How to Plant Wildflowers in the Spring, Summer and Fall

Identify the Correct Wildflower Planting Time for Your Area
Spring or Summer Planting Wildflower Seed in Warmer Climates. If you live in a heatwave-prone area where grass lawns typically turn brown in the summertime, wildflowers should be planted in early spring. This will prevent young plants from being exposed to excessive heat during their first season of growth. When planting seeds in warmer climates with intense summertime heat, it's important to plant your wildflowers in early spring. This will allow your perennial wildflowers to become established under stress-free conditions, making for stronger and longer-lived plants. Annual wildflowers will bloom before intense heat arrives and threatens to fade their color. While there are a few practices that can help all plants do better in excessive heat, such as prudent watering, mulching and providing shade, many of these methods don't make much sense for wildflower plantings - especially meadows and large areas. For gardeners living in these climates, choosing native wildflowers and/or drought-tolerant species and mixes will bring the best results.
Fall Planting Wildflower Seed in Warmer Climates. In warmer climates, sowing wildflowers in fall allows you to take advantage of the ‘Rainy Season’. Putting Mother Nature in charge of watering your seeds means one less thing that you’ll need to worry about! Another advantage to fall planting in the south is that your seed will germinate during the most optimal temperatures. Spring plantings can be challenging in areas that experience very warm spring and early summer temperatures, which can sometimes be too hot and cause stress to young, tender seedlings. Young plants that avoid early stress will develop into strong adult plants that are more resilient to stressful weather events in the future. If you live in a warm climate that still experiences frosts, you'll want to time your planting to be about 60-90 days before the first frost arrives. This will allow perennial wildflowers an opportunity to grow strong enough and establish root systems that will endure. If you live in an even-warmer climate, you may choose to 'winter sow' your wildflowers. Even though the ground doesn't freeze and harden, you can still take advantage of the dormant season by sowing seeds in January or February. You can expect your seed to pop up (germinate) in 2-4 weeks after planting. This is a great way to take advantage of the natural precipitation that winter often brings to the warmest zones.
Spring or Summer Planting Wildflower Seed in Colder Climates. When planting seeds in cold climates that experience snowfall and freezing temperatures, you must wait until after all threat of frost has passed. Even after warm weather arrives in spring, there is still a lingering danger of 'late spring frosts' that can kill off freshly-sprouted seeds and young plants. The greatest threat to spring-planted wildflowers in cold climates is late spring frosts that can kill tender young seedlings. To avoid the risk of a cold snap harming your planting, it's best to consult a last spring frost date chart for your area. This nugget of information will tell you when it is safe to plant. Even after the risk of frosts has subsided for the season, you'll still want to wait for the soil and air to warm up enough to provide favorable conditions for your plants to grow without being exposed to stressful conditions. For fast growth and strong, healthy plants, your best bet is to wait for your soil temps to reach a minimum of 55 degrees F.
Fall Planting Wildflower Seed in Colder Climates. If you live in an area that experiences cold snowy winters, and the ground freezes for more than 60 days, fall seeding is a great plan. Because of your shorter growing season, you’ll get a “jump start” on the following season and should see color 2-4 weeks sooner than a more traditional spring planting. The most important step when sowing seed for fall planting, is to be sure that it’s truly cold enough. You must make certain that the ground temperatures have cooled enough so that when you finally sow, there is no chance of the seed germinating. Yes, that’s right…You definitely don’t want the seed to begin to sprout! Otherwise, those tiny wildflower shoots will simply die off as soon freezing temperatures arrive. In cool climates, the ground temperatures for fall planting wildflower seeds need to be below 45 degrees. Keep in mind that it will take some time for this temperature drop to occur, especially if you’ve had a warm summer. Think of the soil in your garden cooling down and warming up just like a large body of water does. It’s a gradual change that takes time, regardless of drastic changes in air temperature. Experience tells us that the first hot day we get in spring doesn’t mean we should go jump in our pool or nearby lake; the water temperatures haven’t yet had time to warm up and are still way too cold for swimming! So, remember that the mild days of summer should be long gone before you sow your wildflower seeds, as the ground will take weeks to cool to below 45 degrees. The biggest mistake people make with fall planting in cooler climates is sowing their seed too soon.