Many conditions influence seed germination including internal factors such as age or condition of the seed, and environmental conditions such as water, soil conditions, light exposure, and temperature. Most seeds can germinate in a range of conditions and temperatures, but there is a range of optimal conditions that lead to highest germination rates.
In this article we will primarily focus on germinating root vegetables, lettuces, and peas as these are the most common seeds to direct sow into Avalow garden beds. Direct sowing (sowing the seeds directly in your garden as opposed to starting them indoors or planting starts) requires tactful planning and thinking ahead, as many seasonal plants are sown at the end of the previous season.
Sowing Seeds in Fall and Winter
Seeds require certain temperature ranges for optimal germination and this can vary by seed type. In Sonoma County’s mild Winters, where lows average in the upper 30’s and low 40’s, and highs in the 50’s and 60’s, seeds such as spinach, beets, carrots, and turnips can germinate in late Fall for harvest during Winter and early Spring. Beets, carrots, and turnips have an optimal soil temperature of 60-85 degrees, but they can germinate in soil temperatures as low as 40 degrees and as high as 95.
We recommend to sow and plant your seeds by December 1st, but optimally 2-3 weeks before your area’s average first frost. Although it is possible for seeds to germinate at cooler temperatures it will slow down seedling and plant growth. Plants like lettuces, broccoli, chard, and kale are all frost tolerant when mature, but smaller plants are more affected by frosty weather. Get your Winter garden sowed and planted by mid-Fall to ensure a productive garden all Winter long.
Sowing Seeds In Spring
Slightly warmer temperatures of spring allow for a larger variety of seeds to be directly sown in gardens including root vegetables, peas, and leafy greens. We recommend beginning to direct sow lettuce and peas mid-February, roughly 4-6 weeks before your last frost. You may notice slow growth until temperatures warm as Spring progresses. Spring is when many direct sowed lettuces and root vegetables perform best: the seasonal rains keep them watered and steady mild temperatures allow for large, lush produce to grow.
Sowing Seeds in Summer
Summer in Sonoma County gets warm, often too warm for successful seed germination. Warmer temperatures also make it more tedious to keep germinating seeds moist, often requiring twice daily top watering. For the most part, we don’t recommend planting anything (seeds or starts) past early June. Summer growing plants are best planted in late Spring.
In general, seedlings will need to be kept moist until they are a few inches tall. In warm and dry weather, they may benefit from additional watering on top. When watering plants on top be sure to avoid watering the plant directly, water at the base of the plant only (or next to) until the soil is moist.