Salt, wind and sandy soil: gardening near the coast

How salt spray, salty water, steady wind and fast-draining sand affect food gardens on the bays and barrier islands, and what helps.

Salt spray and wind

The Aransas/San Patricio Master Gardeners warn that constant wind, high temperatures and salt together can kill new plants quickly. Because of the prevailing southeast wind, they advise staking new shrubs and trees unless they are planted in a sheltered spot. Trees bent by wind or salt are not necessarily diseased.

An extension plant list for the Texas coast sorts plants by exposure. Zone 1 means areas hit directly by wind and salt spray; Zone 2 means areas with some protection. Edible plants on that list:

Plant	Exposure zone	Notes from the source
Rosemary (upright and prostrate)	Zone 1	Can freeze
Prickly pear	Zone 1	Spineless forms most useful
Common fig	Zone 2	Edible fruit
Loquat	Zone 2	Edible fruit
Citrus	Zone 2	Lower coast only; cold hardiness varies by type
Pineapple guava (feijoa), Barbados cherry	Zone 2	Listed for protected sites

The Master Gardener guide marks fig, pomegranate, Natal plum (edible red fruit) and chile pequin (edible hot fruit) as salt tolerant. Salt-tolerant ornamentals on the same lists include wax myrtle, yaupon holly, Texas ebony, coastal live oak, cape honeysuckle, Natal plum and seashore paspalum for lawns. In practice, put salt-sensitive vegetables on the sheltered side of a house, fence or hedge.

Salty water and salty soil

AgriLife's irrigation water quality bulletin (B-1667) explains that salts build up as water evaporates from the soil and as plants take water up. Signs include plants wilting while the soil looks moist, which the bulletin calls a "physiological" drought, and white crusts on the soil surface. The main remedy is leaching: applying more water than the plants use so salts move below the root zone. More frequent watering, and drip irrigation in particular, keeps more salt dissolved and helps flush it. Bare soil loses more water to evaporation, so mulch also helps.

Vegetables differ in how much soil salt they tolerate. The bulletin's table gives the soil salinity (ECe, in mmhos/cm) at which each crop keeps its full yield and 90 percent of its yield. Higher numbers mean more tolerance.

Vegetable	ECe at 100% yield	ECe at 90% yield
Beet	4.0	5.1
Broccoli	2.8	3.9
Cantaloupe	2.2	3.6
Tomato	2.5	3.5
Spinach	2.0	3.3
Cucumber	2.5	3.3
Cabbage	1.8	2.8
Sweet corn	1.7	2.5
Potato	1.7	2.5
Sweet potato	1.5	2.4
Pepper	1.5	2.2
Lettuce	1.3	2.1
Radish	1.2	2.0
Onion	1.2	1.8
Carrot	1.0	1.7
Bean	1.0	1.5

The bulletin also notes that beet seedlings need soil below 3 mmhos/cm during germination. On tomatoes, salt damage shows as yellowing older leaves and stunting. Aggie Horticulture notes it is rare in the ground but can become a problem in pots.

Sandy soil

Sand drains fast. AgriLife's home vegetable guide says sandy soils need more frequent watering, and that most gardens need about 1 inch of water a week, wetting the soil at least 6 inches deep.
Don't water so much that you push water and nutrients past the roots. Add compost so sand holds more water.
Mulch about 4 inches deep to cool the soil and hold moisture, keeping it 1 to 2 inches away from stems and trunks.

Raised beds and containers

Raised beds and containers let you start with a better growing mix than native sand, and containers can be moved out of the wind or behind a building. AgriLife's container guide recommends a well-drained mix, drainage holes, and a weekly flush with plain tap water to remove excess salts. Before storms, containers are also easier to protect; see hurricane season and the garden. For crop timing, see the planting calendar.

Sources