What is a Good Planting Time for Larkspur?

In the Northeast, many of our annual cut flowers are sown in a greenhouse in the spring, and then transplanted into the field or a high tunnel. Some species, however, are tough enough to survive winter in the seedling stage for a head start in the spring. Larkspur (Consolida) is one of these. We recently conducted an experiment that illustrates the effect well. The idea was generated from a chance seedling that overwintered in our high tunnel from fall 2011, and produced great stems in spring 2012, three weeks ahead of our spring-transplanted larkspur.  

To compare the two practices, we sowed two varieties of larkspur (‘Sublime Bicolor’ and Cannes Mix) in the high tunnel on Oct. 24, 2012, and the same varieties in a greenhouse on Feb. 13, 2013. The spring planting was put in the tunnel on April 8. 

The fall-sown crop survived the winter in the high tunnel without secondary protection, and came into flower in early June (see Table). This crop had 13 percent longer stems, but the number of cut stems were comparable. The spring-planted crop flowered about two weeks later (see Figure).  Cannes Mix had slightly higher yields of stems than ‘Sublime Blue’.

The results of this trial indicate that fall direct sowing of larkspur is a preferable method of establishing the crop, as long as high tunnel space is available. If you typically pinch larkspur in the spring to produce multiple stems per plant, you can still accomplish this by putting 2 to 3 seeds per hole in the fall planting. Fall sowing avoids the need for greenhouse transplant production, and if an even earlier harvest is desired, using a low tunnel over the seedlings would probably accomplish that.

Is fall sowing of larkspur also possible in the field? It should certainly be tried: we sowed some outdoors in this trial on October 24, but only a few survived the winter. An earlier sowing date might have improved survival.

Acknowledgements:  I am grateful for the excellent technical help of Priscilla Thompson and the financial assistance of a federal ‘Hatch’ grant for part of this work.

Photo:  Larkspur trial, showing spring-planted plots in front, and fall-sown plants behind.  Photo taken June 10, 2013.

Table:  Effect of planting season and variety on stem length, yield and relative earliness of larkspur.

 SeasonVarietyStem length, cmStems per plant, no.First flower date
 FallSublime Blue723.6June6
 Cannes706June 6
SpringSublime Blue593.6June 17
 Cannes644June 22

Chris Wien

Professor

Chris Wien is recently retired Professor of Horticulture at Cornell University. Contact him at [email protected]