Seed Starting Essentials | Grow Strong, Healthy Seedlings
Understanding a few key essentials for good seed germination can make seed starting easy and successful! With the right soil mix, moisture, and temperature, you can grow your own strong, healthy seedlings!
Seed Starting Supplies - Seed Raising mix, trays, pots or soil blocks, clear domed lid, heat mat, light, watering can and/or bottom water tray
1. Proper Seed Raising Mix
When buying or making a seed raising soil, ensure that the mix is balanced with materials that:
- maintain moisture and
- materials which are porous to allow drainage.
Our ideal mix contains coco coir which retains moisture AND sand and perlite which keep the mix from becoming too heavy. Try our Transition Farm Mix Recipe →
Making soil blocks to sow cucumber seeds with Transition Farm Seed Starting Mix
2. Correct temperature
Each seed has an optimal germination temperature usually between 12-27C with 23C being a sweet spot for many. Maintaining this constant temperature can be difficult, especially when starting our first seeds in Winter. We use a heat mat to achieve this.
Bottom heat helps seeds germinate faster and better. We also use domed clear lids to retain heat and moisture.
In our climate, insuring an optimal germination temperature and a warm ambient temperature with air circulation has provided us with quick germination and strong seedlings.
View our OPTIMAL GERMINATION TEMPERATURE GUIDE
3. The Right Amount of Moisture
Seeds need contact with moist soil—enough humidity to soften the seed coat and spark germination, but not so much that they rot.
Tips for perfect moisture:
- Pre-wet your mix before filling trays.
- Tap trays lightly to settle soil, but don’t over-compact it.
- For bottom watering, set trays into a solid tray with 1–2 cm of water—the soil will wick up what it needs, protecting seeds from disturbance.
- For top watering, use a fine spray nozzle or gentle rose watering can to avoid dislodging seeds.
With bottom heat, check trays often. Lift one side—soon you’ll learn by weight whether they’re evenly moist.
Allow the top few millimetres of soil to dry slightly between watering to prevent algae, fungus gnats, and damping-off disease.
To save room on our heat mat, we often sown seeds in lines and then later, prick them out into individual cells.
4. Correct Sowing Depth
A general rule: sow seed no deeper than twice its width. Check your packet for specifics.
Use your finger, a pencil, or a dibbler to make the right depression.
We cover most seeds with vermiculite—it helps:
- Maintain surface moisture
- Reduce damping-off fungus
- Buffer against temperature and humidity changes
Always read your seed packet—some seeds prefer light and shouldn’t be covered.
Sprinkle vermiculite to cover seeds
5. Light!
Some seeds need light to germinate, while others prefer darkness. Once seedlings emerge, strong, close light keeps them sturdy and upright.
If seedlings “stretch” toward the light, they’ll grow leggy and weak.
Tips for strong, stocky seedlings:
- Paint greenhouse walls white to reflect light.
- Use a shop light or grow light positioned close to seedlings, raising it as they grow.
- If growing in a north-facing window, rotate trays daily to prevent leaning.
- A white sheet or shower curtain can act as a simple light reflector.
Final Thought
With the right seed raising mix, steady warmth, balanced moisture, the right sowing depth, and good light, you’ll give your seedlings the best possible start.
It’s worth the effort of observing and adjusting to find what works for you. There are so many wonderful varieties only available as seed — and the celebration and excitement of growing from seed never grows old!