Hardiness Zones & 7 Native Plants For South Shore of Massachusetts
Imagine planning a camping trip and having no idea about what weather to anticipate. It could be a hot and sunny weekend, you could struggle with rain and wind, or you could be exposed to snow and icy conditions. Without knowing what/how to prepare, you wouldn’t exactly feel great about heading into the wilderness, would you?
This is like gardening without knowledge of the climate zones or US plant hardiness zones.
Hardiness zones were created to help us know what landscape plants can survive in certain areas of the United States. Without this knowledge, planting anything would be a risk, survival would be uncertain, and we’d likely end up wasting a lot of time.
Fortunately, these hardiness zones can help us out. To get to know them a little better, this article will describe what hardiness zones are, discuss in what zone the South Shore of Massachusetts resides, and suggest 7 native plants that are predicted to work well here.
But First, What are Hardiness Zones?
Not all hardiness zones are created equal, which is to say that there are two government agencies that have produced two different climate maps. The 2012 USDA Plant Hardiness Zone Map is generally considered the standard used by gardeners and growers around the United States. It can help us determine what plants are better suited to a specific location.
Then, there’s the National Oceanographic and Atmospheric Administration (NOAA) Hardiness Zones, which use climatic data to show how the hardiness zones have changed, and how they will continue to do so. In the next 30 years, growers around the United States can expect to experience a change in their hardiness zone, as many areas continue to get warmer.
To confuse things even more, there’s also a relatively popular 24-zone climate system that was published in the Sunset Western Garden Book in partnership with the University of California (but we’ll leave this climate zone system for another blog post!).
And, while it’s important to keep the NOAA Hardiness Zone predictions in mind, the USDA Hardiness Zone map can still be used for garden planning now. So, let’s take a closer look at that one.
USDA Plant Hardiness Zones
Plant hardiness zones have been produced by the U.S. Department of Agriculture since the 1960’s. They’ve allowed us to know what plants can survive where we live (without requiring years of experimentation and failures).
Simply put, the USDA hardiness zones map was designed to help us produce a healthy crop. In order to do this, they’ve designed the map to be as detailed as possible. As you probably know from spending time in an urban area before heading to a local lake or river, different locations (even in the same city or state) will experience different average temperatures.
Prevailing winds, slope and elevation of land, bodies of water, and other small shifts in local geography can mean the difference between average temperatures and, therefore, different hardiness zones. A single state can be home to several different hardiness zones (California has 7, ranging from 5a to 11a!).
While the first hardiness zone maps of the 1960’s weren’t as specific and didn’t accurately account for all of these changes, we’ve come a long way since then.
In the 2012 version of the hardiness zone map (the most recent one), the USDA’s Agricultural Research Service partnered with Oregon State University to use an algorithm in order to better be able to account for the variables we just mentioned. Not only was this a more accurate way to develop the map, but they then also double checked with local experts to be sure that they were putting certain geographical areas in the correct hardiness zones.
So, now that we know what hardiness zones are and how they were developed, we can take a look at what the different zones mean and what general areas of the US fall into each one.
How to Read the Hardiness Zones
Each hardiness zone is based on the annual average minimum winter temperature (over a 30-year period). In the USDA plant hardiness map, North America is divided into 13 hardiness zones—zone 1 being the coldest and zone 13 being the warmest.
Each hardiness zone is divided by a temperature of 10 degrees F. So, zone 1 is, on average, 10 degrees F colder than zone 2. Because that would make things too simple, some zones are divided into “a” and “b” subregions, too! This differentiation between “a”and “b” accounts for temperature differences of 5 degrees F.
While the hardiness zones are a great guide for gardeners, they’re not quite perfect. Soil drainage during cold periods, snow cover, and freeze-thaw cycles should all still be accounted for (and the map doesn’t exactly cover this).
Zone 1a and 1b Hardiness Zones: Below -50 degrees F
Zone 1 covers areas like the Yukon and parts of Alaska. Here, plants are extremely tough and adaptable to cold extremes (and also drought). As can be assumed, growing here isn’t for the faint hearted!
Zone 2a and 2b Hardiness Zones: -50 degrees F to -40 degrees F
Only a few areas of the United States are in Zone 2 hardiness zones—namely places like Pinecreek, Alaska and Jackson, Wyoming. While growing in these areas is definitely a challenge, there are some cold-loving plants that thrive in these temperatures.
Zone 3a and 3b Hardiness Zones: -40 degrees F to -30 degrees F
Now we’re starting to get more into the continental United States! Some areas of Northern Montana, Minnesota, and Wisconsin find themselves in these cold climates.
