Big Blue Sea Holly (Eryngium)
|Zones||4 - 9|
|Mature Height||28-30" tall|
|Mature Spread||15-18" wide|
|Bloom Time||Early to late summer|
USDA Hardiness Planting Zones
To determine if a plant is sufficiently cold hardy, the USDA created numbered zones indicating winter low temperatures; the lower the zone number the colder the winter.
- If the coldest winter temperature expected in your area is -15°F (zone 5) then any plants rated zones 3-5 will survive the winter temperatures in your area.
- If you live in very warm winter areas (zones 9-11) plants with zones 3-4 ratings are not recommended. The lack of freezing winter temperatures do not provide a time for winter dormancy (rest).