Gardening is not easy. Have you ever visited a garden in a different part of the country or just toured another state and wondered what you’re not doing right? Many people assume that simply preparing a garden and planting a few flowers and shrubs and watering them religiously will do the trick.
Sadly, nature isn’t made like that. Many other things come into play, especially those that support plant life in different parts of the country. One major one is the planting zone you live in, as this goes a long way in determining the type of plants you can have in your garden.
Before you get excited and start buying all kinds of plants with fantastic flowers and leaves, it is essential to understand the planting zone you live in. This is because all the efforts you put in when gardening might be null and void if the planting zone doesn’t support that kind of plant.
In this piece, we will break down everything you need to know about planting zones in the United States of America and recommend the best plants for each of them. With this information, you are better placed to design your garden with some insight into what can work and what cannot. This is important to manage expectations and help you channel your resources into the right things as you try to develop your garden.
An Overview of Planting Zones in the USA
Planting zones, also known as hardiness zones, are how the USDA divides the whole country based on weather patterns. Initially, the USDA had divided the country into 11 distinct zones but increased the number to 13. All these different sections differ by a 10-degree Fahrenheit range.
Plants can survive in different temperature ranges, and the hardiness zones inform gardeners on the best plants they can choose for their specific regions. In addition, they also bring out an accurate picture of the harshest winter temperatures these regions will experience.
The term hardiness zone is commonly used because the temperature range indicates the area’s extreme winters that test any plant’s tolerance. If you take a plant designed for one hardiness zone to another, the chances are high that it might be shocked by the heat or cold, significantly affecting its growth and might even lead to its death.
This way, understanding this categorization will go a long way to helping you choose and care for the most suitable plants for your location.
Note that hardiness zones are not cast in stone in light of global climate change. In addition, with improved technology, the USDA continually improves its classification by getting more data points and conducting more comprehensive analyses to make the classification more accurate.
Understanding the Differences Between Planting Zones
A 10-degree Fahrenheit range separates hardiness zones. They run from the lowest to the highest possible conditions in terms of temperature. Those in the lower zones can survive the coldest temperatures well the ones in the highest ones are more suited to hotter temperatures.
Note that plants are not exclusively put in a specific planting zone as many of them have a range in which they can survive. For instance, you might find a particular plant suggested for areas that fall between hardiness zones three and seven. Here, they can survive some degree of cold, but only up to a certain extent as scorching temperatures might be too much for it.
If you buy a plant in an accredited nursery or through a reliable e-commerce store, you will notice the suitable hardiness zone indicated in the description. Besides the numbers that differentiate hardiness zones, you’ll also find them highlighted as either a or b. Plants labeled under the tag (a) can tolerate winter temperatures 5 degrees lower than those in tag (b).
Most of us assume that the Northside experiences cold temperatures than the South and Central sections of the United States’ central part. This is an assumption that holds for some areas, but it doesn’t for others. A good example is Baltimore which is on the Southside and has a large part of it in zone 6, whereas Seattle in the Northside having most of its areas in hardiness zone 8.
Gardeners should not only focus on hardiness zones, as plants do not solely rely on temperatures to grow. They should consider other factors, especially when looking for the best plants for each location. Some of them include;
This is the amount of moisture in the atmosphere. Two locations can be in the same hardiness zone but have different humidity levels. Always take this into account, as some plants are suited for high humidity while others can survive low humidity.
High humidity levels slow down the rate at which plants release water through their leaves, while low levels increase this rate. An example is California and Florida, which have parts in their states classified in the same hardiness zone but vary significantly in humidity level.
This is an additional factor mainly brought about by air movement triggered by the ocean waves. Winds are notoriously known for drying out plants, and strong ones can damage them by breaking their branches and stalks. If you live in a place with strong winds, be prudent about the plants you pick, as low-lying shrubs with thick stems are more likely to survive. In addition, consider evergreens that will be resistant to a drying effect brought about by the wind.
Hardiness zones look at the temperature levels in an area, but some other human activities can also increase or reduce the temperatures. A typical example is an urban heat, where you find urban areas being a lot warmer than rural ones.
This it’s attributed to the urban heat island effect. Since these areas are full of buildings and structures, they tend to store heat between these structures, making the temperatures higher than usual. If you rely on the temperature classification of hardiness zones, it also helps to look at the urban heat effects before selecting the right plants.
Rain is an important thing when planting anything as it increases the amount of water that a plant can absorb. Look at information about how much rain your area receives. Note that too much rain is not necessarily good as some plants are better off with less rain. If your area is very wet, lean towards the wet tolerant plants or find a way of improving drainage so that you don’t have a lot of water soaking the plants’ roots.
