Herbaceous perennials are plants that live for more than one year but are not a woody plant such as a tree or shrub. Perennials grow and flower during the spring, summer, or early fall and then die back to the ground during the winter. Although they may produce seeds, these plants rely on vegetative reproduction unlike annuals which reproduce primarily by seed. The different forms of vegetative reproduction structures include bulbs, rhizomes, tubers, and woody crowns. Perennials are better-suited to surviving in colder climates such as Connecticut which ranges from USDA zones 7b to 5b. The larger root systems of perennials allow it to access water and nutrients that may be deeper in the soil making them more drought-tolerant than shallow-rooted annuals may be. Another benefit to perennials is that they will grow for many years with minimal care and do not need to be replaced every spring as annuals do.
Site Selection
Site selection is an important consideration when choosing perennials. While some perennials may adapt to less than perfect sun or shade availability, they may not bloom as abundantly or vibrantly in light conditions that are not optimum for the species. Before any planting, a soil test will determine any soil amendments that may be needed and will also give fertilizer recommendations. It may be best to select species for the soil conditions that are present rather than to amend soils for a particular plant.
Water Requirements
Regular watering is essential. As with most plants, perennials require about an inch of water at least once a week to keep plants looking good and producing more blossoms. Even drought tolerant species need water to get established and also during long dry spells. Check to see that plants are getting adequate water by either digging down after watering to see how deep the water has penetrated or set out a container and water until the one inch of water is collected. Avoid overwatering established perennials to promote deeper rooting.
Mulching your perennial plantings will keep weeds down and also decrease evaporation as soil under mulched plants will stay moist longer. Any organic material can serve as a mulch but fine-textured shredded bark, cocoa bean hulls or buckwheat hulls may be more in keeping with the scale of smaller annuals. Usually only an inch or so of mulch is necessary around perennials. See Mulch Basics for additional information.
Fertilizer Requirements
In general, fertilizers formulated for flowering plants would contain amounts of nitrogen less than or equal to the amounts of phosphorus (i.e. 10-10-10 or 5-10-5). This is because phosphorus encourages flowering. Too much nitrogen will stimulate green leafy growth at the expense of flower production. Also, the recommendations are made for granular fertilizer formulations. These will generally supply nutrients to the plants for about 6 to 8 weeks. During periods of excessive rainfall or frequent irrigation, the nutrients may be leached out of the soil and fertilizer may need to be reapplied. See Suggested Fertilizer Practices for Flowering Plants for additional information.
Early-season Perennial Suggestions
| Variety | Bloom Time | Height | Sun or Shade | Comments |
| Allium, Allium | Late spring | 12" to 60" | Full sun | Large globe-like blooms in shades of purple, pink, and blue that can be up 10" wide. |
| Ajuga reptans, Bugleweed | May to June | 6" to 9" | Full sun to part shade | Will grow in full shade but best foliage color will be in part-sun. |
| Anemone sylvestris, Snowdrop anemone | Late spring to summer | 12" to 18" | Full shade or filtered sun. | White flowers with yellow centers, blue-green foliage. Naturalizes easily. |
| Aquilega, Columbine | April to May | 18" to 24" | Full sun to part shade | Spurred flowers that are attractive to pollinators and hummingbirds. Susceptible to leafminers. |
| Arabis caucasica, Garden rockcress | April to May | 6" to 12" | Full sun | White blooms that tolerate gritty but well-drained soils. |
| Aurinia saxatilis, Basket of gold | April to May | 6" to 12" | Full sun | A low-growing, spreading perennial that is very attractive in rock gardens. |
| Bergenia sp., Saxifrage | Spring | 12" | Full sun to part shade | Glossy dark green leaves that turns reddish-bronze, pale pink to ruby red blooms. |
