Using the correct planting rate is important when growing wildflowers from seed. Our wildflower seed mixes have a recommended minimum and maximum planting rate. The planting rates for some seed mixes are adjusted higher due to the presence of small-seeded, nonaggressive species. In general however, the minimum planting rates are based on 60-70 seeds per square foot, which is usually sufficient to establish a good stand of wildflowers on prepared soil when adequate weed control can be maintained. The lower rate is also suitable for broadcast and drill seeding methods. Maximum planting rates are based on 120-140 seeds per square foot and are recommended for more difficult terrain where adequate soil preparation and weed control are not possible, when using a hydroseeder for planting, and when maximum color is required.
It is important to avoid using more than the recommended planting rate because it can lead to poor results. Our trials have shown that heavy seeding rates can produce a thick stand of annuals with lower diversity than expected. The faster and larger growing annuals outcompete the less competitive annuals, reducing the numbers of species present. The dense annual cover also leads to poor perennial establishment, resulting in sparse plant cover and flowers in the second and subsequent years.
If your wildflower planting has some bare spots after the first year, you can overseed with the same mixture in the spring or late fall. Hand sow the bare spots, or use half the recommended minimum planting rate when overseeding the entire area.