Tag Archives: perennials

Everything You Need to Know About Plant Hardiness Zones

Photo of the USDA Hardiness Map (https://planthardiness.ars.usda.gov/PHZMWeb/#)

One concept that’s often brought up in gardening literature and rarely fully explained is hardiness zones. While they are a simple concept, to a new gardener it can be helpful to know exactly what a hardiness zone is and how to find theirs.

What’s a Hardiness Zone?

A hardiness zone is a geographic area that has similar climatic conditions that affect plant growth. In the United States, the most commonly used hardiness zones are those 13 zones found on the USDA Hardiness Zone Map. The USDA map is based on the annual minimum winter temperature.

History of Hardiness Zones

Starting in the 1920s people and organizations in the U.S. began making efforts to create a system of hardiness zones. However, it wasn’t until 1960 that the system we use today was created by the National Arboretum in Washington.  Over the years the map has been revised by the American Horticultural Society, the Arbor Day Foundation, and the USDA. Many other countries employ the USDA hardiness zones or a similar system.

The Current Map

The current hardiness zone map was created by the USDA in 2012. The USDA based the map on temperature recordings that were taken between 1976-2005. It’s digital and interactive, allowing users to enter their zip code or click on their location to find out more about their zone. In the future, this map will no doubt need to be updated. In fact, some believe that it already is incorrect due to climate change. Certain zones may have experienced warmer than average winter temperatures in the past few years.

You can find the current map here: https://planthardiness.ars.usda.gov/PHZMWeb/#

How Accurate Are Hardiness Zones?

First, it’s important to note that though winter minimum temperatures are what hardiness zones are based on they are not the only factor that determines a plants survival in a specific area. Some areas within the same zone may experience low winter temperatures for months on end while others within the same zone will only reach anywhere near the minimum temperature for a couple of days.

Snowfall is another big factor. Snow acts as insulation and if plants are consistently covered it can help them survive temperatures they otherwise wouldn’t. Wind is another important consideration. Think about the areas referred to as “above treeline” in certain sections of the Appalachian mountains (particularly the northeast) even though it may be colder farther north where trees are still present, extreme winds play a huge role in limiting growth in the mountains.

What if I Want to Grow Plants Not Suited to My Zone?

While greenhouses and high tunnels are typically used in modern agriculture to extend the growing season of annual plants you can use them to grow perennials as well. Planting in a shelter like this can allow you to plant species that would need a whole hardiness zone warmer than your area.

Some people have also had good luck planting against large rocks or buildings. These features shelter plants from wind and can absorb the sun’s heat during the day and release it slowly as nighttime temperatures fall.

Lastly, some perennials can be grown like annuals or brought indoors during the winter. Keep in mind if you bring a perennial in during the winter that is typically found in warm climates it probably won’t be quite as productive. You may also need to provide supplemental light unless you have large, south-facing windows.

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10 Reasons to Grow Thyme

German Winter Thyme

Thyme certainly isn’t the most popular herb in backyard gardens but we’re stumped as to why! This little plant has a lot of great things going for it. Check out some of thyme’s benefits to learn more about why it deserves a spot in your garden.

Thyme has medicinal properties.

Thyme may be generally thought of as a culinary herb but it also as a long history of medicinal use. It is primarily used to treat lung and throat issues like colds, coughs, and sore throats. It’s an excellent ingredient for homemade cough drops, soothing teas, and gargles. Thyme can also be used for soothing for upset stomachs.

It’s a hardy perennial.

It’s a hardy perennial. At SESE we offer three varieties of thyme. German Winter Thyme and Creeping Thyme are hardy in zones 4-10 and Summer Thyme is hardy in zones 6-9. If you’d like a low maintenance garden it should definitely be on your list.

Thyme can be started from seed.

While many perennials can be a bit tricky to get going from seed thyme is actually quite easy. It can be started indoors with other garden plants like tomatoes and peppers and set out after the danger of frosts have passed in the spring. It may take a little while to get going but not having to buy transplants may be worth the wait.

It’s delicious.

In the kitchen, thyme is incredible versatile. It can be used in sweets like shortbread cookies or savory dishes like sauces, meats, and beans.

Thyme is beautiful.

Creeping Thyme

Thyme plants a truly beautiful and different varieties offer a plant perfect for every garden. German winter thyme is shrubby and upright while summer thyme is a bit smaller. Creeping thyme is a vining plant that creates an excellent ground cover for rock and herb gardens. Even though they have different appearances all three can be used as culinary or medicinal herbs.

