6 Questions That Will Help You Pick the Best Plants for Your Site
Before you head to the nursery, learn more about your outdoor space
One of the most common questions gardeners have when planting a new space is, “What is the best thing to plant here?” While maintenance and design are important considerations, the existing site conditions are key to answering that question. Before you begin your plant search, take time to learn more about your yard, from its soil type and sun exposure to the region’s climate zone and rainfall pattern. This information will help you determine which plants will be best-suited to your site.
A sloped woodland garden in Maine features highbush blueberry (on the left) and lowbush blueberry (on the right), along with ferns and other woodland natives.
2. What part of the country is it in? This is a broader-brush approach than the climate zones but also easier to identify. It is an especially important question if you want to use native plant species. Northeast, Southeast, Southern Plains, Midwest, Northwest, Southwest and Pacific Coast — each of these areas has its own characteristics of soils and climate that may favor some species over others.
2. What part of the country is it in? This is a broader-brush approach than the climate zones but also easier to identify. It is an especially important question if you want to use native plant species. Northeast, Southeast, Southern Plains, Midwest, Northwest, Southwest and Pacific Coast — each of these areas has its own characteristics of soils and climate that may favor some species over others.
Clay soil is dense and sticky when wet. It can hold a lot of water but becomes hard when dry.
3. What is the soil like? It’s important to know your soil type and moisture level, which will help ensure you put the right plant in the right place. Is the soil wet, dry or somewhere in between? Is the area prone to flooding, or is it well-drained?
An easy soil test can help you determine your soil’s type. Is the texture clay-like, sandy or a nice loam, easily broken up but with enough structure to hold together?
Less obvious is soil pH, which is a measure of the soil’s acidity. Soil acidity may not be as big an issue for annuals and perennials, but if you are planting trees and shrubs, it is worthwhile to confirm that the soil chemistry is compatible with these long-term investments. There are DIY tests for soil pH, but sending a sample to a soil laboratory is a more reliable way to get a number you can count on. You can do treatments to change soil pH, but this will require long-term monitoring and annual re-treatments to effect a change.
3. What is the soil like? It’s important to know your soil type and moisture level, which will help ensure you put the right plant in the right place. Is the soil wet, dry or somewhere in between? Is the area prone to flooding, or is it well-drained?
An easy soil test can help you determine your soil’s type. Is the texture clay-like, sandy or a nice loam, easily broken up but with enough structure to hold together?
Less obvious is soil pH, which is a measure of the soil’s acidity. Soil acidity may not be as big an issue for annuals and perennials, but if you are planting trees and shrubs, it is worthwhile to confirm that the soil chemistry is compatible with these long-term investments. There are DIY tests for soil pH, but sending a sample to a soil laboratory is a more reliable way to get a number you can count on. You can do treatments to change soil pH, but this will require long-term monitoring and annual re-treatments to effect a change.
Native and other drought-tolerant plants have low-water needs in this Palos Verdes, California, yard.
4. How much water does it get? Does your climate get regular rain throughout the growing season, like the Northeast? Or are you in an area with dry summers, like Southern California?
By selecting plants adapted to your climate and rainfall patterns, particularly regionally native species, you can avoid supplemental watering. Otherwise you must be willing to add supplemental water, or invest in an irrigation system, for when it’s too dry.
4. How much water does it get? Does your climate get regular rain throughout the growing season, like the Northeast? Or are you in an area with dry summers, like Southern California?
By selecting plants adapted to your climate and rainfall patterns, particularly regionally native species, you can avoid supplemental watering. Otherwise you must be willing to add supplemental water, or invest in an irrigation system, for when it’s too dry.
This open landscape in Vermont gets full sun and is well-suited for many flowering perennials.
5. What’s the sun exposure? Plants thrive when they are sited in a spot that receives the sunlight they prefer. While it’s possible to change some of your site conditions to meet the needs of a new plant, it is generally easier and more sustainable to find plants that are adapted to existing conditions.
At the nursery, you will likely see one of the following terms on each plant’s label, indicating how much sun exposure it prefers.
5. What’s the sun exposure? Plants thrive when they are sited in a spot that receives the sunlight they prefer. While it’s possible to change some of your site conditions to meet the needs of a new plant, it is generally easier and more sustainable to find plants that are adapted to existing conditions.
At the nursery, you will likely see one of the following terms on each plant’s label, indicating how much sun exposure it prefers.
- “Full sun” plants want six or more hours of direct sunlight.
- “Partial sun” means two to five hours of sun exposure, either continuously or scattered over the course of the day. “Partial sun” and “partial shade” are pretty similar, with partial shade implying a little less sun.
- “Shade” means two hours or less of direct sun exposure. There are several degrees of shade. High shade, filtered shade or open shade refer to situations where there is little direct exposure to the sun but there is a fair amount of indirect or reflected light. This may exist under a high canopy of trees or on the north side of a building. Dense or heavy shade is found under a low or thick canopy of evergreens, or under trees or shrubs with very large leaves. Not surprisingly, there are many fewer species that will do well in dense shade than in open shade.
These arborvitae (Thuja occidentalis ‘DeGroot’s Spire’) will mature to be 20 to 30 feet tall and 5 to 6 feet wide, staying in scale with the house and not blocking the window.
6. How big is the site? It’s important to know how much room you have to plant, so that you can select a plant species that won’t outgrow the space. For example, planting a big tree too close to a building can result in structural damage to the building and eventual loss of the tree. Foundation shrubs that are too large for a site may look great for a couple of years but may outgrow their locations, blocking windows or walkways.
Next steps. Once you have your site information in hand, you are ready to do your plant search. Learn more about selecting the right plants in an upcoming article.
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6. How big is the site? It’s important to know how much room you have to plant, so that you can select a plant species that won’t outgrow the space. For example, planting a big tree too close to a building can result in structural damage to the building and eventual loss of the tree. Foundation shrubs that are too large for a site may look great for a couple of years but may outgrow their locations, blocking windows or walkways.
Next steps. Once you have your site information in hand, you are ready to do your plant search. Learn more about selecting the right plants in an upcoming article.
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1. What climate zone is it in? The USDA has a zone map that breaks the U.S. into 13 zones based on how cold each zone gets, on average, in winter. (Each zone is separated by 10 degrees Fahrenheit.) Most garden plants have been evaluated for their USDA cold hardiness, with those that require a period of cold in winter also sometimes having an upper limit to their cold-hardiness range.
Sunset Climate Zones, developed by Sunset Magazine, take more complicated climate effects — like summer drought, rainfall patterns and extended hot or cold spells, as well as other geographical factors — into account for a map that divides the U.S. into 45 climate zones. The number of zones in a given state varies widely. Florida, for example, which is relatively flat and surrounded by water, has three zones. California, with a much more diverse topography, has 24 zones.
Additionally, a newer climate map developed by the American Horticultural Society breaks the U.S. into zones by the average number of days each year the temperature exceeds 86 degrees Fahrenheit. This is a measure of heat stress on a plant. While a plant can be killed outright by exposure to excessive cold, the effects of heat stress are slower-acting, affecting blooming, fruit production, photosynthesis and more, effectively weakening the plant over time. Currently, not all garden and landscape plants have this extra information.
Tip: You can create microclimates in your garden to slightly affect the existing climate zone. For example, using mulch or planting wind screens may create a warmer area, while gardening in a shaded site may lower the summer temperatures a bit to reduce heat stress.