by Cheryl Moore-Gough, Extension Horticulture Specialist, retired
and Robert E. Gough, MSU Professor of Horticulture

Although Montana is not the easiest place to grow flowers, with care – the sort of maintenance, watering, staking, and feeding described here – you can have beautiful plantings in your yard. The extensive charts in this publication describe many perennial and biennial flowers that grow fairly well under our conditions.

BIENNIALS AND PERENNIALS CAN BE USED TO FILL in between shrubs, as a border to shrubs in foundation plantings, and as flower borders at the edges of lawns and along sidewalks and driveways. All of the plants were brought into cultivation from wildflowers and this cultivation and domestication has generally led to larger plants and flowers. In some cases domestication has led to highly specialized flowers that no longer set seed. Such plants can only be propagated vegetatively.

Daffodils are a perennial that grows great in Montana
Daffodil (Narcissus spp.) is the name given narcissi with prominent trumpets. All daffodils are narcissi—but not all narcissi are daffodils.

Herbaceous perennials have diverse cultural requirements but all commonly die back to the soil line during our Montana winters. Their perennial roots regenerate a new top each spring. Plant perennials in spring or fall, though fall planting is usually preferable. Biennials often form a rosette of leaves that remain close to the ground during the winter of their first year. The second season the plants produce flowers and seed stalks, then die. The hardier biennials can be sown in spring and transplanted to areas where they will bloom the following year. All biennials can also be transplanted to the garden in the spring of their flowering year and treated as you would treat annuals. Pull them as their blooms fade to make room for other plants and to keep the garden neat.

Although soils can be amended somewhat, most biennials and perennials have specific soil requirements so choose the right plant for the site you have in mind. Most do well in a well-drained loamy soil high in organic matter and adequately supplied with nitrogen and phosphorus. Prepare the soil by deep tilling to a depth of about 20 inches to encourage normally shallow roots to grow deeper. If the soil is poorly drained, incorporate some coarse sand into the area at planting. Most of these flowers do best in a nearly neutral soil, but Anemone hupehensis, ‘Japonica’, hollyhocks, and Iris prefer a slightly alkaline soil.

General Maintenance

Survey the garden each spring. Press back into place plants that have heaved out during winter. Divide or replace plants that are weak or crowded and remove dead or diseased plants and plant parts as soon as they appear.


Most of these plants require moderate but thorough watering once each week to wet the soil to a depth of at least a foot.


This is necessary to support weak and floppy stems and to protect tall flower spikes from being bent or broken by strong winds. Dahlias, asters, delphiniums and others require tall, strong stakes of bamboo or steel. Peonies can be supported by large wire hoops surrounding the plants. Never tie stalks tightly to stakes, which could crush their stems. Bare wire and small-diameter twine can cut stems. Instead, use soft waterproof tape, large-diameter binder or baler twine, or strips cut from discarded panty hose.


Renew your gardens every several years to prevent perennial plants from becoming crowded and producing inferior blooms. You can renovate the gardens in spring or fall, but fall is usually preferable since you may have more time then and you can plant new bulbs during renovation. Remove the perennials and work liberal quantities of compost or rotten manure into the bed, then divide the plants if necessary and reset them. Peonies, Dicentra (bleeding hearts) and Oriental poppies often do poorly if disturbed, so leave them in place during renovation. Some perennials are comparatively short-lived. Columbines, lupines, delphiniums and some Linum and Daphne often die out after several years. Others, like Iris, Phlox, and the hardy asters can live for many years. Lift and divide these every year or two to keep their blooms large and healthy.


Removing the spent flower stalks (deadheading) from perennials tidies the garden and prevents the maturation of seed and allows the plant to shunt more food reserves into the crown and root areas for better growth next year. Deadhead your plants as the flowers begin to fade.


Apply a complete fertilizer such as 8–8–8 or 5–10–10 as soon as spring growth begins at the rate of about 2 pounds per 100 square feet. Fertilize again in early summer. Do not apply fertilizer after late June since it can stimulate late vegetative growth that could cause the plant to enter the fall in an immature condition. Several inches of partially rotted manure or compost, applied as a mulch over the plants in the fall when the top-growth has died down, supplies some nutrients and adds valuable organic matter to the soil to improve plant growth.

Do not apply manure or compost mulch to plants susceptible to crown rots. These are so noted in the following table.

Montana is not the easiest place to grow flowers, but with care you can have beautiful plantings in your yard. The chart on pp. 2–5 describes some perennial and biennial flowers that will grow fairly well under our conditions. Some species can be classed as either perennial or biennial depending upon soil fertility as well as genetics.


(arranged alphabetically by scientific name)

Copyright © 2011 MSU Extension

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File under: Yard and Garden (Flowers) Reviewed March 2010 300-411SA