Eryngium Growing Guide

 

Common Name Eryngium, Sea Holly 
Genus  Eryngium 
Species Multiple (Glitter series are E. planum)  
Family Apiaceae
Life Cycle  Herbaceous Perennial 
Tray Size  125
Plug Care Harden off and plant out or bump up into larger cells soon after receiving plugs to avoid them becoming stressed or rootbound. 
Netting / Staking Not necessary. 
Temperature Range Hardiness zones 3-8. Grow best at temperatures between 60-70F and struggle with extreme heat. 
Spacing 18-24" - Plants will slowly grow larger with each passing season but rarely need to be divided. 
Soil Preference Well draining soil is essential, eryngium is sensitive to overwatering. After establishing in their new bed they are quite drought tolerant and can withstand sandy, even salty conditions along a coast. 
Day Length Long-day plant. Plant in full sun. 
Pinching Do not pinch. 
When to Plant Plant plugs in spring, after threat of frost has passed. Can be planted later in the season but you won't see flowers until the following year. 
Harvesting Excellent for fresh or dry use. Cut entire stem down to the base of the plant when the flowers and bracts turn blue or white (depending on cultivar). Cut stems should immediately placed in cool water. 
Post Harvest Care Hang upside-down to air dry (Use a desiccant to preserve the intense blue coloration) or use fresh - expect a vase life of 7-10 days and use a floral preservative to maximize vase life. Can be stored in a cooler at 40F which has been reported to intensify the color. 
Diseases / Insects Eryngium is fairly resistant of most pests and diseases, but like most plants can be attacked by aphids. Root rot is a leading issue in poorly drained soils. 
Bailey's Notes Both Blue Glitter and White Glitter will flower first year if planted early in the season, but don't expect much of a show year one. Each year the plants will get progressively larger and produce more stems for cutting. 
Resources

Production of Eryngium 

Eryngium Planum