Shrub verbenas or lantanas are hearty perennials that perform well in our coastal environment.
Photo | Judy Stout
Q: We’ve just finished a complete renovation of a house in Orange Beach and now want to do a yard makeover. Your suggestions?
A: First, congratulations! This sounds like a fun project. Without knowing the details of your site, I offer some important considerations and broad recommendations that should include what will work well for you.
Coastal gardening in the South presents special challenges. Soils may be mostly sand with low water-holding capacity, poor nutrient content (especially iron and manganese) and alkaline pH. Frequent high winds move unstable sands around and can even lift the sand into the air, abrading plant tissues.
Winds off of the water and fog can carry salt spray, often some distance inland. Salt deposited on plants can burn and damage plant surfaces, often causing death. Strong winds alone can cause physical damage, breaking stems and branches.
Weather conditions range from periods of very heavy rainfall, leaching nutrients from the porous soils, to droughts, reducing freshwater in soil and leading to saltwater intrusion in root zones. We won’t even mention the occasional effects of hurricanes and tropical storms!
Cold winter temperatures are not usually a problem for coastal gardeners, and we avoid plants that require cold temperatures to flower or set fruit. However, the winter danger is warm winter days followed by sudden drastic drops in temperature.
Summer weather with long periods of punishing high temperatures coupled with high humidity means plants experience the same heat index that we do. Also, unlike more northern areas, coastal summer nighttime temperatures do not fall enough to allow the soil around roots to cool, which increases the potential for heat damage. Therefore, plant selection decisions should include reference to both heat tolerance and cold hardiness.
The United States Department of Agriculture provides a cold hardiness zone map (tinyurl.com/7r5u267) and the American Horticultural Society offers a heat tolerance map for the U.S. (tinyurl.com/ydez8evl). Combining information from both sources, look for plants with Zone 8a-9a cold hardiness and Zone 8 heat tolerance.
Note that the cold hardiness information alone may be misleading and needs to be combined with the heat tolerance of a plant. Mobile and Seattle are both in the same cold hardiness zone, but Seattle is in heat tolerance Zone 3, with an average of only 7-14 days with temperatures greater than 86 F. Many of their best plants would “melt” here in Zone 8!
A good plant catalog, plant labels or your nursery staff should be able to provide this information for any plant you are considering. A helpful online list from Texas A&M contains a limited but useful list of possibilities (tinyurl.com/ybus2v3e).
OK, now we know what plants are generally suitable for South Alabama, but what about the unique conditions of the coast? Characteristics of successful coastal plants may include: natural salt tolerance; protected leaves with waxy surfaces, hairs or scales; low growth form; dense root systems; high growth rates; flexible stem joints; grasslike growth; or sturdy, flexible trunks. Certainly very few plants will have all of these characteristics, but just look around at natural plant communities and observe the wide variety of trees, shrubs, vines and perennials that do just fine.
It is nearly impossible to provide a comprehensive listing of your options in this space, so consider gathering information from multiple sources. Good reference lists and guidelines can be found in “Gardening in the Coastal South” by Marie Harrison and “Garden Perennials for the Coastal South” by Barbara Sullivan. Local annual plant sales such as those at the Mobile Botanical Gardens and Weeks Bay offer many tried-and-true selections (especially natives).
Even the right plant will need careful installation on your site for best survival. Windbreaks and hedges of the most durable trees and shrubs can give protection from wind, blowing sand and salt spray to more tender plants. Buildings can offer similar protection.
Amend your sandy soil by adding good organic matter such as leaf litter, shredded bark or commercial composted animal manure. Use time-release fertilizer but apply conservatively because salts in fertilizers can build up in the soil, increasing salinity and damaging plants. Water-in well and regularly during the first year. Irrigate using drip irrigation (minimizes evaporation) during drought conditions. If irrigation water comes from a well (yours or the local municipal water supply), be conservative. If the drought persists, it may result in saltwater intrusion into the groundwater. A good mulch will help retain moisture in the soil.
YOU ARE INVITED TO THESE UPCOMING GARDENING EVENTS
What: MBG Plantasia Spring Plant Sale 2018 (Free)
When: March 16, 17, 18; Friday/Saturday 9 a.m. to 4 p.m., Sunday 11 a.m. to 4 p.m.
Where: Mobile Botanical Gardens, 5151 Museum Drive, Mobile
Plant list posted at mobilebotanicalgardens.org. Look for the Master Gardener tent and for workshops on proper planting with MBG Curator of Collections Amanda Wilkins.
What: Mobile Master Gardeners Lunch & Learn (Free)
When: Monday, March 19, noon to 1 p.m.
Where: Jon Archer Ag Center, 1070 Schillinger Road, N., Mobile
Topic: Lighting the Garden, Dave Paton
What: Festival of Flowers
When: March 22-25
For more information: FestivalofFlowers.com
Master Gardener Helpline: 1-877-252-4769 or send gardening questions to firstname.lastname@example.org.