What's the big deal about Propagation Thermometers?
Soil Temperature is usually the main determining factor of whether a seed will germinate or not. If you sowed the seeds correctly and they don’t germinate, the incorrect soil temperature is usually the culprit. Note that this is SOIL temperature and not air temperature. This can be accurately measured using a propagating thermometer.
Generally, most seeds like a soil temperature of 23 degrees C. Some seeds have special requirements for lower or higher temperatures, usually depending on when they are grown in the year.
- Tomato, pumpkin, watermelon, rockmelon, zucchini, squash, and cucumber germinate well within 20-26 degrees C.
- Broccoli, cauliflower, leafy greens, carrot, lettuce, beetroot, and radish-like cooler temperatures of 10-20 degrees C.
- Eggplant and capsicum can be difficult to germinate if they don’t have the right temperatures – they generally need between 25-30 degrees C. Usually much easier to germinate in warm humid climates like Sydney.
- For herbs and flowers, generally speaking, 22 degrees C is usually ideal.
TIP: Sowing in pots indoors is the best way to monitor soil temperature, and generally improves success rates.