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ildflowers 



on New Hampshire Roadsides 



Thomas ]. Gilligan, P.E. 



The New Hampshire Department of Transporta 

 tion has, for a number of years, included wild 

 flower establishment as part of its highway con- 

 struction program. In addition, the Federal Highway 

 Administration mandates that a portion of monies 

 spent on highway landscaping be used specifically for 

 the establishment of wildflowers. Last but not least, 

 the Department of Transportation, in association with 

 the N.H. Federation of Garden Clubs and local agricul- 

 tural vocational schools, coordinates a formal program 

 establishing wildflower fields throughout the state. 

 With the continued establishment of such sites, 

 NHDOT's Roadside Development Section has used the 

 opportunity to 'refine" the methods used in develop- 

 ing a successful stand of wildflowers. 



What is a "successful" stand of wildflower? Well, 

 originally we envisioned a field of successive color, 

 with every sown species evident year after year and 

 with little or no maintenance involved. We have 

 learned that there is no "pure success" when it comes 

 to wildflower establishment, only degrees of success. 

 No wildflower field has been what we would term a 

 "failure," while no field has been everything we had 

 planned. True to landscaping in general, there are 

 many variables, both within and out of your control. 

 One can faithfully prepare an ideal seedbed, sow a 

 quantity mix at just the right time, get great germina- 

 tion and plant establishment, only to have a summer 

 similar to what we've had this year (one of the driest 

 on record) produce marginal results. 



The Department of Transportation's wildflower es- 

 tablishment experiment began as an occasional field 

 sown out of convenience and eventually evolved into 

 a more formal program. Consequently, the data col- 

 lected does not reflect some preconceived plan to de- 

 fine the last word in wildflower establishment, it is 

 simply a summary of our experiences to date and an 

 attempt to realize the most economical process for an 

 acceptable product. We have established relatively 

 small-size fields throughout the state, using not only a 

 variety of seed mixes, but variations and combinations 

 of established planting techniques. 



SITE SELECTION: VISIBILITY 



Wildflower sites established by the Department of 

 Transportation are located primarily on the Interstate 

 Highway System. Additionally, sites established by the 

 Department in association with local garden clubs and 

 vocational schools are, for the most part, located at 



rest areas, toll facilities and on local highways. Having 

 relatively limited funds for wildflower establishment, 

 careful consideration is given to the location of each 

 site. Site selection in all cases is based on maximum 

 visibility by the motoring public and field sizes are 

 defined by the speed of the passing motorist. Smaller 

 fields are located where speeds are slower (ramps or 

 facilities). Larger sites are established within highway 

 medians and are situated to be seen from both direc- 

 tions of traffic. Consideration is also given to minimiz- 

 ing the visual distraction to a driver by locating sites 

 at or slightly below the driver's eye-level and at 

 angles that minimize side-viewing. 



SITE SELECTION: TOPOGRAPHY, LIGHT, 

 MOISTURE, AND SOIL CONDITIONS 

 Topography, light, moisture, and soil conditions are 

 also considered. Sunny, level well-drained sites with 

 relatively good soil are ideal, but seldom available 

 adjacent to a highway. The Department has estab- 

 lished wildflower sites primarily in full-sun locations, 

 but have also experienced some degree of success in 

 less desirable areas. During the spring of 1993, a num- 

 ber of sites were established on 1-93 and 1-89. Among 

 these sites, one in particular did exceptionally well. 

 This site was located, contrary to accepted practice, 

 on a north face slope that received only partial sun. 

 The summer of 1993 was an extremely dry one and 

 the success of this site was attributed to the fact that 

 its relatively sheltered location was not suited to wa- 

 ter loss through heat and evaporation. That summer, 

 similar sites fared better than those located in 'ideal' 

 situations. 



SITE SELECTION: PLANTING ZONES 

 New Hampshire hardiness zones range from Zone 6 on 

 the coast to Zone 3 in portions of the White Moun- 

 tains. The Department has established wildflower sites 

 in all of these zones. Species for individual mixes are 

 selected relative to hardiness as directed by seed 

 supplier. We are just beginning to realize species tol- 

 erance within New Hampshire zones and hope to have 

 a better understanding of this subject as our data 

 base grows. 



SEED SELECTION: ANNUALS, PERENNIALS, 

 AND BIENNIALS 



The Department has used a variety of seed mix for- 

 mulations over the past few years. These have ranged 



Februarys. March 1994 



15 



