Proper timing is critical for any success, and perhaps no group is more acutely aware of this than farmers. Numerous activities must be completed to promote success in agronomic production systems, but the overarching factor is getting the work done in a timely fashion. For switchgrass establishment, timing plays an essential role in ensuring adequate soil moisture and temperature, at providing the best chance for favorable precipitation patterns, and for minimizing weed competition. Planting date is thus a key management consideration for successful switchgrass establishment (Smart and Moser 1997; Parrish et al. 2008)—and perhaps the subject of some controversy.

A review of the recommended planting seasons for successful switchgrass establishment may prove confusing to the uninitiated. Planting in mid-spring (late April to mid-May) has been recommended in Missouri in order to reduce weed competition and avoid risks associated with high temperature and soil moisture deficits common in summer months (Hsu and Nelson 1986a, b), but timing planting to avoid weed pressure will likely need to vary by region or even by field given differences in weed types and pressures by season and location. Timing recommendations (mid-spring) for Nebraska were similar where atrazine was used for weed control (Vassey et al. 1985). However, other Nebraska researchers suggested early spring plantings would be most successful due to greater morphological development (Smart and Moser 1997). Mitchell et al. (2010b) recommend planting switchgrass 2 or 3 weeks before or after the recommended corn planting date in Nebraska.

In Virginia, late spring/early summer plantings have been recommended in order to avoid cool-season weed pressures and to catch warm soils (Wolf and Fiske 2009) that may be closer to optimum for seed germination (Hsu et al. 1985). Such practice requires planting seed of low dormancy—either by planting aged seed that are after-ripened (Shen et al. 2001) or by using stratification techniques (Wolf and Fiske 2009). However, on-farm stratification can prove impractical for large plantings.

Oklahoma research has shown that both late summer/early autumn and late spring plantings can be successful for upland ecotypes which had fewer weed control issues (Foster et al. 2012). At low latitudes in the southern Great Plains, seedling growth with fall plantings can be sufficient to give upland switchgrass ecotypes an earlier start in spring and may also decrease soil erosion in fields over the winter. However, autumn plantings of lowland ecotypes were not recommended at this latitude (Foster et al. 2012) and winter seedling survival becomes a critical issue as one moves to greater latitudes.

As noted by Foster et al. (2012), late autumn/early winter planting dates have some potential utility for stand establishment. Perhaps one of the greatest benefits of such seeding timings is that they can naturally overcome the dormancy associated with new crop seed—that is, as long as this remains an issue.

From this section the reader should recognize that the data are clear in their equivocation. That is to say site-specific management considerations need to be made for decisions on time of seeding. General rules of thumb would be that late autumn/winter or spring (dormant season) plantings are viable if weed control is manageable; later spring plantings may be appropriate if seed dormancy is low and soil moisture is adequate. Windows of planting opportunity are likely to expand if varieties with high germination rates at low temperatures are commercialized (as, e. g., in Seepaul et al. 2011).