How To Plant Wildflowers

Preparing to Plant

It is extremely important to eliminate any undesirable plants by either herbicide or tillage treatments. Removing aggressive cool-season sod forming grasses and other perennial weeds is a must before planting a site to wildflowers. Several non-selective herbicides are available to do this, with Round-Up being the most popular and least toxic. Always refer to product labels for proper usage of any chemical. 

Planning and working a year ahead allows the best chance to control these problem species as it may take multiple applications of herbicide to completely eliminate them. For cool-season, sod forming grasses; a fall treatment is best followed by additional treatments in early spring (if necessary). Once again, it is imperative to control these plants as they can come back to invade your prairie in future years. The use of a starter fertilizer with slow release nitrogen is recommended. Even though native plants are extremely efficient and do not require much water or many nutrients, having those extra nutrients available to young seedlings stimulates healthy root and vegetative growth. On disturbed sites around new construction or water/ sewer lines; it is very important to add soil amendments. This helps young plants to maintain strong seedling vigor. In areas that demonstrate difficulty in establishment, soil tests are recommended to reveal existing problems.

Repeated light tillage is another option to control undesired plant species. In cases of cool-season sod forming grasses it will take a full season of repeated tillage to get good control before planting. The first flushes of weeds in spring can be taken care of by one or two light tillings to destroy growth before planting. If you are not using a no-till drill to seed with; dead thatch and plant material must be removed by burning, raking, or tillage. Getting the seeds in direct contact with the soil may be the most important factor for success.

Planting

Wildflower seeds vary greatly in their size, shape, and density. It is important to make sure the seeder you select is made to handle these seeds. Large areas (over 1/2 acre) are easiest to plant with a native grass drill. These drills have a special feeding mechanism and agitators to evenly distribute the seeds. They are also capable of planting at a very uniform depth which is crucial. Easy-flow type fertilizer spreaders also can be used to distribute the seed. Smaller areas can be broadcast seeded by hand. Mixing the seed with sand, sawdust, or vermiculite can add bulk to the seed and make it easier to distribute evenly over the entire area. This is especially true with wildflowers. We suggest seeding ½ of the seed over the entire area, and then spread the other ½ in a second pass. This helps to ensure full coverage of the seedbed.

Stock Seed Farms recommends planting into a clean, firm seedbed that is free of clumps for optimum seed to soil contact. Loose soil dries out quickly at the surface compared to firm soil. Seed may also be planted too deep in loose soil. A major cause of failed plantings is improper seeding depth. The correct planting depth of wildflowers is ¼ to ½ inch deep. It is not uncommon for a few seeds to remain on the soil surface. This is a good indication of proper planting depth. Most native grass drills have packer wheels or a cultipacker roller behind them to press the soil around the seeds after they have been planted. After broadcasting, seed must be incorporated into the soil by a light dragging, raking, or harrowing. Pulling a straight set disc lightly over the area will also work.

All this is done to place soil around the seed at the correct depth (1/4 inch). Then it must be rolled or packed to press the soil tightly against the seed and firm the seedbed. A good measure of a firm seedbed is to sink no more than 1/2 inch when walking on it. Straw mulch or erosion control blanket can be used if it is not applied too thick. Wildflowers need sunlight at emergence and may smother if the mulch does not allow light to penetrate. Straw mulch and erosion blanket help to keep the soil moist longer and protect against soil erosion. Leftover seed should be stored in a cool, dry place as heat and humidity can cause germination loss. Properly stored seed can be planted the following year with minimal loss in germination.