Monarchs, Migration and Milkweed

The monarch butterfly heads northeast from Mexico on its annual migration in late February arriving in Canada in late June or early July. These spring migrating butterflies only live two to six weeks so the migration means stopping along the way to lay eggs on milkweed plants to keep the generations going. The monarchs who finally arrive in Canada in the summer are the great-great-grandchildren of the ones that left Mexico in February.

It takes four days for eggs to hatch into caterpillars. For the next two weeks caterpillars will munch on milkweed until they mature and wrap themselves in a silk chrysalis. Ten days later they emerge from this cocoon as a fully formed monarch butterfly.

Isn’t that amazing? From a speck of an egg to a caterpillar to a butterfly in a month!

I talked to one gardener in Ontario who actually saw an egg hatch. Imagine seeing a baby monarch drying its newborn wings in the sunshine! An experience of a lifetime and it can be yours for the price of a plant.

For their migration to be successful they need to have milkweed plants to lay their eggs on. When the larvae hatches it is the milkweed plant-and only the milkweed-that provides the food the caterpillars must have. Without milkweed monarchs would have nowhere to land, recover and reproduce. They would go extinct. As gardeners we can help by planting milkweed in our yards.

A monarch caterpillar is crawling over milkweed blossoms.

Just when you thought it couldn’t get more interesting it does. Towards the end of the summer the monarchs hatch out a “super generation” that will live for seven or eight months instead of a few weeks. These super monarchs (though all butterflies are pretty super) make the entire journey to Mexico and live long enough to begin the return journey north in February.

How do they know where to go? And when they return in the spring, how do they know where the milkweed patches are that their great-great-grandparents landed on all those months ago?

These are wonderful questions to meditate on while planting patches of milkweed in our gardens.

Milkweeds Asclepias tuberosa are a perennial native to NorthAmerica and hardy to garden zones 3 -9. Clusters of fragrant flowers come in a variety of colours including pink, white and original orange. The plant grows to heights of 60-90 centimeters (2-3 feet).

Veseys in PEI, Canada offers tubers for sale along with the following advice

Plant 15″-18″ apart with the top of the tap root about 1/2″ to 1″ below soil level and digging deep enough to plant the carrot-like root vertically without coiling or breaking the roots. Mix a couple teaspoons of bone meal into the planting hole if desired. Grows best in full sun, in sandy, well drained, soil.

May be difficult to move without damaging the root system if they have been planted for a long time. If necessary transplant only when dormant or propagate by seed.

Blooms July – August. On a large plant, you could easily find several butterflies at any one time. Once established, these members of the milkweed family are extremely drought tolerant and very long lived.

Veseys offer a collection of three tubers each equally attractive to butterflies, but producing different colors of blossoms. Descriptions and images below are from Veseys.

Incarnata Butterfly Plant

Asclepias

Perennial

Bright, candy-pink flowers. Also known as Milkweed, the Butterfly Flower attracts many types of butterflies, but is best known for being the sole host plant of the famous Monarch Butterfly. Large clusters of flowers will bloom for many weeks and are followed by attractive green seed pods. Plant in a permanent, full sun location and cross your fingers, you just might be rewarded with a visit from a Monarch Butterfly!

Ice Ballet Butterfly Plant

Asclepias

Perennial

Pure, bright white flowers. Also known as Milkweed, the Butterfly Flower attracts many types of butterflies, but is best known for being the sole host plant of the famous Monarch Butterfly. Large clusters of flowers will bloom for many weeks and are followed by attractive green seed pods. Plant in a permanent, full sun location

Orange Shades Butterfly Flower  This one is available by seed instead of tubers.

Ascleipas tuberosa

Perennial

Sunny orange blooms. This is a must-have for the butterfly garden! Commonly called milkweed, it is the exclusive diet of the monarch caterpillar. We have, in fact, seen several such caterpillars in our field trials! An impressive late summer flowering border perennial. Flowers the first year. Reaches a height of 40” by second year. Approx 200 seeds/pkg

Want to know more? Here are a couple books that are worth checking out…