Importance of Understanding Your Planting Zone
Here are some of the benefits of knowing your planting zone;
1. Invest Prudently
Gardening is not cheap as some exotic plant varieties cost a lot of money. This does not even consider the amount needed to take care of these plants until they grow. Look at plants as an investment and buy the right ones. If you invest wisely in plants, they will last a lifetime, and you will be required to do very little throughout their lifetime. This way, always invest in plants better suited to your hardiness zone.
2. Better Insight
When you walk into a nursery to buy a plant, you’ll find them labeled with lots of information, most notably the hardiness zone they are suited for. As a gardener, you are better off with more insight into the plants you’re buying, as this will help you make better decisions as you move along.
When you know your hardiness zone and other factors that affect plant life, such as humidity, wind, and urban heat, you will be better placed to stock the right plans. Before you plant anything, take your time to study some of these factors to gather enough insights needed to develop and nurture your garden.
3. Improved Care
Plants need oxygen, water, and food to grow. However, giving a plant too much water won’t necessarily make it grow faster or become healthier. Plants need an optimal environment that allows them to thrive. As a gardener, you want to make the environment as optimal as possible for your plants.
You don’t have much control over environmental factors, and the best place to start is selecting plants suited to your hardiness zone. This makes your job of nurturing them easier as the environment will do most of it.
Once you gather insights about plants’ hardiness zones and other conditions required for them to survive, you’ll start understanding which ones are healthier and more receptive to certain conditions.
With time you’ll notice that some tend to either do well when the temperatures rise while others dwindle and struggle during the same period. Such insight is vital as it helps you to diversify your garden and start experimenting. You’ll understand what works for you and can have the leeway to try out new species that might not have been listed under the recommended ones for your hardiness zone.
USDA Plant Hardiness Zones
Today, the USDA planting zone map is interactive and allows gardeners to narrow down to specific locations and find the information they need. However, the map changes from time to time to reflect climate changes, and always check with new classifications to ensure that you’re giving your plants proper care. The current 13 planting zones and their details are listed below;
1. USDA Zone 1
This is the coldest planting zone in the United States of America. Its temperature range is between negative 60 negative 50 degrees Fahrenheit. It is further divided into zone 1a and zone 1b. Zone 1a experiences temperatures between -65- and -55-degrees Fahrenheit, while 1b ranges from -55 to -50 degrees. This zone mainly covers areas between Northern and Central Alaska.
Note: Subclassification (a) is cooler than (b) for every zone.
But can you grow anything in these sub-zero temperatures?
Plants that are meant to survive in this zone are tough and can adapt to cold extremes. Most of them are xeriscape, meaning they can resist extreme drought. Understand that gardening in this zone is not easy, and you must be ready to go over and beyond to ensure your plant survives. Plant choices are very limited, and you must pick ones that are made for these harsh conditions.
Despite these low temperatures, the plants recommended for this zone can still be classified as perennials and annuals. You don’t have much to choose from, but the first place to look for are the natives to these cold areas. If a plant can survive on its own in the wild in such areas, the chances are high that it will survive in your garden.
Native annuals should be your go-to option since you’ll find a couple of them. However, perennials are more long-term, and they can survive throughout the year. Some common examples include yarrow, false spirea, cranesbill, delphinium, creeping jenny, and lily of the valley.
Some plants are not native to these cold regions but have adapted over the years and can survive the harsh temperatures. While these plants may not have the hardiness of the natives, they can adjust well if given time but will require a little more tender care for them to thrive.
A few things you can do to support them include giving them supplementary water, sheltering them from the harsh conditions, and mulching them to protect them from heavy winter. Some of them include seal lavender, seaside golden roof, sweet flag, wild mint, stinging nettle, astilbe, and blazing star.
Remember that most areas in this zone have a lot of wildlife and have the proper fencing to protect your plants from animals such as mice, rabbits, and deers.
2. USDA Zone 2
Zone 2 is not all that different from zone one, and extremely cold temperatures are experienced here. The ranges here are between -50- and -40-degrees Fahrenheit. The only parts in the USA that fall under this zone are Alaska’s Central and Northern parts. A few areas in the coastal side of Alaska also fall under zone 2b, which ranges from -45 to -40 degrees.
All the plants listed above under zone 1 can survive here since temperatures are a tad better. However, the slight increase in temperatures brings a few more plants into the equation, and gardeners have more options to choose from.
Examples of plants you can grow in Zone 2 include;
- Bog rosemary
- Iceland poppy
- American cranberry bush
- Lead plant
3. USDA Zone 3
This hardiness zone mainly covers the states that border Canada. They include North Dakota, Minnesota, Wisconsin, and Northern Montana, among others. Some sections of upstate New York and New Hampshire can fall into zone 3b at times, which ranges from -35 to -30 degrees Fahrenheit.
The temperate range for this zone is between -40- and -30-degrees Fahrenheit. Due to the low temperatures, gardening here is tricky since the growing season is very short.
