What Are Perennial Plants (And How To Care For Them)?

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Summary

Perennial plants are plants that come back every year. This makes them different from annuals, which only live for one growing year. 

Caring for perennial plants means doing it long-term as a result. You’ll need to consider how to best plant them, practice good soil care, watering, pruning, fertilizing, providing them with plant supports, and preparing them for winter.


What Are Perennial Plants?

A group of blazing star flowers outside.

Perennial plants (perennials) come back every year after winter. Perennial plants are unlike annual plants, which die over the winter, and biennial plants, which only live for two years

Of course, just because these plants are different don’t mean one is better than the other. They’re all good in different ways, depending on your situation.

During the winter, some perennials go dormant (shut down non-vital functions and remain passive until spring) and shed their leaves. This includes such plants as sage, coneflowers, and oaks, while others keep their leaves, such as pines and spruces. 

Perennials can have woody stems, such as trees and shrubs, or they can have non-woody stems, such as phlox or daylilies. Typically, though, perennials refer to non-woody plants.

How To Identify A Perennial Plant

It’s challenging to tell a perennial plant apart from other types of plants. There are a few ways to tell if a plant is perennial, though.

One way is if the plant grows in the spring after the winter. If it doesn’t, it’s an annual plant (annual).

Another is to read information about the plant, including labels in stores. 

Perennials also have shorter flowering periods than annuals.

Are Trees And Shrubs Perennial?

It is technically true that shrubs and trees are perennials. However, individuals in the gardening and horticulture fields refer to perennial plants as surviving the winter and lacking woody tissues (like trees and shrubs have). 

Trees and shrubs survive the winter regardless, so calling them perennials is unnecessary. However, plants that aren’t trees and shrubs don’t always survive the winter. So, it’s essential to categorize these plants as ones that do (perennials) and ones that don’t (annuals).

How To Care For Your Perennial Plants

Groups of black-eyed Susans outside.

Planting

The best planting time for most perennials is in April or May (you can plant trees and shrubs as early as March). Dig a hole in your soil at the same depth as the plant’s container and a bit wider. You will remove the container and plant inside the spot, gently cover it, and press the soil around your plant softly (using gloves). 

Water the plant with roughly the same amount as their container’s size.

Gardeners debate whether or not to cut a plant’s roots before placing it in the hole. Both methods have shown success.

 If you notice many roots outside the pot, trim them until they’re back inside the pot. However, if the roots are barely visible, it is best to leave them intact.

Soil Care

Perennials need a mix of sand, clay, and silt soil known as loam or loamy soil. This soil suits flower beds with perennials, annuals, biennials, trees, and shrubs. Loam has organic matter that gives nutrients to many plants.

You can find triple-mix soil in most garden centers, which combines loam, animal manure, and peat moss, ideal for plants requiring richer soils to thrive. Consider profiling your soil before you buy more. 

Silt and sand differ in size. Silt is a smoother variant of sand and appears in light grey to light brown shades. They are round or semi-round and may feel soft and difficult to manage when held in your hand.

Clay is very different from silt and sand. Clay particles are microscopical, dark, and flat. While you hold clay, it will remain together. Unlike sand and mud, clay has a characteristic smell, and you can shape it differently while applying hand pressure.

Once you know your soil, try to evaluate how much clay you have. If digging your holes takes a lot of time, you might have a dense clay layer. If that is the case, you can replace it with loam or find clay-friendly plants such as yarrow, black-eyed Susans, echinaceas, hostas, daylilies, or geraniums.

Watering

Remember to water your plants thoroughly after planting. Your plants will likely have different needs than others, so read their labels carefully to ensure you’re caring for them properly.

Pruning

It is common to need to cut most perennials back in winter or spring. While some dead leaves may remain, removing them can improve the plant’s appearance and free up space for growth. 

You need to cut most plants just a few inches above the ground. For other plants, the leaves come off as the first frost or snow falls in November, such as hostas. Other plants, such as lavender, are better to prune after winter.

Additional pruning may also be necessary as the plant grows throughout the year. However, I advise against pruning perennials in their first year of planting. It’s best to wait until the second year when the plant is more established (at a stage where it needs less care from you).

Deadheading may be necessary for some perennials to produce multiple flowering periods. 

Fertilizing

Some perennials might need an extra hand to develop their flowers, roots, or leaves. Compost is a great way to do this. 

I like to add slow-release fertilizer (4-3-7) to my house and garden plants. These are generic and mild fertilizers that help the plant’s overall health and flower development, especially fruit production for tomato vines or even blueberry bushes.

May to September is an excellent period to add fertilizer to your plants.

Most gardeners prefer to use phosphorus-based fertilizer (the second ingredient higher in the NPK formula) when they plant perennials. Phosphorous (P) assists plants to create and fortify root systems so the plants have better roots and absorb more nutrients from the soil.

Nitrogen (N)  fertilizers (the first number, the highest in the NPK formula) are for plants that look yellow or have difficulty growing. 

Limit using this fertilizer for older plants.

I recommend fertilizing your plant with potassium above the other ingredients because it is a generic and sustainable way to keep your garden and the natural ecosystems healthier. There are other organic fertilizers (fertilizers with natural byproducts) at your disposal that will make your plants happy and will not endanger nearby species or water bodies. 

Providing Plant Supports

Plants may require support, such as bamboo sticks or rope, to promote steady growth. You can provide gentle support using bamboo sticks, rubber bands, or soft strings. 

Preparing For Winter

Cutting back perennial plants is crucial during the fall season. Remove all dead material from the base of the plant. This process is necessary as most perennials experience dormancy due to leaf loss or tissue death. It is a natural process in many plants, leaving only the roots and base of the perennials in the ground.

For healthy plants, prune seasonally. Trim daylilies and hostas in November and lavender and ornamental grasses in April. 

Use mulch, not leaves, to cover plants during colder months to prevent disease and fungal growth.

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