As we approach the winter season and have a couple of months of long, cold nights and short days ahead, it seems unbelievable to think about planting in your garden. However, December is the perfect time to start thinking about sowing seeds for spring blooms! Specifically, December is the ideal time to plan your seed sowing for spring ephemeral wildflowers!
When we think of spring wildflowers, we often think of our cool-season annual species like Mexican Golden Poppy, Scorpionweed, Bladderpod, and Lupine. We see these spring blossoms in the wild, but every year they don't produce equal shows of wildflowers. Why do we get super bloom events some years and sparse bloom events other years? Mark Dimmitt and colleagues at the Arizona-Sonora Desert Museum have collected decades worth of data on precipitation as it relates to bloom events, and this has informed our predictions for blooms in the wild as well as shaped protocols for seeding your yard and encouraging annual blooms at home. Keep in mind that timelines for low desert blooms may be ahead of timelines for blooms in the higher elevation Sky Islands, which tend to stay colder for longer.
For a good bloom event, cool season annuals depend on at least one good rain event of an inch or more to stimulate germination between late September - December. This must then be followed by regular rains that add up to at least an inch per month through March. Additionally, winter cannot be too cold or too warm and windy, and there can't be too much vegetative build-up from a previous wet summer that can shade out seedlings. So many factors to consider! If you want to sow spring annual wildflowers in your garden, these are all things to think about. Temperature and wind are factors beyond our control, but perhaps we can provide moisture if there isn’t enough and remove vegetative build-up to let in some light to encourage our seeds to germinate. While rain can be too unpredictable and inconsistent to guarantee a good bloom of spring annuals in your garden, at least we can mimic the ideal conditions through simulated winter precipitation!
For sowing spring annuals in your garden, we recommend seeding into shallow basins where moisture can collect. Sow seeds at a depth that is twice the diameter of the seed so that the seeds are submerged in the soil media but not buried so deeply that the light cannot reach them. For even distribution of seeds, it can be useful to mix your seeds with some sand or fine soil and then spread the mixture across your garden bed or basin. Then, create a watering schedule that mimics the ideal precipitation outlined above, being sure to start with a deep water to trigger germination, then following up with regular watering a couple of times a week that accumulates to at least an inch each month through March. Watering can be decreased if there is plenty of rain, as the plants always prefer rainwater for the higher levels of nitrogen and less dissolved minerals than groundwater. Watering should be gentle and light, just like our winter rains tend to be.
These techniques work well for our Sonoran Desert Spring Wildflower Mix, and all of the spring annual wildflowers that we carry, including Desert Chia, Wild Heliotrope/Scorpionweed, Bladderpod, Mexican Golden Poppy, and Prairie Evening Primrose. This technique can also work in place of cold stratification for some of the spring-blooming perennial wildflowers we carry, such as Parry’s Beardtongue and Organ Mountain Larkspur. You can purchase these species and more through our website and can be shipped, picked up during open hours, or ordered for a pre-order pick-up event in varying locations.
Info sourced from Mark Dimmit.