She sells sea shells down by the seashore and she can sow seed down by the sea shore also. Your standard all American vegetable garden does not fare well at the ocean side. The winds are at times very strong, too heavy for most plants. The soil structure is degraded by persistent exposure to ocean salts. The sodium draws moisture from plants and burns roots as it leaches nutrients. But you can still grow many common vegetables as well as some not so common ones down by the sea shore.
Raised beds are one method. The beds are filled with suitable soil and lots of organic compost that has not been laden with salts over centuries of bombardment from the sea. The soil in raised beds warms up more rapidly than the ground level soil does. The raised beds are easier to cover from the salt spray which in high winds will carry much further than you would imagine.
So long as the bed is somewhat sheltered from high winds and ocean mist care of the vegetable garden differs litlle from conventional gardens.
You can also side step the costly and labor intensive raised bed projects and grow vegetable gardens in existing soil. You should dig down, remove the top layers of soil to a depth of 8 - 12 inches to rid yourself of the saltiest soils. After you've removed the salt laden soil work in organic compost and top soil, a little peat wouldn't hurt either to bring the garden back up up it's original level.
The presence of the compost not only adds plant nutrients, it enhances the porosity of the soil improving drainage and nutrient levels. Prior to placing any plants or seeds in the new garden saturate it heavily and persistently for about a week with fresh water to flush down any trapped salts. The salts should be forced by the fresh water to a depth where they can not damage the tender young roots of any new plants or seedlings you add.
Even though you've taken all these steps to provide a healthy cleansed soil , your plants will still get a much higher level of salts that they would in a vegetable garden further inland. The salt is in the air by the seashore and salty mist, even though we do not always perceive it, is present in the absence of sunlight even on a still night, the salty brine flows in with the mist.
Choosing plants that are suitable to your zone is another step. But even more importantly choose plants that have a higher than normal salt tolerance.
Tomatoes are the most popular vegetable grown in North America, but most varieties are overly salt tolerant. They can be grown on the seaside but not as successfully as further inland. Sea Shore Tomatoes are best grown in containers or raised beds.
Cool season crops fare better than warm season crops by the sea shore Brassicas and cruciferous plants - Plants such as Asparagus, Beets, Kale, Spinach do well. Plants such as solanaceous plants tomatoes, peppers, potatoes do not do as well but are workable.
Don't even think about corn it does not do well at all near salty wind. The same can be said for radishes and beans.
There are also vegetable plants that evolved near the sea and need no special treatment.
Samphire aka Glasswort is a relatively unkown vegetable that grows by the shore line. It looks and tastes somewhat like Asparagus but actually flourishes in salty soil. In fact, if not being grown by the shore it needs to be watered with sea salt solution.
Sea Kale is in the Brassica family. Like true kale it produces edible, nourishing and tasty foliage. Unlike true kale it also produces edible shoots , roots and flower heads. The shoots have been compared to Asparagus, the foliage is like a cross between spinach and cabbage and the flower heads when permitted to develop are similar to broccoli. It grows near the sea and needs no psecial treatment in sea side vegetable gardens.
Oyster Leaf Sometimes called sea bluebells grows wild on the shores of Scotland. It fares best in cool climates. It is grown for its thick succulent leaves which are very flavorful. Its taste has been compared to oysters and mushroom. It requires cold stratification to germinate and their germination is unreliable. If you decide to try this plant be aware that although it grows very well in cooler sea shore areas it can be difficult to get established.
Sea beets - a shoreline plant that is considered the undomesticated ancestor of common beetroot, sugar beets, and Swiss chard. It is a perennial plant that reaches about 1 foot in height. It tolerates high levels of sodium in its environment. It is grown for lush spinach-like foliage, which many chefs prefer to actual spinach. Unlike true beets the roots are not eaten.
Seaberries aka Sea Buckthorn. Sea berry is a little known European Berry. It is very hardy and grows on almost any soil type. It is drought-tolerant once it is established, seedlings however require consistent moisture. Seaberries are hardy in zones 3 - 7, they resemble citrus in taste and composition and are a tad tart. The berries are the size of a large blueberry and have a citrusy flavor, in fact Europeans use sea berry juice as a substitute for Orange Juice.