FINALLY….We are building a list of Milkweeds and relevant information. As of April 12, 2019 every milkweed described here is either for sale or currently growing and will be listed for sale in the next couple of weeks.
Scroll down for info on transplanting your Tropical Milkweed
Asclepias verticillata Whorled
Asclepias verticillata is commonly known as whorled milkweed or horsetail milkweed. The flowers of this plant are loved by many adult butterflies as a nectar source so this makes it a great double-duty plant performing as both a nectar plant and a host plant in butterfly gardens.
Whorled milkweed is native to the US from the Rocky Mountains through the East and is usually found along roadsides, in prairies, on the edge of woodlands and other dry, sunny areas.
It is a herbaceous perennial that is hardy in zones 3-9 (some sources say 4-10). It is shorter than some other milkweeds growing about 2 feet tall. This milkweed prefers full sun but will tolerate partial shade and is drought tolerant.
It will do well in medium moist gardens. When given some room it will make beautiful colonies that are in bloom from mid-summer through fall.
The flowers are white with hints of green and are fragrant. The leaves are thin and in a whorled pattern, usually on a single stem. Asclepias verticillata generally stays vibrant later in the season than many other milkweeds that bloom earlier so it is an important food source for fall-migration Monarchs.
Asclepias speciosa Showy
Showy milkweed is native to all the Western states and Central states as well as into Canada, hardy in USDA zones 4-9.
Asclepias speciosa is a found in roadside ditches, fields, around fence posts, railroad tracks and other abandoned/distressed areas. It is, however, a very pretty and fragrant flowered milkweed with large fuzzy blue-green leaves.
Showy milkweed prefers full sun and will tolerate drought once the plant is established. It can be found in dry areas as well as mesic (medium moist) and will do fine in poor soils but needs good drainage. The mature plant height is about 4 ft (though this can vary widely with different conditions).
As an herbaceous perennial it will die back each fall to return in the spring. Showy milkweed will put on a flower show for several months from summer to fall.
Asclepias tuberosa Butterfly Weed
Butterfly Weed (Asclepias tuberosa) is often confused with Butterfly Bush (Buddleia). They are not the same. Butterfly bush is a large shrub that is a great nectar plant whereas Butterfly Weed is a short milkweed that can be used as a host plant by Monarchs as well as being a nectar plant.
Asclepias tuberosa is a native milkweed to most of the US with the exception being the Northwest. It is a perennial and is hardy in zones 4-9. Some resources include zones 3 and 10 as well in its hardiness range.
Butterfly Weed grows about 1-2 ft high and forms clumps. It is a very well behaved garden plant. Beautiful bright orange blooms appear in June then occasional blooms will occur throughout the summer.
This is one plant that can tolerate a wide range of soil conditions from medium to dry moisture levels. It needs good drainage and is drought tolerant. This is a great milkweed for a sunny dry area. Butterfly weed prefers full sun but will do well in part shade.
Asclepias tuberosa has a tap root (which helps with the drought tolerance) and generally does not like to be disturbed.
Asclepias viridis Spider
Asclepias viridis grows best in Central and Southeastern United States, and is a primary food source for adult Monarchs and their caterpillars, especially in Texas. It’s also commonly called Spider or Green Antelope Horn Milkweed
Spider Milkweed is also a highly attractive host plant for Soldier and Queen Butterfly caterpillars and adults, and serves as a nectar plant for many other butterflies and pollinators, too.
Spider Milkweed is an herbaceous perennial, hardy in zones 4-9. It’s one of the earlier-flowering milkweeds, blooming from May to June. As such, this is a great milkweed to plant for those early-migrating Monarchs. The larger-than-average flower clusters are a unique creamy greenish color, with purple highlights in the center.
Growing 1-2′ tall, this is one of the shorter milkweeds. Spider Milkweed behaves well in the garden, spreading gently. It utilizes a taproot, making it very drought-tolerant. It will thrive in dry to medium-moist soils, but well-drained soil is a must.
Asclepias syriaca Common
Asclepias syriaca is native to most of the US states that are east of the Rocky Mountains (the western exception is Oregon where it has naturalized) and into Canada. It is frequently found in meadows, roadsides, railways, around fence posts, etc, and is hardy in USDA zones 4-9.
Asclepias syriaca usually has just a single stalk and can grow from 2-6 feet tall. The leaves are large and the flowers are pretty pink shades with a very pleasant fragrance. It starts flowering in midsummer and flowers into the fall
Common milkweed spreads by seed but also by underground rhizomes. When you plant this you may find it popping up all around. In a fertile garden setting it can become a real nuisance unless you are prepared to keep it somewhat in check and/or don’t mind its underground spreading habit.
Common milkweed is a good choice if you have enough room for it in a section of your yard/land. It is easy to grow and requires very little or no care once it is established. Some people grow it successfully in large pots (5 gallons or more) and others report that they plant it in their gardens anyway because they just like it and the butterflies do as well.
Common milkweed is attractive to a large range of adult butterfly species as a nectar plant. The butterflies love to feed from the fragrant flowers, so not only will it attract egg-laying Monarchs but also many other types of butterflies.
Common milkweed likes full sun but will tolerate some shade. It will grow in a wide range of soils including clay, rocky, or sandy and prefers good drainage. The water requirements range from dry to medium moisture.
Asclepias incarnata Swamp
Asclepias incarnata is known as Swamp milkweed and is highly preferred by the Monarch butterflies. Other common names include Rose Milkweed or Swamp Silkseed. Queen butterflies may also use Swamp milkweed as a host plant.
