Native plants for a Cape Cod garden

It’s good to know what your soil is made of.  If I was a gambling man I’d bet that it is sandy around here.  As a matter of fact, most soil on Cape Cod is about 85 percent sand, with some silt and clay mixed in.  That is, if you exclude the rocks and boulders, the beach sands, and the clay areas that do exist.  Soil composition is a big factor in what species of plants will do well around here:  It greatly decides the availability of nutrients and water. The pH level is another one.  Chances are that the soil on your Cape Cod lot is acidic.  But there are degrees of acidity – soils may have been brought in, or amended in the past.  Pasture land will be different from woodland.  This knowledge is important if you’re in the business of growing vegetables, fruits and non-natives. 

Red = acidic; yellow = neutral; blue = alkaline (source: Wikipedia)

Most native plants are actually quite content with the soil as is – A large area of the continental United States and most of the land east of the Rockies is acidic.  So, native plants are used to it, and they can stand some variance as long as it is in the ballpark (pH of 6 to 7 is generally OK).  But make sure – there is always the possibility that your property is different. You can buy soil pH test kits for $20 or less.  Alternatively you can get soil tests done at the Cape Cod Cooperative Extension ($2 per sample).  They are open from March to late November: Cape Cod Cooperative Extension soil testing.

As with anything, there are exceptions.  Even with native plants from the eastern United States.  Some spots are actually alkaline because of limestone formations that have leached into the soil.  Over the course of eons, plant species have adapted to such an environment.  If you have some of those species present, they may need a little help.  Aquilegia canadensis (wild columbine) and Jeffersonia diphyla (twinleaf) are examples of plants liking a mildly alkaline or preferred alkaline soil.  In those cases, you need to amend.  I use wood ash for larger areas, but chalk and pieces of cement are excellent if you are working with individual plants or small areas. The latter will leach into the soil over time.

I am less concerned with non-native plants, obviously.  But I understand that sticking to native species is not everyone’s cup of tea.  As a matter of fact, some extraordinary beautiful gardens on Cape Cod have non-native plantings.  Knowing what you have in terms of soil is the starting point there also. But beyond that, non-natives are a whole different animal, in terms of human intervention and support needed.

In closing, figure out what type of soil you have. If you are working with native plants you may not need to do anything.  Do your homework when acquiring plants and be mindful of the exceptions – the plants that may have an alkaline preference.  If you find that you need to amend the soil, try doing it in small measures, and try doing it without commercially created concoctions.  It’s money, and worse, down the drain.