| Brunnera macrophylla, Siberian bugloss | Spring | 12" to 18" | Dry shade | Sky-blue, forget-me-not-like flowers mix well with daffodils. Self-seeder that spreads. |
| Caltha palustris, Marsh marigold, Cowslip | April. May | 12" to 24" | Part shade, shade | Yellow blooms. Prefers boggy areas so plant by a pond, stream, or marsh. |
| Convallaria majalis, Lily of the Valley | Spring to early summer | 4" to 8" | Part shade | Nodding stems covered with tiny, white, bell-shaped flowers. Can spread to many areas. |
| Crocus, Crocus | March to April | 6" | Full sun to part shade | Purple, white, or yellow blooms that will naturalize. |
| Dicentra, Bleeding Heart | Early to late spring | up to 36" | Full to partial shade | An old-fashioned perennial with dangling heart-shaped flowers. |
| Disporum flavum, Fairy bells, Solomon's seal | Mid to late spring | 30" | Part shade, shade | Short-lived, nodding yellow flowers. |
| Doronicum, Leopard's bane | Mid-spring to early summer | 12" to 18" | Full sun to part shade. | Bright yellow daisy-like flowers and heart-shaped foliage. Pairs well with tulips. |
| Epimedium, Epimedium, Fairy wing's, Bishop's hat | April | 12" to 24" | Light shade | Long-lived, shade tolerant groundcover, foliage often evergreen. Blooms in pink, white, yellow, and reddish-rose. |
| Galanthus, Snowdrop | Mid-March | 3" to 6" | Full sun to part shade | So named because it may actually bloom with white, bell-shaped flowers through a cover of snow. |
| Helleborus sp., Lenten rose | Mid-March to April | 12" | Part sun to light shade | Rose-like blossoms in shades of pink to maroon. Glossy evergreen leaves that turn bronze in the winter. |
| Hyacinthus, Hyacinth | Early spring | 10" | Full sun | White, pink, red, pale yellow, and purple very fragrant blooms. |
| Iris sp., Bearded Iris (Miniature Dwarf, Standard Dwarf, Arils, Spuris) | Early to late spring | Varied | Full sun | Many varieties in shades from white to deep purple-black. Grow from rhizomes in well-drained soils. |
| Lupinus, Lupine | Late spring | 12" to 48" | Full sun | Tall, spiky racemes of sweet pea-like flowers in shades of pink, yellow, salmon, blue, and purple. |
| Muscari, Grape hyacinth | Mid-spring | 6" to 9" | Full sun | Deep purple-blue upright stalks of dense bell-like blooms. Will naturalize. |
| Myosotis scorpioides, Forget-me-not | May to October | to 24" | Shade | 5-petaled petite blue blooms that grow well near streams and brooks. |
| Narcissi, Daffodil | Late-march to mid-June | 12" to 18" | Full sun | Long-lived blooms in combinations of white, yellow, salmon, orange, and pink. Will naturalize. |
| Papaver orientalis, Oriental poppy | Late spring | up to 36" | Full sun | Delicate, crepe-paper like blooms that can be up to 6" across. |
| Peony sp. | Mid to late spring | 24" to 48" | Full sun | Bloom time may be extended up to 8 weeks by planting a variety of Peony species. |
| Phlox divaricata, Wild blue phlox | April to June | 12" | Part shade | Pale blue to lavender to violet blooms. |
| Primula polyantha, Primrose | Early spring through summer | 18" to 24" | Full sun to part shade | Wide variety of colors: white, cream, yellow, orange, red, and pink. Do not transplant well. |
| Pulmonaria, Lungwort | Early spring | 14" | Part to full shade | A woodland plant that prefers a shady or moist location. Blue, pink or white flowers. |
| Pulsatilla vulgaris, Pasque flower | April to May | 9" to 12" | Full shade or filtered sun. | Pale or dark violet flowers. Easy to raise from seed. |
| Sanguinaria canadensis L., Bloodroot | March and April | 6" to 9" | Part to full shade | Bloodroot likes to grow along the edge of a wood or stream. Solitary 2" wide white flower. |
| Tiarella cordifolia, Foamflower | May | 9" to 12" | Part to full shade | Easy to grow in moist soils. Pinkish buds open to tiny white flowers. |
| Trillium sp., Trillium | Late winter to early spring | 12" to 18" | Part shade | 3-petaled blooms in shades from white to purple. Plants grown from seed will not bloom for 7 to 9 years. |
| Viola odorata, Wild violets | Late winter to early spring | 6" to 8" | Part shade | Heart-shaped leaves with purple-blue flowers. Naturalize easily. |
Mid to Late-season Perennial Suggestions
