Two main types of peonies are commonly grown in gardens: herbaceous peonies and tree peonies.  Herbaceous peonies die to the ground every winter and regrow in spring.  Tree peonies are shrubs; their flowers bloom early in spring on woody branches.  Today we will discuss the herbaceous, perennial peonies whose flowers appear in early summer.

Several species of peonies exist.  One of the first grown in gardens was European, Paeonia officionalis (the Memorial Day Peony).  The single form, with five petals, was grown in the Middle Ages.  Thomas Jefferson grew the double form in his garden.  In the early 19th century several garden forms of the species Paeonia lactiflora arrived in Europe from China and Siberia.  French nurserymen hybridized these with P. officionalis to develop new varieties.  Several are grown today as valuable heirlooms, such as ‘Duchesse de Nemours’, from 1856.  In the 20th century America became the center of hybridization for peonies; now hundreds of cultivars are available.

Herbaceous peonies are quite hardy, to USDA climate zone 2.  The long-stemmed, large flowers are excellent cut.  Three basic flower forms of peonies include: single or semi-doubles with one or two rows of petals; Japanese, with five petals and large stamenoids; and double flowers with many petals.  Older hybrids come in red, pink, coral, mauve, white and cream.  A group of newer hybrids are inter-generic crosses of tree peony species and herbaceous species.  Their color range is greater and includes some very nice yellows.  Double peony flowers can become very heavy with rain in the spring and are best staked or supported by cages.

Peonies are an excellent choice for organic gardeners, as they are subject to few diseases or pests.  I have seen powdery mildew on some peonies locally, but they were growing in a raised bed and in part shade.  Their roots were very dry in that situation.  Botrytis is another disease occasionally seen in cool, humid weather.  Leaves and buds wither and turn black, flowers turn brown.  Copper fungicide will cure this.  To prevent botrytis, clean up all leaves in the fall and plant in sunny, airy spots in the garden.

Herbaceous peonies are long-lived, growing in the same spot for decades.  Generally, peonies are easy to grow, well-adapted to our alkaline soil, cool spring weather and cold winters.  Good garden soil is helpful; be sure remove quack grass and other weeds before you plant.  Soil should be well-drained and moisture retentive.  Full sun is best.  Dig a good-sized hole, add compost or well-rotted manure and mix a small handful of bone meal into the soil 4 to 6 inches below the roots.  Plant the roots with eyes up, no deeper than 3 inches; one inch deep is best.  If peonies are planted too deeply they will not bloom.  Place individual plants about 3 feet apart.

August, September and October are the best months to divide and replant peonies here in Montana.  In the northeast section of the state, where winters are colder, August and September are probably best.






Soil pH is a measure of acidity or alkalinity.  This measurement can range from a very low pH of 1.0 to an extremely high pH of 14.0.  7.0 is considered neutral and several vegetables will thrive in soil with a neutral pH.  Some vegetables do prefer a more acidic soil while others prefer a more alkaline soil.  Fortunately most will grow and produce well in a pH range of 5.5 to 7.5.   Areas with high rainfall, such as coastal Washington, tend to have acidic soils high in organic matter, while areas with lower rainfall, such as most of the mountain valleys in Montana, tend to have alkaline soils low in organic matter.  Here in the valleys of the Flathead region, where most of us garden, soils tend to be somewhat to highly alkaline.

Before you amend your existing soil to plant vegetables it is a good idea to test the pH.  An easy way is to purchase a test kit.  Most of them are easy to use and give fairly accurate readings.  Your county extension agent can do a soil test also.  Once you have determined your soil pH and which crops you intend to grow, you can amend your garden soil.  Adding lime will increase pH and make acidic soils more alkaline; adding sulfur will lower pH and make soils more acidic.  Organic matter usually helps reduce alkalinity.  Aged manure, pine needles, compost and coir dust are a few amendments that will help do this while they improve soil structure and encourage beneficial soil micro-organisms.  If your garden is divided into separate beds or raised beds, it is easier to adjust the soil in each bed for what you plan to grow.   I rotate my vegetable crops in a four-year rotation plan, so I try to keep a basic soil pH around 6.0 to 6.5.  This way I can grow almost every vegetable, but I slightly adjust pH each year before growing a particular plant.  For example, I add sulfur before growing potatoes.  Conversely, I add a small amount of lime before planting any of the Brassica family (Broccoli, Brussels sprouts, cauliflower, etc.).   Having soil pH correct for each crop will reduce pest and disease problems as well as increase yields.

Here is a listing of pH tolerance ranges for specific vegetables.  (The optimum pH for each is usually the median between the two extremes.)  I have listed vegetables preferring more acidic soils first and those preferring more alkaline soils last:

Potatoes, 4.5-6.0; sweet potatoes, 5.6-6.5; horseradish and rhubarb, 5.5-6.8; butternut squash, carrots, corn, eggplant, lettuce, peanuts, peppers, pumpkins and watermelon, 5.5-7.0; cucumbers, garlic, winter squash, and tomatoes, 5.5-7.5;  celery, 5.9-6.9; soybeans and strawberries, 6.0-6.8; onions, radishes, shallots and spinach, 6.0-7.0; beets, any of the Brassica family, peas, summer squash, Swiss chard, and zucchini, 6.0-7.5; okra, 6.0-8.0.