Monday, April 8, 2019

Grow Milkweed for the Monarchs

Growing Milkweed for the Monarch Butterflies

The first time I saw a Monarch butterfly up close in my garden, I was completely awestruck by its grace and beauty. Their bright orange wings and solid black borders make the Monarch butterfly one of the most recognizable butterflies. And they are, without a doubt, little migrating miracles.

To help them along their migration path, draw them into your garden by planting Milkweed.

The Great Migration

The Monarch Butterfly is a widespread tropical insect found in all parts of the world. There home range spans as far north as Canada. They are the only known butterfly to make a two-way migration as birds do. They are one of the few insects capable of making trans-Atlantic crossings. That's a yearly 3,000 mile trip across North America for millions of Monarchs!

The great migration begins around the month of October, or earlier if the weather turns cold sooner. East of the Rockies, the Monarchs will migrate to Mexico and Florida to escape the cold winters.  West of the Rockies, they will migrate to Southern California. This migration is key to the Monarch butterfly's yearly life cycle.  Other species of butterflies make much shorter migrations or none at all. 

Dwindling Numbers

According to the National Wildlife Federation, the number of Monarch butterflies has dwindled by nearly 90% over the last 20 years. The biggest threat to them is the decrease in the Milkweed plants which is the host plant that they depend upon to survive.

So what is a Milkweed plant?

Common Milkweed, or Asclepias syriaca, is an upright perennial plant growing two to six feet tall. Most people associate the Common Milkweed with the word “Milkweed.” It's a herbaceous perennial with fragrant pink to purple to orange flowers that bloom from May to August. The stems vary from green to purple and are covered with fine, white hairs. 

The Milkweed plant is moderately deep-rooted and spread by a broad network of lateral roots or rhizomes. The Milkweed grows, sets seed and then naturally dies back in the fall, only to sprout up again in spring.

In past years, the Milkweed plant was commonly found growing near fence rows, on roadsides, in fields, and pastures and prairies. But because of the popular use of pesticides these days, there is now a shortage of safe habitats for milkweed plants, and therefore, a shortage of food for the Monarchs.

Types of Milkweed

While there are over 140 known species of Milkweed, all members of the genus Asclepias can be used as a monarch butterfly host plant. 

These include:
  • Common Milkweed (Asclepias syriaca) Zones 3 – 9. 
  • Pink flowers
  • Butterfly Weed (Asclepias tuberosa)  Zones 3 – 9. Orange flowers, some cultivators have yellow flowers.
  • Swamp Milkweed (Asclepias incarnata)  Zones 3 – 6. Pink flowers.
  • Smooth or Prairie Milkweed (Asclepias sullivantii)  Zones 3 – 7 Bright pink flowers.
  • Showy Milkweed Asclepias sullivantii)  Zones 3 -9 Pink and purple flowers.
  • Bloodflower or Tropical Milkweed (Asclepias syriaca)  Zones 9 – 11 Red to orange with yellow flowers.

Why is the Milkweed so popular with Monarch Butterflies?

Monarchs are also known as Milkweed Butterflies, so it comes as no surprise that the Milkweed plant is their major food source. Milkweed gives the Monarch both food and shelter.

Adult Monarchs love the rich source of the nectar of the Milkweed. They will lay their eggs, up to hundreds of them, on the underside of the milkweed leaves. 

When the eggs hatch as larvae, usually in four to five days, they eat their eggshells first, then the caterpillars feast on the milkweed plant. They enjoy the Milkweed's large, fleshy leaves and will stock up on them for the day when they become those beautiful butterflies.

The sticky white sap inside a Milkweed plant is slightly toxic, and because the caterpillars eat the leaves, the Monarch butterfly is also poisonous. Although this doesn't harm the caterpillar, it serves as a great warning to their predators who have learned that the Monarch butterfly will taste bad or may be toxic.


The transformation

There comes a point where the caterpillar stops eating, hangs upside down from a twig or leaf and spins itself a silky cocoon. Within that protective casing, it will then transform its body into a butterfly.


Growing Milkweed From Seed

Milkweed plants grown from seed will concentrate on growing sturdy roots in the first year.  You may want to keep an eye on the new plants as the size of the new plant will not be sufficiently grown to feed a caterpillar.  This second year the plant will usually flower and is strong enough to handle the caterpillars.

