Imagine only surviving on one food source? Seems impossible, right? Most of us would get sick and tired of only eating one type of food, but Monarch butterflies are different. Not only do Monarch butterflies exclusively use the foliage of Milkweed to lay their eggs it is the only food source for Monarch caterpillars before they transform to butterflies.
Milkweed is found all over the U.S. and can aggressively spread given the right conditions. The flowers and heights of Milkweed vary by species with more than 140 different Milkweeds in the U.S.
Here in New Jersey, there are two common Milkweeds that one can easily find in the landscape or in someone’s garden. The first is considered a weed by Rutgers NJ Ag Extension Common Milkweed (Asclepias syriaca) but highly treasured for feeding the Monarchs.
I find the transformation of the Common Milkweed to be fascinating especially when it goes to seed. I have planted Common Milkweed in my garden with poor success in growth. This is surprising since it is easy to grow and will tolerate most soils. Common Milkweed loves direct sun and self-seeds.
Another type of Milkweed that you will see in NJ is Orange Milkweed or Butterfly Weed (Asclepius tuberose.) Orange Milkweed is short at 1 to 1 ½ feet tall and has a profusion of small bright orange flowers. Common Milkweed in comparison is tall about 3 to 5 feet tall with it climbing even higher.
Since you can grow Milkweed all over the U.S. check out http://monarchwatch.org/bring-back-the-monarchs/milkweed/milkweed-regions-seed-needs/ what type of Milkweed does best in your region or http://monarchbutterflygarden.net/milkweed-plant-seed-resources/ to get resources where to buy milkweed along with photos of many of the varieties.