Seed Starting Mix vs Potting Soil: Which to Use
Seed starting mix is sterile and light for germination. Potting soil has nutrients for established plants. Using the wrong one causes problems.
They look similar but serve different purposes.
The Differences
| Factor | Seed Starting Mix | Potting Soil |
|---|---|---|
| Nutrients | None | Has fertilizer |
| Texture | Fine, light | Coarser |
| Sterility | Sterile | Not sterile |
| Best for | Germination, seedlings | Established plants |
When to Use Each
Seed Starting Mix:
- Germinating seeds
- Seedlings under 3 weeks
- Root cuttings
Potting Soil:
- Transplanted seedlings
- Established plants
- Container gardens
The Transition
When seedlings have 2-3 sets of true leaves (3-4 weeks), transplant into potting soil.
Common Questions
Can I use potting soil for seeds? Yes, but dilute 50% with perlite.
Can I use seed starting mix for adults? Yes, but fertilize weekly.
What about “seed starting potting mix”? Read the label. If it has fertilizer, it’s potting soil.
Can I make my own? 1 part peat, 1 part perlite, 1 part vermiculite.
Is coconut coir a substitute? Yes. Sustainable and effective.
Can I reuse seed starting mix? No. Pathogens persist.