This way, plants have a limited window to grow to a point where they can be resilient enough to withstand the harsh conditions. However, compared to the other two zones, the options increase here, and many more plants can survive in this zone.
A few examples of plants that can do well in Zone 3 include cherry, pear, crabapple, and apricot. Perennial herbs that are suited for this zone include peppermint, chamomile, French sorrel, and parsley. Vegetables include squash, potatoes, asparagus, cucumbers, and radishes.
A critical tip for gardeners in this zone is to consider sowing seeds indoors due to the limited growing period. This increases the chances of the plants surviving since you only transplant them once they hit a certain level of maturity.
This zone is also perfect for setting up a greenhouse which allows you to grow food throughout the year. Look at the ratings of the plants and trees you choose and lean towards those labeled as “very hardy” as they can easily withstand the harsh winters.
4. USDA Zone 4
Temperatures in this zone range between -20- and -30-degrees Fahrenheit. Like all the other zones, this one is divided into Zone 4a and Zone 4b. Their ranges are between -25 and -30 degrees and -20 and -25 degrees, respectively.
Zone 4 has one of the shortest planting seasons compared to the rest, as the first and last frost dates are between May 15 and October 1. Understand that these frost dates vary significantly and always stay up to date with the current ones. Some common states with Zone 4 regions include Iowa, New Mexico, Utah, Wyoming, Vermont, Washington, Oregon, New Hampshire, Minnesota, Idaho, Nevada, New York, Maine, and Michigan.
Most states have more than one zones due to topographic and climatic differences.
Many plants and vegetables can thrive in zone 4, including;
- Nut trees
- Fruit trees like apple, pear, and cherries
- Any “hardy” tree
- Vegetables like beans, cucumbers, tomato, pepper, corn, and squash
Understand that only sour cherries can survive in this zone, as the sweeter ones require warmer temperatures like those in zones 5 and 7.
5. USDA Zone 5
Zone 5 experiences temperatures between -10- and -20-degrees Fahrenheit. Some of the areas with this zone include Colorado, Nebraska, and Iowa, being the primary representatives. Others include Northern Illinois, Indiana, Massachusetts, and Northern Pennsylvania that experience zone 5b conditions.
Most vegetables will thrive in this zone. It is also known as a medium growing season zone, which is a bit lower than some with higher numbers. As a result, most vegetables have enough time to get to maturity before the first frost.
The first frost date is typically October 15 and the last one being May 15. People living in this zone should always watch out for frost warnings as they defy these base dates and come earlier than expected.
Some of the plants that will do well here include;
- Native pawpaw, warren plum, and pink lady apple
- Most vegetables such as beans, corn, cucumbers, among others
- Nut trees such as walnut, chestnuts, hazelnuts
One tip for this zone is extending the growing time using raised beds that keep soil warmer. It is also advisable to start seeds indoors for more than six weeks before the frost date to give them better conditions while they are still younger.
6. USDA Zone 6
Zone 6 experiences temperature ranges between -10 degrees and 0 degrees Fahrenheit. It belts across the eastern border of Colorado and New Mexico, through Kansas, Missouri, Kentucky, Illinois, Ohio, West Virginia, Southern Pennsylvania, Maryland, New Jersey, and Connecticut. You will also find some areas of Washington, Oregon, and parts of California and Arizona.
The average first frost date is between October 17th and 31st, whereas the last frost date is between 1st and 21st April. Some of the plants that thrive in this zone include;
- Apple trees like Honeycrisp, Gala, and McIntosh
- European pears
- Various peach tree varieties
- Cherries, blackberries, and blueberries
- Walnut, pine nut, pecan, and chestnut
7. USDA Zone 7
The temperatures here range from 0 to 10 degrees Fahrenheit. Areas under this zone include New Mexico, Northern Texas, Oklahoma, Arkansas, and North Carolina.
Gardeners in this area enjoy a relatively long plantings season which lasts for about eight months. The first frost is experienced around November 15, while the last frost being seen around April 15. Many crops will do fine in this zone.
When planting vegetables, it is advisable to start setting seedlings indoors before the first frost. This gives you more time and lets you harvest vegetables like broccoli and carrots twice. This technique has worked well for plants like; beans, tomatoes, onions, kale, peas, peppers, spinach, squash, and Brussel sprouts.
Both perennial and annuals can do well here, which makes it an ideal area for flower planting.
8. USDA Zone 8
Areas under this zone have mild winters, with temperatures ranging between 10- and 20-degrees Fahrenheit. They have longer growing seasons and temperate summer climates, and cool nights. This combination makes them ideal for all kinds of flowers and vegetables. The areas under this zone include the coastal regions of Washington, Oregon, and Northern California. It also extends to Central Texas, Mississippi, Alabama, Georgia, and North Carolina.
