of us are already planning our summer garden. To be prepared, not only are we ordering new types of seed packets, seed trays, and mapping how it'll all possibly fit into our limited garden space, but we're also thinking about the potting soil options already showing up in garden centers. Is it really true that it makes a difference? Experts say that many accounts, yes, it does.
"By using seed starting mix for germination and the early stages of growth before transitioning to traditional potting soil as plants mature, gardeners can provide the right conditions at each stage of growth," highlights Amy Enfield, Ph.D., Senior Horticulturist at ScottsMiracle-Gro. If you expect a high germination rate and hope to transplant seedlings ready to thrive, it's worth taking a look at the science behind the soil.
Seed Starting Mix vs. Potting Soil
"Seed starting mix (like Miracle-Gro® Seed Starting Potting Mix) and potting soil (like Miracle-Gro® Potting Mix) each serve specific purposes," shares Enfield. "Understanding their differences can help gardeners ensure healthy plant growth. While both soil mixes are important tools, seed starting mix is uniquely designed to support the delicate needs of germinating seeds and root growth in young, healthy seedlings."
Texture and Composition
- It's usually very lightweight and has a very fine texture, which provides excellent seed-to-soil contact.
- The goal of a seed starting mix is to provide a growing environment that is moisture-retentive yet well-aerated.
- The fine texture also allows small, tender roots to grow without encountering obstacles like bark or other large particles often found in regular potting soil.
Moisture and Aeration
- Seed starters are carefully formulated to keep seeds moist by balancing water retention and drainage.
- Ingredients like sphagnum peat moss or coconut coir retain moisture levels without becoming waterlogged, while perlite is added to improve aeration.
- This helps seeds have both the moisture retention and oxygen needed to germinate successfully without root rot.
- If you're considering using garden soil, think again. While a mix of organic material and field soil medium might seem like a cost savings, the presence of weed seeds, and excess water makes it far too hard to successfully baby seedlings.
Fertilizers
Seed starting mixes generally contain minimal or no added nutrients, and there’s a reason for that: Seeds rely on their internal nutrient stores to sprout and establish roots. Introducing fertilizers too early can overwhelm fragile seedlings, leading to nutrient burn or stunted growth. Potting soil, on the other hand, often contains fertilizers suited for mature plants, making it less ideal for early stages of growth.
Ease of Transplanting
The structure of seed starting mixes promotes robust root development, making it easier to transplant seedlings without damaging their root systems. Strong roots are essential for long-term plant health and productivity.
How to Make Your Own Homemade Seed Starting Mix
Making your own soil for seed starting isn't that hard (but we can't compare this mixture to the science-back formula used by Miracle-Gro®). Some gardeners prefer a DIY product merely to control the quality of ingredients. As we've already shared, a good mix for seed starting provides a lightweight, nutrient-rich medium that's moisture-retentive and a well-aerated environment for tender seedlings to grow.
You'll need
- 1 part sphagnum peat moss or coconut coir
- 1 part vermiculite or perlite
- 1 part well-decomposed compost (optional)
Instructions
- Combine the ingredients. Mix equal parts of your chosen components in a large container. Adjust proportions if needed to achieve a light, crumbly texture.
- Sterilize your mixture. To eliminate potential pathogens found in outdoor compost, bake the mix in the oven at 180°F for 30 minutes, then let it cool.
- Moisturize the mix before use. Lightly dampen the mix before filling seed trays or peat pot container. It should be moist but not soggy.