It attracts beneficial insects.

Thyme’s little flowers attract a variety of beneficial insects including native pollinators, honeybees, and predatory wasps.

Thyme makes an excellent companion plant.

It can be planted in with cabbage, potatoes, eggplant, and strawberries. It’s thought that it repels cabbage worms, flea beetles, and tomato hornworms.

It’s good for you.

In case you needed a reason besides its wonderful flavor to add thyme to your recipes thyme is very nutritious. It’s high in iron and antioxidants.

Thyme will tolerate shade.

If you have an area of your garden that’s get’s too much shade to be an excellent vegetable patch you might want to add some creeping thyme. It will do fine in areas that are fairly shady.

It doesn’t need much water.

While you need to water your thyme plants while they’re getting established once they’re mature these Mediterranean plants require very little water. They’re perfect for water conscious gardeners or those in drought-prone areas.

If you’re planning your garden for next year you may want to add thyme to your list! These are just a few of the many reasons this wonderful herb deserves a spot in your garden. What’s your favorite thing about thyme?

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Adding Perennials to Your Vegetable Garden

When planning our gardens we often think of annual food crops. Plants like peppers, tomatoes, cabbages, and sweet corn come to mind first and are the powerhouses of most backyard gardens. However perennials are an excellent addition to any garden. There’s a lot more to perennials than just their longer lifespan.

Why Grow Perennials

You can increase your food production.

Perennials can increase the amount of food you produce and therefore decrease your environmental impact. They’re often some of the first foods up in the garden and sometimes the longest producing. Plants like rhubarb, chives, and salad burnet will help fill your plates with local food when most of your annuals are still just tender seedlings.

They require less work.

Growing more perennials means less time spent starting plants each year. Just keep the weeds back, provide basic care, and enjoy your harvest.

Many perennials require less water.

As they grow for more than just one season they are generally able to develop deeper, more extensive root systems than annuals so they’ll need less careful watering.

They’re better at gathering nutrients.

Another advantage of their well developed root systems, perennials are often able to access nutrients from deep in the soil that annuals cannot. Perennials help bring these to the surface for them and the plants around them.

They improve soil structure.

Their root systems even help improve soil structure which helps not only them but any annuals that you grow near them. The soil health also improves because it’s not being disturbed each year. Nutrients are added through a top down system as parts of the plant die back or you add mulch around them. This process is just like what happens in a natural ecosystem.

How to Get Perennials

Perennials don’t have to be expensive! Browsing catalogs and visiting your local garden store can lead you to the impression that a garden full of perennials is going to be an expensive one. It’s doesn’t have to be though. Many perennial plants are easy to start from seed or divisions from existing plants which can sometimes be acquired for free or cheaply from friends, neighbors, or your local garden club. Ask around!

Southern Exposure Seed Exchange offers many perennial plants and seeds that can get you started without a big investment. Below are just a few of the perennials SESE offers that are easy to add to your garden.


Adding a lot of flavor with little effort, chives are super hardy, beautiful, and easy to grow. Plus once yours get established it’s easy to divide your plants and they make a great gift.


Though not a true fruit, rhubarb is the first fruit like food you’ll be able to get locally each spring. While many garden centers only sell rhubarb plants they’re actually quite easy to grow from seed. You can find a great post on growing rhubarb here.

Perennial Onions

For some, growing a patch of perennial onions is enough to supply all their onion needs without having to start tons of onions from seed each year.


Thyme makes and excellent perennial ground cover with the added benefit of smelling nice and being edible.

Salad Burnet

Often said to taste like cucumber, salad burnet will come up early and feed you long before any actual cucumbers will be available.


A highly sought after medicinal, ginseng takes awhile to grow but is well worth the wait!


Sage is both edible and medicinal and simple to grow from seed.


On top of being a commonly used culinary herb, oregano’s small white flowers also do a great job of attracting pollinators.

Garden Huckleberry

These dark blue berries are one of the few berries that are easy to grow from seed and they make excellent jam. You can read more about them here.


This flower has a lot going for it. Echinacea is not only beautiful but a great species for attracting pollinators and it’s highly medicinal.

Lemon Balm

As a member of the mint family, lemon balm gets established and spreads so easily you may actually want to make an effort to keep it contained.

Don’t be afraid to add a few perennials to your garden this year. They’re quite affordable and have many benefits. Even if you decide you need to change your garden layout most can be transplanted without harm later on.

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