| Variety | Bloom Time | Height | Sun or Shade | Comments |
| Acanthus, Bear's breeches | June to August | 36" to 48" | Full sun to part shade | White, pink or purple snapdragon-like flowers on spikes that rise above the foliage. |
| Achillea millefolium, Yarrow | June to September | 30" to 36" | Full sun | White to pink flowers in clusters of 15-40 tiny blooms in a single disc. Deadhead spent flowers to promote additional blooms. |
| Agastache foeniculum, Anise hyssop | Early summer to first frost | 24" to 48" | Full sun to part shade | Upright lavender to purple blooms that are great for pollinators. |
| Alcea, Hollyhock | June to August | 72" to 96" | Full sun | An old-fashioned garden favorite with white, pink, or red blooms growing on tall stems. |
| Anemone sp., Japanese anemones, Windflowers | Late summer, early fall | 24" to 34" | Full or part sun | Delicate masses of 2-3" blooms swaying on slender stems. 6 to 8 weeks of bloom time in shades of white, pink, or violet. |
| Asclepias, Milkweed | June to August | 12" to 30" | Full sun | The many varieties of milkweed provide blooms in white, yellow, pink, and orange that are not only attractive to pollinators but provide food for the caterpillar of the Monarch butterfly. |
| Aster, Aster | Summer to fall | 8" to 48" | Full to part sun | Daisy-like flowers ranging from white to pale pinks and blues to deep pinks and purples. Pinch back before July to control height and encourage bushiness. |
| Astilbe, False spirea | May to June | 18" to 24" | Part to full shade | Fern-like mounds with erect, feathery, plumed flower panicles in pale to dark pink. |
| Boltonia asteroides, False aster | Mid-summer to early fall | 48" to 60" | Full sun to part shade | Clouds of white, yellow, or pink aster-like blooms. Cut back by 1/3 in May and again in July for denser blooms. |
| Campanula, Bellflower | June to July | 36" | Full sun | Upturned, open cup-shaped blooms purple-blue, pink, or white. |
| Chelone, Turtlehead | July to September | 24" to 48" | Full sun to part shade | White to pink flowers, grow in dense spikes. Grows in moist to wet soils. |
| Chrysanthemum, Mums | Late July through October | up to 18" | Full sun | Pinch back new shoots to 2-3 leaves when 6" tall, pinch back again when 12" prior to mid-July to encourage fuller plants. Divide plants every 3-4 years. |
| Chrysopsis, Golden asters | Late summer through fall | 18' to 36" | Full sun | Bright yellow flowers open in late summer and continue through fall. The grey-green leaves are curiously twisted. |
| Coreopsis, Tickseed | Early summer to fall | 12" to 24" | Full sun, some afternoon shade. | Gold, yellow, orange, or red flowers bloom on wiry stems with delicate, narrow foliage. Some varieties may be bi-color. |
| Digitalis purpurea, Foxglove | Summer | 36" to 72" | Full sun to part shade | Stately plants that are suitable for the back of borders. White, yellow, pink, red, lavender, and purple blooms. |
| Echinacea, Coneflower | June to August | 24" to 60" | Full sun to part shade | Showy, daisy-like purple flowers up to 5" in diameter. Best in full sun, divide when overcrowded. Great in borders. |
| Eryngium planum, Amethyst sea holly | June to September | 12" to 36" | Full sun | The silver blue, teasel-shaped flower heads of sea holly are encircled with shiny bracts. Easily grows in dry, well-drained soil. |
| Eutrochium purpureum, Joe-pye weed | July to September | 60" to 84" | Full sun to part shade | Dull pinkish-purple flower clusters, very attractive to pollinators. Seed heads persist into winter. |
| Heuchera, Coral bells | June to July | 12" to 18" | Full sun to part shade | Grown more for the interesting shades of foliage than the slim stems of tiny bell-like flowers. |
| Hemerocallis sp., Daylily | Late spring to fall | 12" to 36" | full sun to part shade | Thousands of cultivars in every color except blue and pure white. Each bloom lasts just a day. |
| Hibiscus, Hibiscus | July to September | 48" to 60" | Full sun | Hardy hibiscus is a woody perennial with large, showy blooms (6"-10") in in white, pink, and red combinations that bloom for one day. Many blooms are open at any time. |
