I'm not certain all milkweed grows taproots. I know for certain Butterfly Weed (Asclepias tuberosa) does.

To try and answer your question, I'd suggest at least 16" deep pots for milkweed with a taproot. The only perennial milkweed I've attempted to grow long term in a pot is Common Milkweed (Asclepias syriaca) and to my knowledge, it doesn't grow a taproot but instead, creates horizontal roots that will put up new shoots of growth, sometimes several feet from mama plant.

What variety of milkweed are you planning on growing?

Mary

They did not identify the species so I'll ask them. I thought it was the Common Milkweed, Asclepias syriaca.

Thank you for your nicely detailed response to my questions.

Joseph

Joseph,

If common milkweed, it is certainly doable and in my opinion, would be the best choice for a perennial milkweed because of the first year growth. Other perennial milkweed I've grown from seed have very little top growth the first year as they appear to concentrate on developing their root growth in the first year. Common milkweed, in my experience, puts on more top growth the first year and because the leaf size is about the largest of the native milkweeds, it will provide more food per plant, for the monarch cats. It would be unusual to see blooms on any first year perennial milkweed.

Tropical Milkweed (Asclepias curassavica) is a milkweed grown by many butterfly gardeners as an annual because it grows fast, blooms the first year and regenerates fast when stems and or leaves are clipped to feed monarch cats. If you would like to try some of this type of milkweed, try the Adopt a Milkweed Newbie Thread on the Seed Exchange forum.

http://forums2.gardenweb.com/forums/load/exseed/msg031854574504.html?7

Thank you for growing milkweed for the Monarchs.

Mary

Here is a link that might be useful: my Common Milkweed growing in a pot

Nice photos, Mary!

I have grown swamp, common, tropical successfully in containers. I grew tropical in the buckets from home depot. Swamp mw was a mix of those buckets (I dont recommend) and those big tubs with rope handles. There were others in between that worked well too. Water suckers is all I can say. Watering several times a day. Thanks fully I can put them in the ground this year with my new garden plot. :)

The common did ok too in the big tubs. The butterfly weed certainly did not like it. It died weeks after putting them in there. But I am still a new gardener so I'm pretty sure it was my fault

Oh I've had tropical in hanging baskets. Lol wont do it again though. Too tall!
Good luck.

I have grown swamp, common, tropical successfully in containers. I grew tropical in the buckets from home depot. Swamp mw was a mix of those buckets (I dont recommend) and those big tubs with rope handles. There were others in between that worked well too. Water suckers is all I can say. Watering several times a day. Thanks fully I can put them in the ground this year with my new garden plot. :)

The common did ok too in the big tubs. The butterfly weed certainly did not like it. It died weeks after putting them in there. But I am still a new gardener so I'm pretty sure it was my fault

Oh I've had tropical in hanging baskets. Lol wont do it again though. Too tall!
Good luck.

Swamp and tropical are the best for containers. My common and butterfly weed doesn't come back on a consistent basis. But, I am in zone 7 usually, where most perennials die back during the winter.

I purchased an Asciepia Incarnata (swamp milkweed) plant from one of my local nurseries in Michigan last year. I transplanted into a bigger pot for root growth. It flowered and had 1 seed pod that I let crack open a little. I picked the pod and put into a paper bag and refrigerated over the winter so I could start additional plants. The question I have is, I brought my plant indoors for the winter and put in basement in a bucket of water so it wouldn't die over the winter. How do I get the plant to sprout and grow again so I can help the low Monarch population? The stalks look grey with no leaves on them. I am worried that I may have killed the plant and should have left it outside over the winter with the snow. Any help or advice would be appreciated.

It probably is dead. Have you checked the roots? I'd work on starting the seeds to grow more plants. Asclepias incarnata will adapt to regular garden soil. It may grow in a wet area, but does not require constant wet conditions.

Nadine,
Your A. Incarnata probably would have been fine outdoors all winter. I'd recommend planting it somewhere outside in the ground, if you have space, and see if it comes back. It definitely won't do much without soil and sun. It may be dead, but I think it's worth trying to plant it.

Martha

I now have put my Asciepia Incarnata (swamp milkweed) into even bigger pots (1 gallon size) and was able to see the roots and they looked like they might grow. I was very careful not to disturb the roots and added lots more soil too. I have now put them outside on the deck in the bigger deeper pots. I did not know they could be left outside over the winter and would grow again in spring (perennial). Sounds like they somewhat are like caring for mums, catmint, and sedium. I did scatter the seeds from fall on dirt and put a very light layer of soil on top and watered. Hopefully the seeds will sprout too. For my care and future information, so I won't kill additional milkweed, After the plants bloom, get the pods and after the pods break open, when can the stems with no leaves be cut down and how far down should the stems be cut so I won't kill or damage the plant from coming up in the spring? Do they have any real outside temperature criteria for trimming? I can't seem to find a good website (other than Gardenweb) to get great information on caring for milkweed. Thanks in advance for any further information that can be provided.

Once the leaves are gone, the plant is no longer actively growing or storing nutrients, so you could cut the stems back to the ground, or keep an inch or two so you know where the plants are.

Martha

I'm growing Tropical Milkweed in containers to use if I'm lucky enough to get any Monarch caterpillars. They sprouted a few weeks ago, so today I transplanted them into individual pots. None of them have any second leaves yet, but each has a tap root that almost reaches the bottom of their new pots. I guess I'll be transplanting again into something much deeper. Maybe a Pringles canister. Lol.

Martha

I usually leave any cutting back to late spring (May) when I tidy up my front garden. Many butterfly species winter over in our gardens on those very stems. The stems do not need to be cut back at all. The only reason you would want to cut them back is to tidy up your garden.

