The Q&A Archives: Birch Tree Salt Tolerance

Question: I live on the Venice Canals, 2 to 3 blocks from the beach and where the groundwater is 2-3' below the surface and salty. We get a lot of fog in the summer and it is usually fairly cool and often windy. I have a smallish amount of space in full sun in which to plant three trees. The size of the Whitespire Japanese Birch (only 12-15' wide)looks the most appropriate, but I cannot determine whether it will survive well in the Venice Canals. Can you please let me know? If the Japanese Birch won't live, will either of the other two birch trees, Himalayan White or Duraheat River, grow well?

Answer: Gardening in a location with salty groundwater and salt spray can be a real challenge. Plant root cells contain a membrane which allows water to pass through, but which prevents salt from entering. As the soil's salt content increases, it becomes more difficult for water to pass through the membrane into the root. In addition, if salt levels get high enough they may actually dehydrate roots or cause "salt burn" by drawing water out of root cells.

High levels of soluble salts also cause changes to soil structure, resulting in compacted soils that are problematic for plants. Because salts bind with soil clays, causing them to swell, compaction occurs more frequently in clayey soils than in sandy soils. Compaction causes reduction of pore spaces between soil particles, reducing water and oxygen penetration into the soil, and water drainage from the soil. As a result, water and oxygen availability to plant roots, and consequently plant growth and pest resistance, is affected.

There are some plants that are more tolerant to salt than others, but the Whitespire Birch is not on the tolerant list. Yellow birch (Betula allegheniensis), Sweet birch (Betula lenta), Paper birch (Betula papyrifera), and Gray birch (Betula populifolia) are the only birches tolerant of saline soils and salt spray.

Perhaps one of these birches will be just the right one for your garden.

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