Plant “Enough” Milkweed for Monarch Butterflies

From my observations last fall, I realize the importance of planting enough Common milkweed (Asclepias syriaca) for a variety of pollinators in my garden. But the abundance matters most for Monarch butterflies, being it is their host plant.

In our yard we seemed to have had more Monarch Butterflies in 2021 than in 2020. But it may seem like this only because I intentionally planted milkweed and other pollinator-friendly flowers years ago to attract more butterflies close to the house, for my enjoyment. 

Aside from Common milkweed, Monarchs visit Swamp milkweed and Butterfly Weed and can lay their eggs on both plants. But again, Common Milkweed is their preferred plant. These plants grow near our house and in the fields, and are a good sources of nectar. They also grow in smaller amounts since other plants have pushed them out over the years.

In my garden, if there are numerous caterpillars on the leaves of Common milkweed, there may be times when there is not be enough food/leaves for all of them. When this happens, they could starve. Of course, on our land the caterpillars could make the long journey to field where there is "some" Common milkweed growing, but the chance of them making it the distance seems pretty unrealistic, and there are plenty of predators awaiting them: birds, mice, ants, spiders.

Caterpillars, apparently, can go up to 24 hours without food without any negative effects. I don't think this is long. I could have brought milkweed leaves from the field (and did) to feed them, but this needed done frequently, until the caterpillars were done eating after about 2 weeks. It grew kind of tiresome. When the food grew short I could have also taken the caterpillars up to the field and left them on the milkweed and let them do what they do naturally. I chose instead to raise them inside, so I could ensure they reached the next stage of their life and, in time, was able to release them as adult butterflies. I don't plan to do this every year, however. So I will need to introduce more milkweed in my garden, or remove what I have so they are attracted only to areas where there is enough food. I imagine all gardeners who are planting milkweed may not observe the happenings on their plants. This is unfortunate for the caterpillars when there's isn't enough food. But for gardeners who plant milkweed merely for the abundance of butterflies and bees coming to the plant, they may not care.

Another reason I raised Monarchs again, last year, was because I noticed that some caterpillars were disappearing on my plants over night, likely due to predators. But they have to eat, too, right? Still, I planted this plant to help the Monarchs. That said, I still had an abundance of eggs and caterpillars that seemed to arrive daily, on what little plants I do have, which I honestly thought was "enough".

A mother Monarch will lay about 100-300 eggs a day. And in proper conditions she will lay only one egg per plant to ensure her offspring have enough food (source: Save Our Monarchs). But if you read further there have been observations of many egg dumps on one plant.

I can tell you from my close observations, that had I not helped the caterpillars on my plants near the house, they would have starved, or, of course, been eaten by something. Normally, in nature, Milkweed is found growing in abundance in patches in the wild. This may not be so much a problem. But then, Common Milkweed areas are in decline due to agricultural fields, herbicides, increased mowing, etc., so there's is cause for concern on whether or not in the greater picture there is "enough" food for Monarch's.

If you introduced this plant to your garden, I hope you have plenty of other pollinator-friendly flowers to help Monarchs, too, but also that you planted "enough" of the Common Milkweed plant.