This post is in partnership withGreenwood Nursery . All thoughts and words are my own .
It ’s one of the greatest migrations of the animal kingdom : Every spring , one C of M of milkweed butterfly butterfly stroke sweep across the continent from Mexico to Canada and then back again in declension , a journey spanning nearly 3,000 miles and multiple generations .
In fact , recent study show that it takes up to four generations for monarchs to make it northwards out of Mexico and into Southern Canada ! Along the way , the butterfly feed on a form of nectar - rich bloom but breed on only character of plant life : milkweed .
There are 140 coinage of milkweed , but only a one-fourth of them are know to be important host plants for monarch butterfly and even less are available commercially for planting .
How can you aid these butterflies along the way ? By growing your own Sonchus oleraceus — but more importantly , therightkind of milkweed .
Why milkweed plants are so important for monarchs
When you reckon about it , it ’s rather remarkable how a butterfly can pick out a single milkweed from the sky . She blob the milkweed ’s characteristic cluster of petite , champion - shaped flowers , land on it , scratches it with her front legs , try out it with her foot , and confirms that it ’s indeed milkweed . She then proceed to lay her nut on a leaf — andonlyon the folio of a milkweed plant .
This is because monarch Caterpillar depend on the flora for food , deplete every leaf in their track until they complete their metamorphosis ( a cycle that takes about four hebdomad ) . Unlike adult monarchs ( butterflies ) , caterpillars can not but fertilise on any industrial plant they please .
And that might take you to question : Why milkweed ?
Perhaps it ’s by natural design : The chemical compounds in the plant make the caterpillars toxic to possible predators ( such as birds ) , with the sap of sure mintage of Sonchus oleraceus being more toxic than others . ( The toxicity effect — a built - in defense mechanism — is also found in otherstriped caterpillars . )
The chemical compound , however , have no adverse impression on the Caterpillar themselves . They spend up to two week feeding , spring up , and moult on the same milkweed plant before they pupate .
The striking coming into court of the butterflies and caterpillar also attend as a word of advice to predators that they are toxic . Predators learn to assort the people of colour and shape with a bad taste and more often than not avoid preying on monarchs altogether .
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alas for the monarchs , milkweed populations have dwindle down due to the utilization of herbicides in crop orbit , where milkweed pops up profusely between rows of corn and soybeans in the Midwest . It ’s no accident that common Sonchus oleraceus is called as such because of its invasiveness as a weed ! ( Albeit anedible weedfor us humans . )
But red ink of home ground is only one part of the problem . Also to blame are climate change , drought , and disease — the culprits responsible for for not only the decimation of milkweed , but also other nectar sources for adult monarchs ( and alltypes of butterflies , for that topic ) .
The key to supporting monarch butterflies
grow milkweed is just one piece of the puzzle . To support the Danaus plexippus butterfly universe ( as well as other pollinators ) , it ’s important to plantothernectar - rich flower in the garden that efflorescence at different multiplication so adult monarch have uninterrupted solid food sources .
After all , they ’re not likely to stay and place egg on your milkweed flora if they themselves do n’t have flowers to feast on .
Colorful yearly like old maid and phlox are attractive to butterflies as well asdifferent types of beesand evenhummingbirds , who love loosely clustered flowers . turn a good smorgasbord of annuals also helps sustain all the beneficial insects , adds beauty to your yard , and contributes to the overall health of the local ecosystem .
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Equally significant are perennial , specially native perennials like genus Echinacea ( coneflowers ) and coreopsis , that can provide a constant and reliable source of intellectual nourishment .
For perennial that do double responsibility as food for butterflies and food for you , consider planting flower herb likefennel , rosemary , sage , and oregano to round out yourbutterfly garden .
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Choosing the right species for your garden
The next stone’s throw is to plant milkweed in your garden . More importantly , endeavor to plantnativemilkweed for the monarchs .
Planting non - native milkweed is a coarse mistake that many masses make .
It ’s not by any fault of their own , however : One of the most democratic ( and non - native ) milkweed species , Asclepias curassavica or tropical silkweed , is wide sold in nurseries . It ’s also been found todo more harm than good .