Zone 4a and 4b Hardiness Zones: -30 degrees F to -20 degrees F
More areas of the Northern US are covered by zone 4, including some parts of Maine and New York. Zone 4 also has one of the shortest growing seasons, with the last frost date typically falling on May 15 and the first frost date as early as September 15! However, unlike the colder zones, there are many nut and fruit trees and vegetables that can be successfully grown here.
Zone 5a and 5b Hardiness Zones: -20 degrees F to -10 degrees F
Zone 5 has a slightly longer growing season, typically from the last frost around May 15 until October 15. Some of the areas covered by zone 5 include some areas of Pennsylvania, Indiana, Illinois, Colorado and Nebraska. In zone 5, most vegetables can fully mature before the first frost and most vegetables and herbs do well here.
Zone 6a and 6b Hardiness Zones: -10 degrees F to -0 degrees F
Ohio, Kansas, Missouri, Kentucky, West Virginia, and Massachusetts (some regions)—as well as some parts of Oregon, Washington, and Nevada—make up some of the areas located in zone 6. With an even longer growing season, planting can start as early as mid-March and continue all the way through mid-November. As many plants and flowers (both annuals and perennials) do well in this zone, it’s a very rewarding place for growing.
Zone 7a and b Hardiness Zones: 0 degrees F to 10 degrees F
When we think of zone 7, we’re likely thinking of states like Tennessee, Virginia, South Carolina, Massachusetts (some regions), Mississippi, Texas, and Utah—to name a few. The varieties of flowers, trees, vegetables, and other plants that can grow here seem endless. With a last frost in mid-April and a first frost in mid-October, this zone experiences a longer growing season, too.
Zone 8a and 8b Hardiness Zones: 10 degrees F to 20 degrees F
As the winter minimum temperatures get warmer, the growing seasons get longer. Zone 8 is characterized by its hot summers and a last frost date around April 1 and a first frost date not until December 1! With this much time, most vegetable varieties will have no issues maturing in time and most herbs, fruit trees, and other plants have no issues growing. Many Western states fall under zone 8 (Utah, Washington, Oregon, etc.) as well as most Southern/Southeastern states (Texas, New Mexico, Georgia, Alabama, Florida, Maryland, etc.).
Zone 9a and 9b Hardiness Zones: 20 degrees F to 30 degrees F
California and parts of Florida, Louisiana, and Texas benefit from nearly year-round planting (the growing season is generally accepted to be nine months!). The time that falls between the first and last frosts can be as little as just one or two weeks! While the growing season may be long, some plants and trees don’t do so well in the high heat.
Zone 10a and 10b Hardiness Zones: 30 degrees F to 40 degrees F
Zone 10 moves us out of most of the contiguous United States (aside from some regions of California and Southern Florida) and into Hawaii. Here, there is a year-round growing season and very little chance of frost. There’s even a “second summer” and most growers can get two cycles of summer crops! While many plants can grow year-round, there are some cold-loving plants that can’t tolerate the heat.
Zone 11a and 11b Hardiness Zones: 40 degrees F to 50 degrees F
The rest of Hawaii (as well as some areas like Key Largo and Key West in Florida) are included in zone 11, meaning it experiences the warmest temperatures and rarely experiences a frost. It’s one of the best places to grow citrus, tropical fruits like soursop, banana, and avocado, and ornamental grasses including lemongrass and citronella.
Zone 12 and 13 Hardiness Zones: Above 50 degrees F
While there are some areas of Hawaii that could be considered zone 12, zone 13 is reserved exclusively to Puerto Rico. These warm, tropical environments are better suited for heat-tolerant plants and exotic fruits.
South Shore of Massachusetts Hardiness Zone
Let’s now take a look at the South Shore of Massachusetts. One of the best things about the USDA’s Plant Hardiness Zone Map is the fact that it’s interactive! You can even type in a zip code to find a specific plant hardiness zone.
So, looking at the South Shore of Massachusetts (and using the respective zip codes for each community) we can see that this region is in hardiness zone 6b.
While we just touched on hardiness zone 6, let’s dive into some more detail for hardiness zone 6b.
Hardiness subzone 6b has an average annual extreme minimum temperature of -5 degrees to 0 degrees F. Fortunately for hardiness zone 6 growers, there is a wide range of fruit and nut trees, vegetables, and other plants that do well here.