With the proper planning, you can plant your favorite garden vegetables even twice a year. You can do this by sowing them in early spring for harvest in early summer before sowing again for harvest in early fall.
The plant variety for gardeners in this zone is huge as they can plant most perennials, herbs, trees, and vines. Some include;
- Herbaceous perennial edibles like asparagus, artichokes, rhubarb, strawberries, and prickly pear cactus
- Fruit trees like fig, cherry, apricot, apple, citrus trees, and nut trees
- Special trees like persimmons, pineapple guava, and pomegranates
- Almost every herb, for instance, thyme, oregano, rosemary, sage, and chives
- Plenty of flowering plants, with popular examples such as lantana, hibiscus, bird of paradise, and Indian hawthorn
9. USDA Zone 9
The temperature range for the zone is between 20- and 30-degrees Fahrenheit. Some common areas under this zone include California, Arizona, Louisiana, Florida, and East Texas.
This is an all-year-round planting zone. However, the accepted growing season length is nine months since the summer is too hot, which presents a considerable challenge for summer vegetable gardens. Vegetables that tolerate extreme heat are not suitable for this region. Some of them include;
- Bell pepper
- Pole green beans
- Some varieties of tomatoes
When buying plants for this region, look for ones that love heat and will thrive in the hot summers. Consider drought-tolerant varieties as well. Examples are;
- Sweet peppers
- Sweet potatoes
- Chinese red beans
Other plants to consider are;
- Citrus trees
- Many tropical fruits such as kiwi, passion fruit, guava
- Some specific types of apple, fig, apricot, and plum trees
10. USDA Zone 10
The areas here experience higher than average all-year temperature, with ranges between 30- and 40-degrees Fahrenheit. They include places like Central Florida, Arizona’s border with Mexico, and Southern California. It has the most extended growing zone in the United States, with mild winters and long summers.
Some of the plants you can grow here include;
- Snake plants
- Variety of palms and succulents
11. USDA Zone 11
This is on the other extreme end, with temperatures ranging between 40- and 50-degrees Fahrenheit. A few areas that are classified in this zone include Los Angeles, Miami, and San Diego. Gardeners in these areas should be conscious of the humidity levels as they go a long way in determining the plants they can have in their gardens.
Some plants that can survive here include;
- African lily plants
- Christmas Cactus
12. USDA Zone 12 and 13
The only areas in this zone across the United States of America are the Hawaiian Islands and Puerto Rico. Temperature ranges are between 50- and 70-degrees Fahrenheit. Plants that can do well here include;
- Amazon tree grape
- Bush beans
Answer: The USDA takes a lot of factors into account before publishing the hardiness zones. While our planet is getting warmer by the day due to various activities globally, the recent update in 2012 is derived from an extensive measurement and analysis period. It considers multiple aspects like the area’s proximity to a water body, elevation, and other microclimate effects.
However, planting zones should be used as a guide to help gardeners understand the conditions in an area and the best plants suited to those conditions. Relevant parties have used this guide for a long time, and notwithstanding any drastic activity or change, they are reliable and can help you make the right decisions.
Answer: It all depends on the conditions indoors. The growing zones give the temperature range for the coldest months in that region, and you can create an indoor environment that is more friendly to plants. As a result, growing zones predominantly apply to outdoor plants, as they are fully exposed to the natural conditions compared to the indoor ones.
Answer: Global warming is affecting planting zones, as seen from the variations in hardiness zones over the years. As human activities across the globe are continually driving temperatures up, the planting zones are shifting North as well. Looking at the baseline created between 1951 and 1980, the average temperatures between 1989 and 2018 are 3 degrees Fahrenheit warmer for most of the stations. There has been an increase in over 95% of the 244 stations checked. This shift is affecting gardeners since many species have disappeared in areas where they were native to. As a result, new species are coming up and the vegetation mix in these areas is being redefined, to adapt to the changing temperatures.
Answer: The world is divided into four climate zones and two of them have sub zones. The primary factors used to determine this classification include climate, vegetation, air pressure and temperature levels. The climate zones are arctic, temperate, tropical and sub-tropical. The areas under the arctic climate are the coldest with warmest temperatures never exceeding 10 degrees Celsius. The ground is frozen all year long here. Temperate regions are a bit warmer followed by the subtropical and eventually tropical.
If you are looking to create a fantastic garden, or start growing your own produce, do some due diligence. Plants depend on a myriad of factors for them to grow and thrive, and a good base to start from is determining your hardiness zone.
This information is readily available on the USDA website and will go a long way to shape the activities you to choose and take care of your plants. While at it, go an extra step and find out more about your area, for instance the wind levels, humidity and amount of rain. With all this information, you will be better poised to find a landscaping expert, prepare your garden and plant the right plants.