Germination Temp
Wildflower Seed Mixture Germination Temperatures
The lazy approach is let nature do its thing, just create the correct conditions for seeds to germinate and all will be well.
Wildflower seeds germinate at different temperatures. Most interestingly, soil disturbance shows us that seeds can lay dormant for years until the soil is disturbed, no matter what temperature or rainfall, the seeds remain dormant. Its DiSTuRBaNCe, that lets in sunlight and DISTURBANCE that agitates the seed in the soil to get its seed coat rubbed and pressurised, so it starts to react to its environment, add water and the coat starts to breakaway, add extremes of day heat and night cold and the coat shrivels and expands. Seeds don’t waste stored energy to breakout, they keep that for growing up through the soil, instead they mostly rely on external forces to break down the seed coat that the least energy is required to start germination.
However Temperature comes in second place to ‘light exposure ‘ alongside another requirement that is Moisture, as many seeds need light to break dormancy.
Exposure to sunlight is the main element that sets off the seed trigger to germinate, no matter how brief that exposure is, provided there is warm soil and moisture, seeds once triggered by light, many species start to want to grow.
Wildflowers can be germinated in the dark, but the brief exposure to artificial light when seeds are removed from storage, or in packing, or when you open the pack in daylight, is enough to trigger some species.
Perennial wildflowers germinate when the soil is well over a constant 9°C degrees Celsius. In late spring and summer higher soil temp’s, perennial wildflowers germinate fast and in flushes when the soil is well over a constant 10°C degrees Celsius. Some species, red clover and Teasel family benefit from high summer temperatures of over 16°C and up. Autumn germination flushes are due to re-wetting, cooler night variations in temperature. Most ‘dormacy broken’ seeds will germinate when the soil is moist and warm to over 10°C, some like Yellow Rattle, we see germinating at lower temperatures.
Seeds sown outdoors onto soil, finds the depth they need as they work themselves into the soil, they also find the correct temperature to halt their downward ingress into the soil. Hence why a crumbly soil seed bed surface is vital.
In-Door Seed Sowing :
Indoors, at soil temp’ above 12°C, most wildflowers will be triggered into growing.
At DBN, we have found over many years, that while wildflower seeds grown indoors with heat will germinate and grow faster, no matter how they are hardened off, those indoor plants are never as hardy as the species that we germinate outdoors. Some may be down to other factors like resistance to slugs, in that we don’t have too many slugs visit the protected crops of wildflowers.
Indoor wildflowers are far more sensitive to watering. Many dislike the heat generated by black plastic pots, more hate the many types of commercial composts especially too rich, not drained enough or those with added bark Mulch (bark being un-treated by heat).
ScaryCrow Says : On a cold misty or better a cold foggy day, early in the morning, get out the hair blow dryer, carefully blow the seed out the window for me.. Squawk… with a blow dryer, hover over the seed so that warm air blows over the seed, but not onto the seeds or they may well blow out the window. The moisture in the air will also travel and ‘Micromist’ the seeds. Remember ‘DISTURBANCE’, the difference in temperatures, cold foggy, then warm air, will help. If you stop for a short break, then when cooled, apply again, repeat three or four times, using dry air for last pass, then sow the seeds indoors. For very small seeds, mix with a few pinches of the intended dry compost for top of the seed tray and then use the Blower., Squawk, Up full, 3 bars, max, blow the seed out the window to me…..