A friend in Ohio wrote this about transplanting milkweeds:
" Fall is an ideal time for planting. If you have milkweeds to share, or plants needing to be rescued, fall is a great time to transplant milkweeds. Milkweeds such as butterflyweed (A. tuberosa), swamp milkweed (A. incarnata) and common milkweed (A. syriaca) can be transplanted in the fall, after they are done producing seed and have begun to senesce (die back) for the winter.
Swamp milkweed is probably the easiest milkweed species to transplant. The roots of swamp milkweed form a ball, similar in appearance to the head of an old-fashioned mop. Dig 1-2 feet deep and 1-2 feet wide around the base of the plant, depending on its size. A good rule of thumb is to dig as wide as the crown of the plant is wide. Always, water your plants before digging them up, this will help the soil adhere to the roots, and give the plant a thorough drink before disturbing its root system. After digging up the plant, place it in a pot, bag or a bucket of water in a part shade area for a few days. This will help the plant overcome transplant stress. If you must plant it in its new home immediately, you can do so, but keep the plant well-watered for a few weeks. Choose an early morning or cloudy day to do your transplanting, to protect your new transplants from the harsh sun.
Butterflyweed is a bit more tricky to transplant. Butterflyweed transplants best in late fall or very early spring. This milkweed species has a deep taproot that is thick and knobby, reminiscent of a carrot. Again, it is important to water the plant before digging it up. Dig deep, usually 2-3 feet deep and 2-3 feet wide around the base of the plant. Place the plant in a pot, or move it to its new home immediately. You can place the transplant in a bag, but often sandy soil will fall from the roots or the taproot will break, using a pot will work best. Make sure to plant the milkweed at the same depth it was previously, to avoid rotting the taproot or exposing too much of the taproot to winter heaving. Be certain to place the plant in a site with well-drained soil, and keep it watered well for a few weeks to help it through the transplant stress.
Common milkweed can also be transplanted, but it has a very deep taproot. You will need to dig 2-3 feet deep, and 1-2 feet wide. Make sure you dig up a section of the root that includes the horizontal rhizome. The rhizome is the horizontal root that runs out like a tendril from the stalk, or ramet. When you dig up the ramet, you will need to cut the rhizome with your shovel blade, leaving a portion of the rhizome still attached on either side of the ramet. Essentially, you will be digging up a section of the root system that will look like an upside-down “T.” Digging up a “T” section of the root system will greatly increase your transplant success. After digging up the plant, place it in a pot and move it to its new home. Keep it watered well for a few weeks to help it through the transplant stress.
Milkweeds can be transplanted in early spring as well. Follow the same steps as described previously, but dig the plants up shortly after they break ground, when they are about 4-6 inches tall. Never dig up plants when they are blooming or going to seed, doing so will cause significant transplant stress and may kill the plant. Do not dig plants from the wild, and always get permission from the property owner if it is not your property! Finally, keep your transplanted milkweeds watered regularly for the first year, and then leave them on their own. They are native, after all!"

Here is a link that might be useful: Container Gardening

Just an update to my milkweed. I put a new Harbor Freight 6x8 greenhouse in the yard (actually it was a "honey" husband project to build). I am happy to say that my milkweed that I kept in the basement over the winter in a bucket of water, transplanted into bigger containers and set in the greenhouse is starting to come up about 2 inches. Yeah! Also, some of my seeds are starting to sprout and have poked through the soil. Next "husband" project is to find some cheap landscape timbers and put another flower bed on the side of the house dedicated to Monarch butterflies. Not sure when to transplant the sprouts of the new milkweed seedlings, as they only have 2 leaves on them and are doing well in the greenhouse. I probably will let them grow a bit longer in the greenhouse protection environment. Thank you "docmom" for your insight as it has been a great help. I think I do better at vegetable gardening rather than flower gardening but I am dedicated to getting better at the flower gardening. :)

Many A. curassavica, same individuals crammed together in
same 3-gal pots for third consecutive year.
You can imagine the root congestion. For that reason, water needed often.
Blazing sun all day most days; more water.

Why the torture? Because they thrive, and flower continuously.
Blatant contrast to all of the many generations of their ground-planted
source plants, and siblings. Rain-saturated ground either kills or
permanently debilitates.

Also, same arrangement in a massive pot that gets afternoon sun;
water needed occasionally.

Note that all are of the golden-flowered variety of A. c.
Red-flowered ones have not done well for long.

I grow all of my plants in containers, due to available land around my mobile home coach is limited. Here on the Left Coast I've had success with Asclepias curassavica, A. fascicularis, A. speciosa "Davis", Calotropis procera, and Gomphocarpus physocarpus. Asclepias eriocarpa didn't do well for me, it having a very long taproot, being it's a very drought tolerant native from here that must search deep for water.

I tried Asclepias incarnata several times here and up the coast in Laguna Beach, but at both sites, A. incarnata was an Oleander aphid magnet. They literally covered the whole of the plants, sucking the life out of them. The ladybugs couldn't keep up!

Large infestations start with a small group at tip of one or very few plants. It is not difficult to eradicate manually the small group. You repeat as new small groups occur from time to time.

I tried to keep up eradicating aphids on the milkweed plants, but with 20+ individuals, it became an unending chore. Besides, the population explosions were dramatic, even with judicious squishing. Eventually, I just let nature take over by letting ladybugs, lacewings, and predatory wasps cull the herds; or were they hoards...

Yes, there was a primary large spike in aphis infestation, but after a while a natural balance was set that I could live with that didn't adversely the plants still living. Besides, it was fun seeing ladybug adults and larvae scurry about the plants, finding lacewing egg clusters, and discovering empty aphid body shells that were parasitized by wasps. Also spotted a few predatory Coleopterans hunting about the milkweed leaves and stems. All-in-all, quite satisfying.