While it’s important to remember that frost dates are unpredictable and variable, it is helpful to know that, as a guide, the last frost date is generally anytime between April 1 and April 21. The first frost of the year generally falls around October 17 to October 31.
Pro Tip: Downloading an app or checking specific frost dates for your zip code is recommended to get a better idea of when to expect yours. Check The National Gardening Association website for a great tool!
Considered to be a medium-long growing season, zone 6 tends to be a good zone to grow many different types of shrubbery, flowers, vegetables, and other plants.
However, being a coastal region, there are some special considerations you should make:
- Sandy soils on coastlines generally lack some of the nutrients essential for growth—pick hardy coastal plants that can thrive in seaside environments.
- Salt-tolerant natives do best, particularly those that have shiny or fuzzy foliage, that can either repel seaspray or trap it.
- Hedges can serve as a block to any strong ocean breezes, and it’s a good idea to incorporate these into the periphery of your garden.
- Similarly, ornamental grasses can help prevent erosion. Some, like American Beachgrass (Ammophila breviligulata) also have a high salt tolerance.
- If you live in or close to a wetland resource area (like a dune or coastal bank), you may be required to get a permit before you do any planting. Check out regulatory requirements for more information.
7 Native Plants for South Shore Massachusetts
With all of this hardiness zone information under our belts, now we can start planning some of our plantings!
Native plants are consistently one of the best things to incorporate into any landscape. Why native plants? Because they are well-suited to your climate region and the specific conditions in your area. As native plants, they’ve thrived with your region’s average temperature, rainfall, and local wildlife. As such, they’ll require much less work from you!
Before planting anything, you’ll want to take your soil type, light exposure, and the size of the mature plant into consideration. This is understandably a lot to consider, but we’re here to help! At JMF Landscaping, we’re familiar with local conditions and can help you plan and design a thriving landscape, wherever you’re located in the South Shore.
Without further ado, here are 7 native plants best-suited for our region!
1. Beach pea (Lathyrus japonicus)
This sprawling perennial vine grows well in dune and beach environments, and actually prevents erosion. The showy pink and purple flowers are smooth and, as the name suggests, contain small peas! While the peas aren’t safe for humans, they are a source of food for animals (mice, birds, and deer). While this may attract unwanted garden guests, beach pea also attracts pollinators.
- Red Columbine (Aquilegia canadensis)
Red columbine is a perennial herb. Reaching heights up to two-feet tall, the herb stands out with attractive tubular flowers (red and yellow) that bloom from March to July. Perfect for rocky cliffs and beach borders, red columbine is a popular perennial. It tolerates shade well, can thrive in a range of soil conditions, and easily regenerates. It is also an important plant for pollinators.
- Beach Plum (Prunus maritima)
The deciduous shrub can reach heights of up to seven feet, making it an easy-to-spot and iconic seaside plant. It grows well in Massachusetts’ coastal areas and its fruit, purple beach plums, ripen in late summer/early autumn and make for delicious syrup and jam.
- Common Boneset (Eupatorium perfoliatum)
This summer-blooming perennial is a sun-loving native that is very well-adapted to southeastern Massachusetts. It’s loved by a range of pollinators, does well in sandy (and clay) soils, and is perfect along the banks of a water garden or a pond.
- Foam Flower (Tiarella cordifolia)
Foam flower is known for its bottle-brush white flowers and toothed leaves. As a clumping perennial, its roots spread rapidly to form dense clumps of foliage, making foam flower a perfect spring ground cover. Foam flower can grow well in part to full shade and thrives in well-drained soil.
- Beach Heather (Hudsonia tomentosa)
This flowering member of the rockrose family is also known as sand heather and wooly beachheather. The small shrub reaches heights of about eight inches and features tiny yellow, wooly leaves and small yellow flowers that bloom from May to July. Although it tolerates sandy habitats, it should be kept away from sea spray.
- Black Grass (Juncus gerardii)
Also known as salt marsh rush or salt meadow rush, this loosely tufted perennial herb forms colonies in coastal areas, but can also do well on sites that are further inland. It has rigid stems that make it a good plant for erosion control and its adaptability to wet sites makes it great for coastal gardens. It’s also a good choice for being planted along a stormwater basin or in an area prone to flooding. The small green-brown flowers bloom from spring through summer.
For some other non-native plant ideas, take a look at our recent blog post. As always, we’re more than happy to answer any questions you may have about hardiness zones or native plants, so don’t hesitate to get in touch. Happy planting!
The JMF Landscaping Garden Center and Nursery carries plants that thrive in the unique climate conditions of the South Shore.