In an Outer Banks Garden: Zone of confusion
By Keith Lilly
To make decisions on perennials, shrubs and trees, you need to consider our USDA Plant Hardiness Zone. The Outer Banks is in Zone 8a which means our average low minimum temperature is 10° to 15° F. That’s not to say that low temperatures won’t go below the average – it will fluctuate depending on weather patterns. In Zone 8a, you may think that you can grow any plant you want to . . . but wait, there’s more to consider! Our barrier islands bear the brunt of whatever the ocean throws at us. We and the plants we try to grow here are subjected to salt spray, high humidity, coastal storms all year round, and high temperatures day and night in the summer. You need to take this into consideration when planting in your garden or landscape and choosing the right plants.
The Outer Banks is also divided into naturally occurring microclimates.
The ocean and dune area is directly on the oceanfront – here you are subjected to salt spray, winds, high heat, sandy soil and not too much shade or wind protection. Plants with thick leaves and grasses will survive in this zone.
The inner dune area is farther away from the ocean and has wind and salt sculpted trees; a little bit more organic matter in the soil; and some protection from the winds and salt spray. A variety of plants will grow in this area, but you will need to add organic matter and mulch to the soil. You may also need to provide wind protection and irrigation.
The maritime forest area has a lot more organic matter in the soil and better protection from winds and salt spray. Plants in this area do quite well, if they receive the type of sunlight they require; you will still need to irrigate.
And finally, there is the marsh area at the edges of the sounds where there is good organic matter in the soil. However, the soil may become soggy and waterlogged in low areas. Plant choices here should include plants that don’t mind having wet feet at times.
So, when can I plant? Our average last frost date on the Outer Banks is April 10-April 20, so wait until close to May before planting tender vegetables and annuals. If you live farther south towards Hatteras, the last frost date is April 1-10. You can start planting mid-April.
If you’d like to know more about our microclimates, visit the Outer Banks Arboretum and Teaching Garden in Kill Devil Hills where you can see what plants do well here.
Keith Lilly is a Master Gardener Volunteer SM for Dare County. For gardening questions contact Dare County Cooperative Extension at 252-473-4290 or email firstname.lastname@example.org.
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