What Are Perennials? Garden Plants That Return Every Year

The fascination of perennials begins right here: plants that return year after year without needing to be planted again each time. But what exactly qualifies as a perennial, how does it differ from an annual plant – and why do some supposed “repeat bloomers” fail to come back after all?

What perennials really are – and what they are not

In the broadest sense, any plant that lives for more than two years is perennial. That definition would include every tree and shrub. In the usual home-garden sense, however, a “perennial” means something more specific.

In everyday gardening, perennials are plants whose above-ground parts die back in autumn and which send up new growth from their roots, tubers or rhizomes in spring.

Common examples include hostas, delphiniums, daylilies, coneflowers and peonies. You will usually see no sign of them in winter: beneath the soil, they are waiting for spring to begin.

Annual, biennial, perennial – the life cycle matters

To classify perennials properly, it helps to consider the three main types of garden plant:

• Annual plants (annuals): They germinate, grow, flower, set seed and die within one growing season. Examples include pot marigolds, zinnias and basil.
• Biennial plants (biennials): They mainly produce leaves in their first year, generally flower in their second year, then die. Examples include foxgloves and hollyhocks.
• Perennial plants (perennials in the wider sense): They survive for several years and often flower repeatedly.

Garden practice makes this less straightforward. Many gardeners grow certain perennial species as annuals because their appearance declines or because they are sensitive to frost.

Woody or herbaceous – a key distinction

Whether a plant is woody or not is central to deciding whether it is a perennial.

Over time, trees and shrubs develop layers of dead, lignified tissue: the material we know as wood. Only the youngest layers beneath the bark carry water and nutrients. As producing wood requires a plant to survive for several years, the following applies:

Every woody plant is perennial – but not every perennial plant is woody.

This also includes very small woody plants. Blueberries and some dwarf shrubs grow to only a few centimetres tall and can look much like perennials, but botanically they are woody plants.

Traditional garden perennials, by contrast, are herbaceous: their shoots do not become permanently woody. In autumn, they usually die back to just above ground level, while their underground parts survive.

Non-woody perennials: hidden energy beneath the soil

Many of the most popular garden plants belong to this group. They die back in autumn, but first build energy reserves in roots, tubers or bulbs. These reserves fuel their new growth in spring.

Bulbs, tubers and rhizomes – remarkable little stores

Understanding how perennials store their energy makes them easier to identify, particularly when there is still nothing visible above ground.

• Bulbs: Layered storage organs, as found in tulips, daffodils and ornamental alliums. They retain nutrients for growth in the following year.
• Tubers: Thickened root or stem sections, for example in dahlias and potatoes.
• Rhizomes: Underground runners, such as those of irises and many grasses.

Where there is a substantial bulb, tuber or rhizome, there is almost always a perennial plant behind it.

Annual species, on the other hand, invest primarily in seed, since they must secure their species within a single season. Elaborate storage organs offer them no benefit.

Garden grasses: a lawn rather than a throwaway product

Grasses can be annual or perennial. Ornamental lawns and most decorative gardens rely mainly on perennial varieties – a lawn that disappeared after one year would be a nightmare for most homeowners.

Some native prairie grasses, such as switchgrass and Mexican feather grass, are typical perennial species that gradually form dense clumps. Many ornamental grasses can remain in the border throughout the year, with their dry stems lending structure to the winter garden.

When “perennials” do not return – the most common misconceptions

Garden forums are full of questions such as, “My tulips have disappeared – weren’t they perennial?” The answer is often more complicated than expected.

Tulips in particular are often sold as perennials, but in the garden they tend to behave more like annuals. Many modern varieties use so much energy in their first year to produce large, spectacular flowers that hardly any reserves remain for strong flowering in the second year.

Anyone wanting to keep tulips for many years needs free-draining soil, sparing watering after flowering and plenty of resting time.

Pansies are another classic example. Botanically, they are perennial, yet in their second year they usually look less appealing, flower less freely and become partly woody. Most gardeners therefore treat them as annuals and replace them regularly.

Hidden perennials: naturally long-lived, but grown as annuals in the garden

Several familiar food crops surprise many amateur gardeners: they are perennial in their native habitat, but are usually cultivated here for just one season.

• Tomatoes: In their tropical place of origin, they are perennial plants, but they cannot survive winter outdoors in Central Europe.
• Sweet peppers and chillies: These are perennial too and can be grown on in winter quarters.
• Potatoes: They produce tubers from which they could grow again, but in agriculture they are replanted every year.

In a greenhouse or indoors, keen gardeners can genuinely keep tomato plants for several years. Yields often decline over time, but the plants can continue producing fruit for a long while.

“Volunteer” plants: garden stalwarts or simply chance arrivals?

Anyone who has gardened for a while will know them: a tomato suddenly appears among the carrots, or a sunflower pops up in the middle of a border. These plants grow from seeds that fell into the soil the previous year and germinate when conditions are favourable.

Such “volunteers” can look like perennials, but they are actually new plants grown from fresh seed.

Typical self-seeding plants include:

• Tomatoes
• Squash and courgettes
• Melons
• Beans
• Sunflowers

In the vegetable patch, this can be a welcome surprise – who would not enjoy a free extra tomato? In ornamental gardens, however, these visitors should be kept under control, otherwise they may crowd out planned planting.

Practical guide: how to recognise perennials in your own garden

People new to gardening often stand puzzled before bare borders in spring. A few rules of thumb can help with identification:

• Mark their positions in autumn: Use small sticks to show where perennials are growing if their foliage dies back completely.
• Check the texture: If a shoot feels woody, it is more likely to belong to a shrub or subshrub, such as lavender or rosemary.
• Look below ground: If careful digging reveals bulbs, tubers or thick root sections, that strongly suggests a perennial.
• Keep plant labels: Rather than throwing away labels from the garden centre, collect them to maintain an overview.

One useful tip for impatient gardeners: many perennials start late. Coneflowers, cranesbills and some grasses in particular can take their time before producing new shoots. Removing them too early in a moment of “panic” often means losing well-established plants.

Getting more from perennials: medicinal plants and lasting flavours

Many so-called “herbs” are actually perennial plants or subshrubs. Position them well once, and you can enjoy them for years.

• Echinacea (coneflower): Popular as a medicinal plant and a magnet for bees.
• Yarrow: A hardy wild perennial with versatile uses as a tea and cut flower.
• Mint: A vigorous perennial that will readily take over an entire bed unless it is contained regularly.

Mint demonstrates particularly well how vigorous perennials can be: planted directly in a bed, it soon forms a proper carpet. A large pot or a buried root barrier is the better option.

For newcomers, a mixture of tough, dependable perennials – for example daylilies, lady’s mantle and purple coneflower – together with a few more experimental species is worthwhile. Over the years, not only will the bed grow, but so too will your knowledge of the garden’s quiet long-term residents.