Thursday, May 14, 2020
Many gardeners in Florida (and throughout North America) would like to provide more native milkweeds for monarch butterflies. Milkweeds serve as the host plant for monarchs (plus queen and soldier butterflies), meaning the butterflies lay their eggs on the milkweed. Caterpillars hatch from the eggs and eat the milkweed leaves (and sometimes the flower buds and seed pods, if they are still hungry). Once the caterpillar eats enough, it turns into a chrysalis and metamorphoses into a butterfly.
There are 21 species of milkweed that are native to Florida, meaning these milkweeds naturally occur in Florida’s ecosystems. These native milkweeds have coexisted with Florida’s butterfly populations for a very long time. As more of our lands are converted to human uses, it’s beneficial to butterflies (and other wildlife) for people to replace as many native plants as possible in our gardens and landscaping.
An initial obstacle Florida gardeners face is finding native milkweed to purchase. Typical garden centers are most likely to carry scarlet milkweed (Asclepias curassavica), a species that does not naturally occur in Florida and may have detrimental effects on Florida’s native ecosystems and monarch butterfly populations (read more from University of Florida IFAS Extension). If you are lucky to have a native plant nursery near you, they may have a few species of milkweed in stock during certain times of the year. Another option is to grow your milkweed from seed at home.
The Florida Wildflower Growers Cooperative is an online source for native wildflower seed packets. Species availability changes with the seasons, so keep checking back for more variety. I was able to purchase seed packets of pink swamp milkweed in late December 2019, planted the seeds in early January 2020, and transplanted the seedlings in late March 2020. (Note: Native wildflower seeds tend to lose viability relatively quickly, so plant your seeds shortly after receiving your packets.)
Pink swamp milkweed (Asclepias incarnata) naturally occurs in wet prairies and swamp edges, habitats that can be found locally in places like Big Cypress National Preserve and Corkscrew Swamp Sanctuary. Although swampy in nature, this milkweed can do well in garden settings with moist soil and full sun. As you may have guessed, this plant produces flowers in a lovely shade of pink. What may surprise you is the cinnamon-like aroma of the flowers.
Safety note: Milkweed plants contain toxins. Caterpillars accumulate these toxins while eating the leaves. The toxins make the caterpillars and adult butterflies taste bad and protect them from predators. If a milkweed stem is broken, a milky sap will ooze out. Avoid getting milkweed sap on your skin. If you do get the sap on your skin, avoid touching your face or eating until you can wash your skin with soap and water. Take care around pets or children. Anyone with known plant or latex allergies should take extra precautions.
Ready to sow your seeds? Fill a seed tray with potting soil. Make a small depression in the soil in each compartment, just big enough to place 1-2 seeds. Repeat until you run out of compartments or seeds. Sprinkle more potting soil on top to just cover the seeds. Gently water, and place in full sun. Water seed tray daily (early morning recommended). Look for seedlings to start sprouting within a couple of weeks. Continue watering seed tray daily or more often if seedlings are wilting in the heat of the day.
Ready to transplant your seedlings? Follow the steps below to get your native milkweed plants in the ground! (Note: I transplanted my seedlings when they were about 4-5 inches tall. One way to check if your seedlings are ready to transplant is to inspect the openings at the bottom of the seed tray. If you see roots sticking out, your plants are ready for more room to grow.)
Step 1: Choose your planting site & gather your tools
All you need to start planting are your seedlings in the seed tray and a small digging tool. Later you will need a watering can or hose. You can wear gloves if you don’t like getting your hands dirty (or if you are worried about contacting the milky sap). I recently created a native plant bed in the front yard, so I chose to add my milkweed seedlings to it.
Step 2: Dig a small hole
I used a narrow soil knife to dig holes for my seedlings. The length and width of the soil knife allowed me to easily dig narrow holes the perfect depth for my seedling’s roots (about 4 inches).
Step 3: Poke the seedling out of the tray
I used my finger to poke the seedling (including roots and soil) out of the tray. It’s best to do this when the soil is moderately dry so the soil and roots pop out together.
Step 4: Place the seedling in the hole
Make sure the base of the stem matches up with the level of the ground. If your seedling sits too deep in the hole, simply put some of the soil back in the hole. If your seedling sits too high, make your hole a bit deeper.
Step 5: Fill the hole with soil
Use your digging tool or your hands to push your excavated soil back into the hole surrounding your seedling. Add soil until there are no gaps. Gently push down on the soil all around your seedling so it is snug in the ground.
Step 6: Water the seedling
Get your watering can, and fill it up with water (or turn on your hose). Gently water the seedling. Watering in plants like this allows the roots to absorb water right away and helps the plant overcome the temporary stress of transplanting. If you are working in sandy soil, wait a minute for the water to seep into the ground before watering some more.
Repeat Steps 1-6
Repeat previous steps until all your milkweed seedlings are planted. I placed my seedlings about 1 foot apart from each other. Given time and reasonable respite from caterpillars, pink swamp milkweed can reach 2-3 feet tall. Water your newly planted milkweeds daily for at least two weeks during the dry season (October-May) until the roots are established. If you transplant between June and September, the daily rains should take care of watering for you.
Optional: Add mulch. Natural mulches, like pine needles, help suppress weeds that could quickly outcompete the seedlings. Other benefits of this natural mulch include shading the soil from the heat of the sun, minimizing water loss, and providing good air circulation. Plus, it makes sense for me to use pine needles since my yard is full of pine trees!
Enjoy watching your native milkweeds grow. It shouldn’t take long for monarch butterflies (and possibly queen and soldier butterflies) to find their host plants. Next, you will be looking for the caterpillars devouring the leaves. Remember, milkweeds have a long history with monarchs. Even if the caterpillars eat all the leaves, the milkweed is likely to flush back out with time. Thanks for planting native and providing for wildlife!
About the Author
Andee Naccarato is the Horticulture Volunteer Coordinator at Naples Botanical Garden. She also serves as President for the Naples Chapter of the Florida Native Plant Society. One of Andee’s favorite experiences is wading through cypress wetlands during rainy season.