Milkweed seeds need a period of stratification in order to successfully germinate. This happens naturally in nature as the seeds fall to the ground where they remain all winter. 

You can achieve this same result by storing your seed packet in the refrigerator for six weeks prior to sowing.   If you are sowing the Milkweed indoors and then transplanting out, you cannot skip the stratification step.

Several Ways to Sow Milkweed from Seed


My preferred method is to winter sow them. Using the winter sowing method, the seeds will sprout outdoors on Mother Nature's timing. Those seedlings will be stronger than seeds sown indoors simply because they are already acclimated to the outdoors.

To read our detailed article on winter sowing, click here.

Direct Sowing

The best time to direct sow your Milkweed seeds into your garden spot is when the fall weather is consistently cool but the freeze hasn't hit yet. You'll need to cover the seeds lightly with soil and keep them watered until the ground freezes.

Because there is no protection for the seeds with the direct sowing method, your germination rate will be much lower with this method. But if you have plenty of seeds, it may be worth the ease of direct sowing.

Sowing Indoors

Sow your stratified seeds 6-8 weeks prior to your estimated last frost date.

Here are some indoor sowing tips.

  • Barely cover the seeds. The seeds need light to germinate.
  • Spray lightly with water a few times a day until the seeds germinate, usually 14 to 28 days.  Spraying lightly reduces the chances of dislodging the seeds from the soil.
  • Placing bottom heat under the seed flat will aid in quicker germination.
  • Place the trays under grow lights and keep the soil moist.
  • Keep the seedling tops an inch below the grow lights to prevent them from becoming thin and leggy.

Tool Set

Planting Out the Seedlings

  • When the seedlings have four true leaves, they are ready to go outdoors, weather permitting.

  • Harden off the seedlings before exposing them to the outdoors full time. For a detailed article on hardening off seedlings, click here.

  • Transplant outdoors when all danger of frost has passed and the temperature range is between 70 and 85 degrees.

  • The soil should be rich in organic matter. To read a detailed article on soil amendments, click here.

  • Space the plants 12” to 18” apart. They will grow roughly to 36 to 48” tall.

  • Keep watering well for the first few months until the roots are firmly established.

Other Care Tips of Milkweed

  • The sap of Milkweed can be harmful to both the skin and the eyes. Gloves are always recommended when handling this plant.

  • Milkweed can tolerate drought, but prefers fairly moist well-drained soil.

  • Fertilizer. Milkweed is not a heavy feeder. A single application of a balanced fertilizer in the spring should be all you need in poor soil. In rich soil, no fertilizer is usually necessary.

  • Add an extra layer of mulch for the winter months to give the crown and root zone some extra protection.

  • The Milkweed plant can be rather invasive. You may need to remove any rhizomes that spread into unwanted areas.


Since the seeds are contained in a pod that bursts sending seeds into the air in all directions, some gardeners prefer to deadhead the seed heads before that happens. If you're not concerned with the milkweed self-sowing, no deadheading is necessary.


Gardener's Choice. You can cut your plants back in the fall if you prefer a tidy appearance. Many gardeners choose not to prune the plants until the spring as the birds and small animals can use their natural fibers and seed fluff for their winter nests.

Collecting Milkweed Seeds

Timing is important when harvesting seeds from your Milkweed plant. If the seeds are collected too soon, they may not be viable.The seed pods split open between September and October. 

Collect the seeds in the Fall when the pods, which may be green or brown, open easily. The seeds should be brown and tough. If the pods are white or barely green, come back later.

Remove the fluffy white coma which look like little parachutes and only store the brown seeds. 

You can use the old gardener's trick of shaking the seeds in a paper bag to separate the seeds from the fluff.

Other Ways to Help the Monarch butterflies

The NWF, National Wildlife Federation, has a website with a variety of information about Monarch butterflies as well as a link to report your sitings and even upload pictures of their migration through your area. 

 Here's the link:

Scroll down and hit the "Get Involved" tag.


All gardeners have a deep-seated love of nature, and there's something to be said for combining a love for plants and a love of being a steward of the earth. Growing Milkweed for the Monarch migration is a great way to do just that!

This post may contain Amazon affiliate links and as an Amazon Associate I earn from qualifying purchases without costing you anything extra.

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