| Lavandula angustifolia, Lavender | June to August | 24" to 36" | Full sun | Gray-green foliage with whorls of tiny, fragrant flowers in purples, pinks, white, and yellow. |
| Lilium asiatica, Asian lilies | June to July | 12" to 48" | Full sun to part shade | Large star-shaped blooms atop long stems, great cut flowers. Susceptible to the Lily leaf beetle. |
| Lilium oreintalis, Oriental lilies | August | 12" to 48" | Full sun to part shade | Large star-shaped blooms atop long stems, great cut flowers. Susceptible to the Lily leaf beetle. |
| Lobelia cardinalis, Cardinal flower | July to September | 24" to 48" | Full sun to part shade | Erect terminal spikes of large, red, tubular flowers. Needs consistently moist soil. |
| Monarda, Bee balm | Summer | 24" to 48" | Full sun | Pink, purple, red, and white spiky blooms that are very attractive to pollinators. |
| Nipponanthemum nipponicum, Montauk daisy | Mid-summer to early fall | 18" to 36" | Full sun | White daisy blooms from mid-summer to frost. Dark green leathery foliage. |
| Perovskia atriplicifolia, Russian sage | Summer | 36" to 48" | Full sun | Showy, tall, airy spikes of lavender-blue flowers with finely-textured foliage. |
| Platycodon grandiflorus, Balloon flowers | Late summer | 12" to 24" | Full sun to part shade | Star-shaped white, pink, or blue blooms from puffy buds. |
| Polemonium reptans, Jacob's ladder | Late spring to early summer | 12" to 36" | Full to part shade | Loose clusters of bell-like flowers in shades of white, pink, yellow, or blue. Low maintenance. |
| Pycnanthemum sp., Mountain mints | July to September | 12" to 36" | Full sun to part shade | Best flowering in full sun, will bloom in bright shade. Pink blooms are a favorite of pollinators |
| Rudbeckia hirta, Black-eyed Susan | June through October | 12" to 36" | Full sun | Large, daisy-like, golden blooms with black centers. Good cut flowers. Does not reproduce true from seed. |
| Sanquisorba canadensis, Canadian burnet | June through October | up to 6' | Full sun or part shade | Great for back of a border with cream colored flowers that resemble bottle brushes. |
| Sedum sp., Stonecrops | August to November | 6" to 24" | Full sun | Hardy succulents with fleshy, water-storing leaves. Great for rock walls and gardens, borders and containers. Divide in early spring. |
| Solidago, Goldenrod | Mid-July to September | 36" | September to November | Tall yellow spikes of tiny yellow blooms, often mistaken for the allergy-inducing ragweed. |
| Stachys officinalis, Betony | July to September | 18-24" | Full sun | An easy-to-grow herb with late-summer spikes of purple flowers that are loved by pollinators |
| Tricyrtis hirta, Toad lily | Late summer to early fall | 24'" to 36" | Shade | Fuzzy, ear-shaped leaves combined with the mottled, curiously shaped mauve flowers at the tips of the stems. Self-seeds. |
Division
- Most perennials will benefit from division every 3-4 years.
- Spring blooming perennials may be divided in the very early spring, after flowering, or in the fall.
- Perennials that bloom later in the season can also be divided in the early spring or after flowering.
- Plants do best if they are divided when the weather is cool and wet to lessen the amount of stress on the plant.
- Plants should be divided six weeks before the ground freezes to give the plant time to set new roots.
- Prepare new holes before dividing the mother plant so that roots don't remain exposed to the air and sun longer than necessary.
- New holes should be twice the width of the root ball.
- Perennials may be cut back to 6" prior to division.
- Use a spade or a sharp knife to divide clumps or separate rhizomes.
- Make sure that the crown of the plants are placed at the same depth in the soil as it was prior to division.
- Newly divided plants should be watered immediately after re-planting and then receive at least 1" of water per week until the ground freezes.
- A layer of mulch will help the soil to retain moisture.
Despite good cultural practices, pests and diseases at times may appear. Chemical control should be used only after all other methods have failed.
For pesticide information please call UConn Home and Garden Education Center weekdays, in Connecticut call toll free 877-486-6271. Out of state call 860-486-6271.
UConn Home and Garden Education Center, 2019