As well as being a host plant, Asclepias incarnata is also a great nectar source and attracts many other kinds of butterflies.
Asclepias incarnata is a native perennial milkweed to the most of the US and Eastern Canada and is hardy from USDA zones 3 to 8. Only the far western states of the US fall outside of the native region.
This milkweed has fragrant clusters of small flowers that are loved by many butterfly species besides just the Monarchs. Swamp milkweed will flower the first summer from seed and will flower all summer.
Swamp milkweed can vary greatly in height anywhere from 2-6 ft but is probably most commonly seen around 3-4 ft tall. They will die back in the fall to return from the ground in the spring.
Another great thing about Swamp milkweed is that like many of the milkweeds it is very attractive to many species of butterflies as a nectar source. So not only will it draw the Monarchs for nectar and hosting, it is a general butterfly magnet.
As its name suggests, Swamp milkweed is most often found growing in rich moist areas like marshes or near streams in its native setting. It is tolerant of wet clay soils and areas without good drainage. But, once established, it will do quite well in average gardens. Keep it well watered until it is established then water it as you would for any of your plants that require average-moist garden conditions. Swamp milkweed will grow in full sun or part shade.
Asclepias curassavica Tropical Milkweed
Asclepias curassavica AKA Tropical Milkweed, Bloodflower, Scarlet Milkweed, and Mexican Butterfly Weed. There are many other kinds of milkweed but this milkweed is one of the Monarchs favorite host plants.
Tropical milkweed is a perennial only in zones 8-11. It is originally from South America but has naturalized in our tropical zones. Elsewhere in the US and Canada it is grown as an annual because it is a fast grower and flowers all summer and into the fall.
Asclepias curassavica prefers full sun but can handle a little shade. They can grow from 2-4 feet tall depending on conditions. You will get the best performance if planted in full sun and moist well-drained soil. However, it can also tolerate some dryness once established.
Tropical milkweed can also be planted in containers and even kept indoors over winter if you have a bright sunny place for it. It will remain evergreen all winter indoors.
If you live in zones 9-11 where it stays green all winter, PLEASE cut it back EVERY time caterpillars have eaten it so new growth will form. You would basically be trimming down bare stalks that have been stripped of leaves anyway. Monarchs can get a parasite called OE and this parasite can survive on the stalks and leaves of any milkweed that does not naturally die back..
This is not an issue in areas where Tropical milkweed (or any other milkweed for that matter) does not stay green all winter.
Asclepias curassavica is a host plant for two butterflies, the Monarch butterfly and the Queen butterfly. The Monarch Butterfly can be found all around the US and into Canada. The Queen butterfly is found in Florida, our southwestern states, and down into Mexico.
When using Tropical milkweed to raise Monarchs indoors, you can simply break some branches off and put them in a container with the caterpillar. The leaves will stay good for about 24 hours in water. (Not that the leaves will last that long before being eaten!). You can also keep the leaves good for several days by putting them in a bag in the refrigerator.
Tips For Transplanting You Tropical Milkweed: If you bought our Tropical Milkweed, chances are it came in a container with 8-10 plants in it. Your plants have been “pinched back” 2-3 times before you receive them unless you purchased 1-2″ seedlings. This “pinching back” is simply cutting off or pinching off with 2 fingers the top set of 2 leaves of each stem or branch. This encourages new growth and promotes branches to split into 2 new branches. It may seem like you are wasting perfectly good leaves but believe me, you will reap the rewards in a fuller plant with maximum leaves.
The pictures below show us transplanting Tropical Milkweed. It is a very tough plant and extremely hard to kill. Take the container with the bundles of plants and gently shake it out sideways on to a tray with sides. The plants will probably separate themselves but if not, gently hold the base of the individual plants and pull apart to separate roots. Do not worry if some roots break off. We actually trim them each time they are transplanted. If roots are dry, put some water in the tray (reason for the sides on the tray). try to keep the roots somewhat moist. Once separated and planted like the examples below, water them generously and keep them out of the sun for a day. Then, once they perk up, get em in full sun and keep them watered. With a little luck, the Monarchs will find them.
Asclepias physocarpa (Gomphocarpus physocarpus) Swan Milkweed, Bishops Balls
Asclepias physocarpa (Gomphocarpus physocarpus) milkweed has several common names like Swan Milkweed, Balloon Milkweed, and Family Jewels. This is a somewhat unique milkweed and is one of the more favored host plant of the Monarch butterflies.
The terminology for this plant is a little confusing. It is a native milkweed of South Africa and in 2001 its name was changed from Asclepias physocarpa to Gomphocarpus physocarpus to reflect that it is in the family of African milkweeds. Now its true scientific name is Gomphocarpus physocarpus but many people still know it and refer to it as Asclepias physocarpa.
The other source of confusion is that it is very similar in appearance to Asclepias fruticosa (which has also been renamed to Gomphocarpus fruticosus). The difference is that G. fruticosus is a smaller plant than G. physocarpus and the seed pod is shaped a little different.
G. physocarpus has a seed pod that is more rounded and thus became known as “Balloon plant”. Now the two common names of “Swan Milkweed” and “Balloon Milkweed” are interchanged between both species.
Since the Balloon plant is native to South Africa, it is only a perennial in USDA Zones 8-10. In the cooler zones it is grown as an annual. It is fast growing but gets large so this is one you may want to start indoors before the last frost or buy an already growing plant. This milkweed will get about 4-6 feet tall and about 3 feet wide.
Balloon plant milkweed likes full sun and will grow in dry to medium moist (prefers medium moist) soil with good drainage. It will also grow well in large containers.