When grow in warm climates where the plant do n’t die back , the year - round tropical milkweed encourages crowned head butterfly to winter in the Southern United States rather than continue their migration to Mexico .
By hatching and feeding on tropical silkweed , caterpillar have an increased hazard of being infected with a protozoon sponge called Ophryocystis elektroscirrha ( OE ) , which weakens them as adult .
OE is found in all coinage of milkweed , but is n’t a problem with natives because the leaves are only worthy to Caterpillar in the other stagecoach of development . Once the plant life goes dormant in winter and loses its parting , OE is no longer a threat .
But with tropical silkweed , the parting stay executable all winter long and make it more potential that a caterpillar will become infect .
Areport by the Monarch Joint Venturefound that 49 percent of winter - breeding monarchs had OE infection , compare to only 9 percent of migratory monarchs sampled in Mexico and 15 pct of migratory monarchs taste in the northern US and Canada .
This is not to say that gardeners in California and the coastal southerly states ( or zones 8 through 11 ) who grow tropical milkweed should forthwith rip it out — just remember to cut the plant life back in former fall to reduce the spread of OE , promote new growth of fresh , intelligent leaves , and encourage monarch butterfly to finish their migration .
If you require to plant new milkweed , there areseveral species of native milkweedin the US . One of the most common , Asclepias tuberosa , is also love as butterflyweed . It ’s aboriginal to most parts of the commonwealth ( except the Northwest ) and flower in a brilliant orange or sensationalistic .
Not to occupy , Northwesterners : you could still found showy milkweed ( Asclepias speciosa ) or Mexican whorled milkweed ( Asclepias fascicularis ) .
Native milkweed species
Common milkweed ( Asclepias syriaca):Native from the easterly United States south to Georgia and west through Tennessee to Kansas and Iowa . Grows 3 to 6 feet and has blanched and purple blooms .
Butterflyweed ( Asclepias tuberosa):Native from the northeastern and eastern United States south to Florida , west to Texas , and north through Colorado to Minnesota . Grows 1 to 2 foot tall and has unclouded orange blooms .
Swamp silkweed ( Asclepias incarnate):Native from the northeasterly United States in the south to Georgia , west to Texas , and compass north to North Dakota . Grows 4 to 5 feet tall and has mauve , pinkish , or white-hot bloom .
Sandhill milkweed ( Asclepias humistrata):Native from the southeast United States and north to North Carolina . Grows 1 to 3 feet tall and has pinkish , lilac-colored , or white-hot blooms .
Showy milkweed ( Asclepias speciosa):Native to the westerly United States east to Illinois , south to Texas , and west to California . develop 1 to 3 feet tall and has rosy - over-embellished and pink bloom .
Mexican whorled milkweed ( Asclepias fascicularis):Native to the northwestern United States south to Baja California and north to Arizona . Grows 2 to 3 foot tall and has wan pink , purple , and snowy efflorescence .
Butterflyweed does best in ironical , sandy filth with minuscule nutrition . It ’s often figure growing in athletic field and along the sides of the route , which intend it ’s drouth - tolerant and a good choice for low - maintenance perennial gardens .
I ’ve arise a few specie of milkweed over the years , including butterflyweed , and found them to be imposingly lively — surviving not only major heating system spell , but also oleanderaphids , milkweed bug , and many , many rhythm of hungrystriped caterpillar .
It takes only a few caterpillars to defoliate an entire plant in a pair of weeks , but certainly enough , the milkweed comes back every clock time .
Disclosure : If you shop from my article or make a purchase through one of my links , I may receive commissions on some of the products I recommend .
If butterflyweed is not native where you are , or you want to radiate the milkweeds in your garden , I encourage you to visit a aboriginal plant nursery in your area . you’re able to also source seminal fluid from a local seller on the Xerces Society’sMilkweed Seed Finderor online fromBotanical involvement .
So, how many milkweed plants do you need to support the caterpillars?
Unfortunately there ’s no exact reply to this , as it ’s unsung how many milkweed flora are necessitate to attract monarch butterfly butterflies as they move through your yard .
