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Jessica Walliser

Gardeners can ease butterflies' plight

Jessica Walliser
| Saturday, Oct. 31, 2015, 6:07 p.m.
The distinctive white, yellow, and black striping on the monarch caterpillar
Jessica Walliser
The distinctive white, yellow, and black striping on the monarch caterpillar
Purple milkweed
Jessica Walliser
Purple milkweed

Unless you've been living under a rock with the slugs and earthworms, you're most likely aware of the struggle of the monarch butterfly.

According to the National Wildlife Federation, the monarch butterfly population has plummeted by more than 90 percent in the past 20 years.

These beautiful insects have been dealing with the perils of habitat loss and pesticide exposure here and in their wintering grounds in Mexico. Each autumn, the monarchs fly to warmer climes via one of the insect world's most incredible mass migrations, with millions of insects making the journey of up to 3,000 miles.

The next summer they return to our backyards to breed. Several generations are born in the East before cold weather arrives and the monarchs again start their epic migration.

Home gardeners might wonder what they can do to help the monarch butterflies, whose survival clearly is threatened. The answer is simple: Plant lots of monarch-friendly flowering plants.

Next summer, when the migrating monarchs return to Pennsylvania, they'll be searching for flowers. The adult butterflies need the carbohydrates in nectar before breeding can begin. Many plants — such as liatris, coneflower, asters, buttonbush, lantana, tithonia and purpletop vervain — are excellent nectar sources for the adults. Be sure to include a variety of flowering plants in your garden with a range of bloom times, and flower colors and shapes.

To lay eggs, female monarchs need a special plant — milkweed. Plants in the genus Asclepias are the sole food source for monarch caterpillars. Female butterflies will only lay eggs on the leaves of members of the milkweed family, and unfortunately, much of North America's once-plentiful milkweed has been replaced with lawns, buildings, roads and farmland.

By introducing milkweed into our gardens, we're providing the butterflies with a nectar source and a larval food source. The caterpillars are completely dependent on milkweed for their maturation and remain on the plants until they are ready to pupate several weeks after hatching.

The distinctive white, yellow and black striping on the monarch caterpillar make it hard to miss, and if you're lucky, you'll discover several caterpillars on your milkweed plants each season. It's fun to watch them grow, knowing your garden is playing an important role in the survival of this incredible insect.

There are several milkweed species that are good choices for the garden and the monarch.

Common milkweed ( Asclepias syriaca) is probably the easiest to grow, but it's also one of the most aggressive. Plant this milkweed only if you have plenty of room for it to spread. It reaches up to 5 feet in height, has large balls of pinkish purple flowers in summer, and does quite well in poorly drained soil and regular garden soil. As with most milkweeds, the flowers are followed by tapered seed pods.

Butterflyweed ( Asclepias tuberosa) is a great choice for gardeners with limited space. The orange flowers are born on 2-foot-tall, clump-forming plants. Enjoying full sun, this species is great for dry and moist sites.

Swamp milkweed ( Asclepias incarnata) also is called pink milkweed. This easy-to-grow perennial has large clusters of bright pink blossoms. Though it's said to need lots of water, mine is growing in a well-drained garden area and seems to do just fine. It reaches 3 to 4 feet in height.

One of my favorite milkweeds is purple milkweed ( Asclepias purpurascens). The bloom clusters are a deep magenta and appear earlier than other milkweeds. The plant reaches 4 feet in height and is not as aggressive as common milkweed.

Most perennial milkweed species are easily started by collecting the seeds from a friend's plant, or by purchasing them from a seed source such as Ernst Conservation Seeds (ernstseed.com) or Botanical Interests (botanicalinterests.com). The seeds are ready to harvest from a mature plant as soon as the pods dry and split, but they will not germinate unless they've been exposed to cold temperatures for several months. This process, called cold stratification, naturally occurs when you tuck the seeds under a very light layer of soil out in the garden anytime between September and Christmas. The seeds will sit dormant through the winter, and come spring, they'll germinate on their own.

It's possible to divide established milkweed plants or purchase starter transplants from a nursery. But most milkweed species resent being transplanted, and trying to dig up a wild plant and move it into your garden is a recipe for disaster (and illegal, if you don't have permission from the landowner).

Milkweed is almost always best started from seed.

Plant milkweed — not only is it good for your garden, it's essential for the monarchs.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” with Trib Home and Garden Editor Doug Oster at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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