Monarch Butterflies Eat and Thrive on Milkweed

Creating habitat for monarch butterflies, one garden at a time...

Growing Milkweed

Please carefully read the front label of each of your milkweed seed packets. For milkweed seeds that require cold moist stratification, start with "Cold Moist Stratification Instructions". If your milkweed seeds do not require cold moist stratification, please skip to "Planting Your Milkweed Seeds".

Cold Moist Stratification Instructions

Many species of milkweed have a dormancy built into the seeds which prevents them from germinating. In nature this dormancy protects seeds from germinating as soon as they settle into the soil in the fall. Cold moist stratification naturally occurs over the winter as several months of rain/snow and cold temperatures prepare the seeds for germination in the spring.

There are two options for cold moist stratification:

Option 1 - The best method for breaking dormancy is to plant the seeds outdoors in November. This gives the seeds the required exposure to moisture and cold temperatures. Once the temperature is warm enough in the spring, the seeds will germinate.

Option 2 - The following process will break dormancy in milkweed seeds if you are not able to plant the seeds outdoors during the month of November.

1. Place seeds in a plastic Ziploc bag. We recommend that you label the bag with the date and name of the milkweed species.
2. Place 1/4 cup of horticultural sand, 1/4 teaspoon of hot water, and your milkweed seeds into the bag. Then seal the bag and mix the contents well.
3. Place bag in the refrigerator for 6 weeks and then plant. If outdoor temperatures are still below freezing, keep the seeds in the refrigerator and plant once the danger of nighttime freezing temperatures has past.

We have prepared the following video tutorial to demonstrate "Option 2" of cold moist stratification.

Planting Your Milkweed Seeds

We recommend planting your milkweed seeds directly outdoors in the spring. Before planting it is important that you wait until the danger of nighttime freezing temperatures has past. Each seed packet will cover a 2' x 2' area and you should pick an area in your garden with the appropriate sun exposure. All species of milkweed require full sun, except the following two species which require morning sun and filtered afternoon shade: Asclepias exaltata, Asclepias purpurascens.

Once you have selected an area for planting, loosen the surface of the soil, and then level the surface. Level soil will ensure that the seeds are not washed away when you water. Evenly distribute the seeds over the 2' x 2' area and then cover the seeds with 1/8" of soil. Lightly water the seeds for 30 seconds. It's important that the soil remains moist, not wet. Check the soil daily and only apply water if the soil is going dry.

Preventable Issues

If you have planted seeds directly outdoors in the past and have had trouble, there are two issues to be aware of. The first issue is that rodents, such as mice and squirrels, find milkweed seeds to be tasty treats. It is not common, but rodents can eat the seeds after you have planted them. The second issue is that milkweed seeds can be washed away during heavy rains or as snow melts. To avoid these issues, we have created the following video tutorial to demonstrate how to start your milkweed seeds indoors. You can also use this method if you want to get a head start on spring planting.

With this method, 50% of the seeds have germinated in only 7 days.

After 14 days, 90% of the seeds germinated in the seed tray shown in the above video.

Further Care

Once your seeds have germinated it is important to keep the soil moist until your milkweed plants have reached a height of 6". Again, be sure that the soil remains moist, not wet. Check the soil daily and only apply water if the soil is going dry.

Now that your plants have grown 6" tall, the root system will have reached a depth that will require less watering. These plants should be watered once a week and during hot weather can be watered more frequently. It is important to allow the soil to go nearly dry between each watering. It is recommended to fertilize your milkweed plants once a month with a diluted amount of a general purpose fertilizer.

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