Polygala

( pall - ee - GALL - uh )

At-A-Glance Information

This genus of evergreen shrubs commonly called Milkwort or Snakeroot needs full sun to light shade and regular water. They are grown for their colorful, asymmetrical, bird-shaped flowers that look a little like those on the Lathyrus (or Sweet Pea) plant. Polygala shrubs are distributed throughout the world in temperate and tropic zones.

Polygala Species and Varietals

The genus Polygala includes between 350 and 730 species and is a member of the plant family Polygalaceae. The genus name is derived from the Greek term 'much milk', as the plant is thought to increase the yield of milk from cows that consume it. The genus was first described by Carl Linnaeus in 1754, and since then, many species of flowering shrubs have been added to the genus, possibly incorrectly, due to similarities in flower shape (which is why the species count in the genus varies so widely). Polygala ideal growing zones vary depending on the species; for more information, see the descriptions below. To find your zone, click here: Zone Map.

Polygala x daimaisaiana (Sweet Pea Shrub)
This species grows in zones 8, 9 and 12-24; reaches 3-5 feet tall and wide. Leaves are grey-green and pink-purple flowers bloom throughout the summer and fall seasons. Cut back hard in late wintertime to create a more compact plant with bushier growth. Great as a filler in landscapes.

Polygala fruticosa 'Petite Butterflies'
This species grows well in zones 8, 9 and 14-24 and is native to South Africa. It reaches 2-3 feet tall and wide, with rounded grey-green leaves. Blossoms are purple-pink with pale pink centers, and appear almost year-round in mild areas. In other places, blooms appear most profusely from spring through fall. Great near coastlines and provide interest to cut flower arrangements.

Caring for and pruning Polygala shrubs

Plant Polygala shrubs in full sun to partial shade. They should be getting at least 4-6 hours of sun each day for optimal growth and flowering. Check the requirements of the species before planting, however, as some varieties can take more shade. Soil should be well-draining and rich in organic matter with a pH of between 6.0 and 7.5 (acidic to neutral). Keep soil consistently moist, but not water-logged; Water deeply when the soil feels dry. Apply a layer of organic mulch to assist with soil moisture retention, keeping it away from the stem to prevent rot.

These shrubs can benefit from a feeding with a balanced, slow-release fertilizer each spring to support new growth and flowering. These shrubs can grow in containers or in-ground, and only need to be pruned as needed. They have a beautiful, rounded natural shape. Regular deadheading will encourage more blooms to be produced. More extensive prunings to reduce the size or rejuvenate the plant should be completed in late winter to early springtime. Any damaged or leggy growth can be removed from the plant at any time of the year.

Propagation

Polygala can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub, follow the instructions below:

Propagating Polygala by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
In spring or fall, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Polygala by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 14-28 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.