What IS A Perennial?
Unlike annuals, some perennials do not flower their first year from seed. Since they need to go through a cold period to flower, they must survive through a winter in order to flower and produce a seed for the next generation. What makes a plant a perennial then? First, again that they carry out their life cycle in more than one season. And secondly, that they possess the Cold Hardiness to survive through the winter in a climate.
Therefore, plants that are perennials in some climates, my not be in climates that are colder.
The City of Williston has been zoned:
USDA Zone 4a (-30 to -25 F)
Why Plant perennials?
The most common reason for planting perennials is often the same for everyone. Perennials, because of their ability to survive through a winter can ensure that one does not have to continue to plant those areas of the landscape every single season.
The maps above of ND and MT will enlarge if you tap or click on them. You can then find your appropriate USDA Zone.
Perennials, when compared to annuals, have some drawbacks. The first of which being their expense. Filling an area with perennials can cost you much more in dollars than it would to plant with annuals. However when you consider the fact that perennials, if properly cared for, will continue to beatify that space for many seasons to come, the cost is not nearly so steep.
The other big difference between annuals and perennials is that since perennials do not complete their life cycle in a single growing season they do not have the need to continually flower in order to produce a seed. Because of this, perennials often only flower for a portion of the growing season. This means that some planning should be done in order to ensure that plants are chosen with varying bloom times.
Below you will find two lists of plants. It is often easiest to break choices down based upon how much sun a plant will tolerate. While some plants that are tolerant of full sun will also grow in shade, they might not flower as vigorously, or they may stretch for light, instead of remaining tight with their growth habit.
FULL SUN (a - g):
Aegopodium (Snow on the Mountain)
Asclepias (Butterfly Weed)
Aster dum (Woods Aster)
Baptisia (False Indigo)
Centaurea Montana Blue (Bachelor Button)
Delphinium grandiflorum (Summer Series)
Delphinium elatum (Upright Tall)
Full Sun (h - z):
Heliopsis (False Sunflower)
Lamiastrum (Herman's Pride)
Lychnis (Maltese Cross)
Monarda (Bee Balm)
Oenothera (Evening Primrose)
Papaver (Oriental Poppy)
Perovskia (Russian Sage)
Phlox paniculata (Tall Garden Phlox)
Phlox subdulata (Creeping Phlox)
Physostegia virg (Obedient Plant)
Platycodon (Balloon flower)
Polemonium (Jacobs Ladder)
Pyrethrum Tanacetum (Robinson's Painted Daisy)
Rudbeckia (Black Eyed Susan, Brown Eyed Susan)
Salvia (Meadow Sage)
Saponaria ocym. (Soapwart)
Stachys byzan. (Lambs Ears)
Dicentra (Bleeding Heart)
Lily (Asiatic / Tiger Lily)
Polemonium (Jacob's Ladder)