Perennials

A perennial is any herbaceous plant that lives for more than two years. Often, they die back in the winter and grow again the following spring. A few plants are considered perennials because they readily come back from seed, though they aren’t true perennials.

Perennials are often grown for aesthetics, and can provide countless services, such as controlling water run-off, preventing soil erosion, and providing habitat or food for wildlife. Perennials are so versatile, and with a wide variety to choose from, there’s usually one for almost any kind of space. Choosing a perennial doesn’t have to be complicated, but it takes some observation and planning to help ensure the plant will survive and thrive. It’s most important to consider the conditions of the area in which you’re planting. Once you’ve narrowed down your selection, then you can choose by which plant will fit your needs.

Click here to view some of the perennials available at America’s Best Flowers.

Hardiness

Hardiness reflects a plant’s ability to survive the low temperatures of winter. Each area has a number that represents the hardiness zone, which serves as a guideline for which plants will likely grow there. The hardiness zone for Madison and surrounding areas is 4b, though sometimes the unique features of a particular area can create a microclimate able to support plants considered 5a.

Some plants are less hardy than others, and we do our best to carry perennials that are successful in the Madison and surrounding areas. It’s helpful to note the hardiness of each plant before purchasing and note what works best in your area.

Steps for Selecting Perennials:

Determine Soil Type

Rub a small amount of moist soil between your thumb and fingers to feel its texture. A clay soil will be slick and smooth, whereas a sandy soil will be gritty and crumbly. A loam soil will be intermediate, feeling somewhat gritty, yet sticks together easily.

Determine Soil Moisture

The amount of moisture a soil contains varies based on the soil type and the soil’s proximity to the groundwater level. Moist soils are relatively close to groundwater levels, and dry and medium soils are relatively far from them. Moist soils can be any soil type that holds water continuously throughout the growing season. Dry soils, including sandy soil or soil that incorporate gravel, drain easily and rarely accumulate standing water even after a heavy rain. Medium or mesic soils, including clay and loam, may accumulate standing water and retain it for one to three days following a heavy depending on the amount and intensity of the rainfall.

Determine Exposure

Perennials have different light requirements making them suitable for different areas. Observe the area over time to see how much light it gets, how long it gets light, and when. Generally speaking, full sun perennials need at least 6 hours of direct sun per day, and shade perennials need less than 6 hours of direct sun per day. Afternoon sun (or a Southern or Western exposure) tends to be more intense, while morning or late afternoon sun (or a Northern or Eastern exposure) tends to be less intense.

Desired Height and Width of Plant

Determine the size you would like or what your space will allow when the plant is mature. There’s a perennial of every size; some stay low to the ground and spread, while others grow tall and narrow, with everything in between.

Blooming Period

There is no perennial that blooms all summer long. Each perennial has its own bloom period that usually lasts for about 2-4 weeks. In order to have blooms all summer, include plants that have different bloom periods to cover each time of the season.

Planting

Prepare garden bed by removing existing vegetation. Till the soil 12 inches deep and mix in compost. Dig a hole 2x the width of the root ball and the same depth as it is in the container. Loosen the roots a bit, and score and tease roots that encircle the root ball. Mulch 1-2 inches with light organic compost.

Care

Water well after planting and as needed for the first few weeks. Once established, most perennials generally require 1” of moisture per week, so they should only need watering in times of drought.

Perennials generally don’t need much fertilizer, but a dose of granular fertilizer each spring is helpful. Deadhead (remove spent flowers) regularly. Watch for signs of pest or disease throughout the growing season. Catching issues early will give you a better chance of successful treatment.

Many gardeners prune spring and summer blooming perennials in the fall after a killing frost. Another great approach is to leave them over winter and clean up in the spring. Many flower heads make great bird food and stems provide winter interest in a snowy landscape.

Mulch with straw or chopped leaves 2-4 inches deep after several hard frosts, when the ground is frozen. Uncover in early spring once the ground begins to thaw.

Perennial Lists

Perennials by Bloom Period

Perennials for Borders

Perennials for Shade or Part Shade

Perennials for Moist Soil

Perennials for Attracting Birds and Butterflies

Rabbit-Resistant Perennials

Deer-Resistant Perennials

Perennial Cross Reference Index