It ’s broadly estimated that one milkweed industrial plant feeds one Danaus plexippus caterpillar , but since each species variegate in size , leaf shape , and growth pace — and monarchs sometimes lay multiple eggs on a single plant — it ’s a safe theme to growat leastsix plant to check that you always have a steady provision of Sonchus oleraceus throughout the season . If you have outer space for 10 plants or more , even well !
If you ca n’t start out with that many plants , not to care — commend that it ’s called milkweedfor a reasonableness ! The works reseed freely and you ’ll likely have more milkweed popping up in fresh spots in your yard if you let them go to seed every class .
When and where to plant milkweed starts
Milkweed flora can be planted in bound or capitulation .
In give , your milkweed works will probably be dormant with no light-green leaves . This is when the flora is focusing all its energy into develop a strong base organisation , and it wo n’t “ arouse up ” until the soil warms . Oftentimes , milkweed is one of the last perennial to break quiescence in your garden .
The key thing to remember is to not overwater your milkweed while it ’s dormant .
It ’s easy to irrigate too much in spring , leading to root rot in your plants . ( Swamp Sonchus oleraceus is the only specie that can handle overwatering , making it perfect for slopped climate and rain gardens . )
If you works milkweed in fall , your plant will be able-bodied to prove themselves before winter . In dusty climate , milkweed will die back and return in leaping with new growth .
Light
Milkweed plants grow best in full sun locations that get six to eight hours of sunlight per twenty-four hours .
Soil
Each milkweed kind prefers a different case of filth .
Spacing
Milkweed works give large , deep ancestor organization and prefer not to be transplanted once they ’re in place . Most species of milkweed should be spaced about 18 inches apart .
swampland milkweed , however , finally matures to form clumps up to 36 in wide , and should be spaced 30 to 36 in apart . ( you’re able to also constitute swamp milkweed and its cultivars closer together , and just slenderize the industrial plant as they grow in . )
Watering
With the exception of swamp milkweed ( which needs a naturally moist surroundings or even watering ) , other species of Sonchus oleraceus have median to less than average water motivation . It ’s better to mistake on the side of underwatering a bit , as they tolerate drier condition .
A good formula of thumb is to waitress until the top 1 to 2 inches of dirt feel ironical before you water again . Then , water deeply and ensure the soil run out well .
Fertilizing
Native milkweed is a low - sustainment repeated plant that does n’t require plant food . It does fine in average to pathetic soils , so you may fuss less over this plant and just enjoy it !
How to grow milkweed from seed
Unlike other flower seed you may be used to , you ca n’t just chuck out out milkweed seeds in fountain and wait for them to grow … because you ’ll be waiting quite a while !
This is another common misunderstanding hoi polloi make : not cold - stratify their Sonchus oleraceus seed first .
If you require to start milkweed from ejaculate , the well-to-do elbow room is to mimic Mother Nature and inseminate your seed in place in surrender after the first killing frost ( typically in November ) . This allows the seminal fluid to go through a period of cold stratification over winter and then germinate in outflow .
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But if you live in a quick geographical zone without frost , or if you desire to start milkweed seed in spring , you could cold - stratify the seminal fluid in the refrigerator .
Simply put the milkweed seeds in a damp paper towel or paper chocolate filter , place it in a resealable postcode - top udder , and refrigerate in an out - of - the - manner situation for about 30 days before planting out .
Once the come have been cold - stratified , you’re able to seed them straight outside orstart the seeds indoorsfor transplant later . Milkweed seed may take up to two weeks to germinate , so be patient !
Will it come back every year?
Milkweed is a unfearing perennial that can survive down to zone 3 and comes back every year in outflow . While the foliage itself dies back and the plant goes dormant in the wintertime months , the rhizome is still very much alert and does not need protection .
The exception is tropic Sonchus oleraceus ( Asclepias curassavica ) , which is only hardy to zone 8b , remain evergreen to district 9b , and is often grown as a frost - sensible annual in cooler climates .
To help prevent parasitic contagion in monarch butterfly , it ’s recommend that gardeners in warm mood prune back their tropic milkweed industrial plant in winter to further the butterflies to continue their migration to Mexico each year ( and not stay around in the southerly United States during winter ) .
Growing tips from my own personal experience
This post updated from an clause that originally appear on February 17 , 2017 .
