If you have a vacant lot, slope, field, or a large bare area you want to “naturalize”, here are some suggestions. VARIETIES: Choose either prepared wildflower mixes, or the individual varieties you want. Individual varieties should be chosen based on conditions in your area. For example, drought tolerant species should be chosen for dry summer climates. You can also choose mixes or varieties for a specific purpose, like attracting bees or conserving water.
When to Sow:
The best time to sow in your area depends on climate and precipitation patterns. Perennials generally need a cold, dormant period, called vernalization, before germinating, and annual seedlings will not survive cold climate frosts. Therefore, the ideal time to sow is early enough to take advantage of cool, moist weather, but late enough to avoid killing frosts. In COOL CLIMATES with winter freezes, sow annuals, perennials, and mixes in the spring, 1 to 2 weeks before the average last frost. A second option is to sow half the seed mix 4 weeks before the average last frost (hoping the last frost is earlier than usual), and then sow the second half a week or two after the average last frost (just to be safe). The latest spring sowing date should be early to mid June. After that time, conditions will probably be too warm and dry for germination and establishment. In MILD CLIMATES, sow seed during the cooler months, generally October through March. This will ensure an early display of annuals in the spring, and cool weather for germination and establishment of perennials.
How to Sow:
If you happen to have an area with very fertile soil and ideal weather conditions, broadcasting the seeds may produce desirable results. However most of us have to put more effort into establishing a 'natural' flower patch. Prepare the soil by removing weeds, working in organic matter, and leveling the soil to a desirable grade. Thoroughly mix the seed with some material that looks different than the native soil (i.e. sand), and spread the mix evenly over area to be planted. Sand will make it easier to tell where you spread the seed. With a wildflower mix, it can be nearly impossible to tell which seedlings are flowers, and which are weeds. If you sow a pinch of seeds in a container of potting soil, you can then compare the flower seedlings with what sprouts in the garden.
Seeds must be kept moist until the majority of the seedlings emerge. This may mean watering once a day, twice a day for short periods of time, or every other day, depending on how fast your soil dries out and how much natural precipitation you get. You don't have to water deeply, just enough water to moisten the top quarter inch of the soil surface containing the seeds. Once the seedlings emerge, water less frequently and a little deeper. If you continue to water just the surface, roots will stay on the surface. Encourage deep roots by watering deeper each time you water.
As the seeds begin to germinate, pull the seedlings you know are weeds. Continue to pull weeds frequently as your flower area continues to grow. If done on a regular basis, you will eventually have very few weeds to pull and lots of flowers to admire. Some gardeners have had success with first watering a prepared area in order to bring up the weeds, then eliminating the weeds before sowing the flower seeds.
How far will your seed go?
The less square footage you cover, the more dense the plants and the more impressive the effect, but keep in mind that seedlings which emerge very close to each other will compete for light and water, so some thinning may be necessary to encourage larger plants and flowers. In most cases, about 25 seeds will cover 1 square foot.