University of Illinois Extension
Introduction to Perennial Garden Design - Stepping Stones to Perennial Garden Design - University of Illinois Extension

Introduction to Perennial Garden Design

Like the musician, the painter, the poet, and the rest, the true lover of flowers is born, not made. And he is born to happiness in this vale of tears, to a certain amount of the purest joy that earth can give her children, joy that is tranquil, innocent, uplifting, unfailing. Given a little patch of ground, with time to take care of it, with tools to work it and seeds to plant in it, he has all he needs.
-- Celia Thaxter (1835-1894)

Perennials have long been popular with gardeners. They are relatively easy to grow and offer a wide variety of colors, forms and textures. A perennial is a plant that does not keep a woody skeleton above ground all year. They die to the ground, re-emerging in the spring from an underground storage structure.

The history of perennial gardens dates back to 1890. George Nicholson, curator for the Royal Botanic Gardens at Kew, England, suggested a perennial-only garden, steering the gardeners of the time away from the regimented garden styles that relied primarily on bedding plants. Since then the history of perennial use has introduced the border garden, the island garden and the mixed garden.

Originally border perennial gardens were set against a backdrop of a hedge. Perennials were grouped together and tiered with the tallest in the back and the shorter in the front. The purpose was to separate the lawn area from the border. Perennial borders in this form had disadvantages. They required a great deal of space and could only be viewed from one side. The background competed for light, shading the gardens at times causing the tall plants to lean forward and slowing air circulation. Island beds were introduced in the 1950's. These beds were set in the lawn area and could be viewed from all sides. The shading and air competition problems were eliminated. Taller specimens were placed in the center of the bed. As a rule, their height was usually no more than half the width of the bed.

Today, space limits garden ideas for the average homeowner. It is difficult to devote an entire area to only one type of plant material such as perennials. Mixed borders are popular. Annuals or bedding plants offer color all season and woody ornamental plants (shrubs and trees) offer structure and framework. This series will focus on perennials only. However, there will be many instances where incorporating annuals for continuous color, or a landscape shrub for winter effect, will enhance your garden. Follow the basic steps presented. Once you have determined your gardening goals, assessed your site, determined garden areas, determined your gardening style, selected perennial plants and drawn up your garden, adding these other plants will be easy.

Photos of mentioned plantsThe term perennial commonly means hardy herbaceous ornamental plant. That is, they are plants whose top portion dies to the ground every year, surviving the winter to re-emerge the following spring from an underground storage structure, generally living for three or more years. They offer seasonal interest with specific blooming periods. The term perennial does not mean perpetual for there are short-lived perennials and those that last almost indefinitely. For example, peony (Paeonia), daylily (Hemorocallis) and hosta are extremely long-lived, while shasta daisy (Leucanthemum), flax (Linum) and Maltese Cross (Lychnis) have proven to be short lived, lasting only two or three years. For this reason, there is a common misconception about perennials. Many gardeners want gardens that only have to be planted once and afterwards return every year with a glorious spectacle! Yes, there are low maintenance perennials. You can plant them and expect relatively lower amounts of required upkeep. Will they return every year to offer the glorious spectacle you want? No. Keep this in mind as you work through this series.

Why design at all? Why not just plant a bunch of perennials and see what happens? Well, this can be done, but often the result is chaos and an unhappy gardener. Designing a flower garden and seeing it develop before your eyes can be rewarding. It takes time, knowledge and experience to prepare a good one. The planning stage is too often overlooked by the impatient gardener resulting in a haphazard collection of plant materials. The eye needs a sense of order. Too many variations in sizes, shapes, colors, and textures create confusion. Remember, the most spectacular gardens all begin with a carefully thought-out design.

There are many perennials available to plant in your garden. Perennials bloom throughout the season but at different times. There are spring bloomers, summer bloomers and fall bloomers. The ultimate goal of a perennial garden is a personally pleasing flow of plant material from season to season. This flow can consist of flower color, foliage color, plant texture, plant shape, plant size or any other desirable ornamental feature. Note 'desirable' - personal taste comes into effect and what is desirable to one gardener may be an eyesore to another! To some the bleached winter foliage of Miscanthus is desirable, while others cut it down in late fall. Our goal is to help you achieve this pleasing succession of plant characteristics. By following the guidelines, your perennial garden will delight you with seasonal beauty year after year.

Many gardeners want a recipe to follow when it comes to designing a perennial garden, and for that matter, for general gardening. They yearn for a step-by-step process that explains what to do and when to do it, insuring success. As with many cooking recipes, variations exist. Everyone has a favorite chocolate cake recipe that may differ from others in regards to specific ingredients or sequence. But the result is the same - a delicious chocolate cake! Thus it is with gardening. This can be a frustrating process for those looking for exact directions. Ask one gardener how they prepare their garden bed and then compare this to another gardener's bed-preparation procedure. The steps may be different, but the results are the same - a beautiful garden. Every garden location is different and therefore, every garden is different! There are very few rules or definites when it comes to working with perennials. Remember this as you progress through this series.

Gardening, Laws of: (1) Other people's tools work only in other people's gardens. (2) Fancy gadgets don't work. (3) If nobody uses it, there's a reason. (4) You get the most of what you need the least.
- From The Official Rules

Seriously, there are a few rules upon which most gardeners will agree:

A Perennial Garden Is Never Finished!

A garden evolves and matures. Some plants are short-lived while others are passed down through generations of gardeners. So, certain areas in your garden change every few years as you replace a short-lived plant, while other plants may take years to achieve the desired quality for which they were chosen. In the meantime, your tastes will change as you are introduced to new plants and combinations by fellow gardeners. Accept and embrace these changes. Your gardening skills grow and mature along with your plants. Every year something new will appear, either planned or by accident - this is the joy of gardening!

Photos of mentioned plants

Perennials Are Movable

Unlike larger woody ornamental landscape plants, perennials can be moved relatively easily - they are not set in concrete! In fact, ask any gardener about moving perennials around throughout the growing season and you will find this is normal! It seems we are forever searching for the perfect location. Now there are a few exceptions, such as False Indigo (Baptisia australis) and Gas Plant (Dictamnus albus), that do better if left undisturbed for many years; however, the majority of perennials can be moved and do better with scheduled dividing... but more on this later in Bed Preparation and Maintenance.

Tall Plants in the Back and Short Plants in the Front.

Even this obvious declaration has exceptions! Coral bells (Heuchera sp.) offer a 6-10 inch basal clump of foliage, ideal for the front of the garden. However, in bloom it can reach 2 feet tall, making it ideal for the mid-section. When in bloom, coral bells are semi-transparent, that is the blooms don't block out what is behind it, so when placed in the front, you can still see through the flowers. When placed mid-border the flowers appear to float above the plants in the front border. The majority of the time tall, dense plants such as a six-foot plus ornamental grass should be placed in the back of the border or the center of an island bed.

Design According to the Tastes of the Gardener

Who are you designing this garden for? If for yourself, let your own personal tastes dictate your choices. You can give 20 different people the same 20 perennials and they will arrange them differently according to their preferences, interests and experiences. If you want an all chartreuse garden then set that as a goal and start planning - it's your garden!