5 Steps to Planting Milkweed Seeds Indoors

3/7/2020

The Monarchs are already starting to migrate North, will you be ready for them? Unsure when the Monarchs will be coming through your area or state? Check Journey North's Migrations Map to find out!

I started cold stratifying my Butterfly Milkweed seeds at the beginning of March. 30 days have passed and they are ready to be planted!

It is worth noting that cold stratifying your seeds increases germination rates but is not absolutely necessary. The most important thing is that you get them planted. Most milkweed is a perennial in the lower 48 states so even if you are getting off to a late start, have no fear, they will come back next year and feed the next generations!

Step 1: Gather your materials

You will need:
A clean seed tray (a baking pan works well too)
Seed cells
Sterilized seed starting mix
Milkweed seeds
Water

It is best to use a designated seed starting mix because it is lighter and less dense than regular potting soil, which allows the roots to establish more easily. Milkweed is slender and doesn't need much room to grow so go ahead and plant many seeds!

Step 2: Add soil

I like to pour a heaping amount of soil mix onto the center of my seed insert and then spread it evenly with the edge of my seed packet or anything with a straight edge. I then gently tap the bottom of the seed tray on a flat surface to let the soil mix settle just a bit.

Step 3: Make holes

I like to use the eraser-end of a pencil to get ¼ in holes in my soil. It’s a convenient and consistent way to get uniform sized holes. I have also sprinkled the seeds on top of the soil and then sprinkled a layer of soil over them with success.

Step 4: Plant your seeds

Place 1-3 Milkweed seeds in each hole. Placing multiple seeds in each hole will increase your chances of getting a seedling in each cell. Then, gently push the soil mix back over your seeds.

Step 5: Water

Watering from the bottom up is the recommended method because it won’t disturb the seedlings and will also prevent over-watering. Simply pour about ½ inch of water into the tray then place the seed inserts on top. I like to use a water mister to also spray the top layer of my seed tray and then cover with a plastic lid or plastic wrap to keep the seeds moist. Remove the lid after a few days so that the seeds get air-flow and mold does not develop.

Lastly...

For 3-5 days, your seeds won't need light but a seed heating mat will help them to germinate. Once they sprout, immediately put them in a sunny window or under a grow light. If you wait too long they may get "leggy" from lack of sunlight or become moldy.

If they start to look leggy, you know that they need more light. You can plant your Milkweed outside after the danger of frost has passed. Check here to find out when the last frost date is for your region.

Plant the Milkweed and the Monarchs will come!

45 Comments

Linda

4/1/2018 04:13:58 pm

I live in South Florida. How about outside?
I am goong to plant the seeds outside tomorrow.

Save Our Monarchs

4/7/2018 02:50:43 pm

Hi Linda,
I would check your Average Last Frost dates on the Old Farmer's Almanac but they should be just fine! Plant the Milkweed and the Monarchs will come!

Trish

3/14/2019 11:46:18 am

What variety of milkweed is best for the monarchs?

Rebecca Chandler

3/14/2019 07:27:42 pm

Hi Trish!
It depends what area you live in. Native species are generally best suited for your region! Monarch larva will feed on all Milkweeds in the Asclepias genus.

Jordan

3/20/2019 11:47:41 am

I plan to plant the seeds outside. Do I need seed starter?

3/20/2019 12:50:33 pm

Hello Jordan!
Thank you for your question. If you are direct sowing then you do not need a seed starter. However, it will increase your germination rates and chance of survival if you start them inside and transplant them outside after about 2 months of growing indoors. Hope this helps!

Dana

8/20/2019 08:22:51 am

Can egg cartons (plastic or paper) be used instead of seed cells? Thank you!

Rebecca

1/31/2021 08:41:19 am

Egg cartons will absolutely work! Great idea.

Emily

8/27/2019 05:35:08 pm

What is a seed cell?

4/18/2020 10:13:54 am

Hi Emily,
Sorry for the confusion. A seed cell is simply a plastic planting container that is often used in greenhouses to start seeds in. They are also called seed trays. The seed cells are generally just an inch or two wide which allows you to start many seeds in one tray.

8/27/2019 05:38:28 pm

Do I need to use a heated seed mat to start the milkweed inside

1/31/2021 08:44:08 am

I would recommend a heated seed mat to start the seeds indoors!
What I like to do is plant the milkweed seeds in trays, place the tray with soil and milkweed seeds inside another tray and then place abouta half inch of water into the outside tray. This allows the seeds to get watered gradually and gently. Then, I place both trays onto a heated seed mat and cover both trays with a plastic lid. As soon as the seeds start to sprout, I remove the cover and place them in a well-lit area. At this point, you can remove the heated seed mat. Thanks for your question!

Peter

4/19/2022 03:07:34 pm

If you don't want to purchase a heat mat, just put the seeds in your furnace room or on a container on top of your furnace, depending on how hot it gets. For my high-efficiency furnace, putting warmth-loving seeds in baggies with damp paper towels in a cookie tin on top of my furnace works great.

Carol

3/7/2020 04:31:04 pm

Does common milkweed need heat to germinate indoors? I’ve heard that it is better to not have them on a heating mat.

1/31/2021 08:44:40 am

Yes, the heating mat will help them to germinate! Once they have germinated, you can remove the mat. Thanks!

J.T.

4/2/2020 08:12:57 am

When the milkweed is ready to be planted outside, what kind of area do they need to keep growing? Full sunlight? Can they be planted with other native flora or by themselves? Thanks! Can't wait to get started!

Jessica

4/14/2020 02:24:18 pm

They need full sunlight and room to grow. Spaced about 18-24in apart.

1/31/2021 08:46:49 am

Yes, Jessica is correct. Full sunlight and about 18 inches to grow. Some varieties of milkweed need less room. For instance, Butterfly Milkweed (Asclepias tuberosa) is a much smaller plant with less broad leaves that Asclepias syriaca so you can plant them 6-12 inches apart. Refer to the seed packet for more information or look up planting instructions for your species of milkweed. Thanks!

Ted Mattison link

4/18/2020 07:52:44 am

My podcast Wonder Outside debuts on 4/22 in a few days...can I mention you as a resource for planting milkweed? As a place people can visit for how to plant? I’m seeing it’s s but late in the season but still okay? Very last minute but would love to link to this site and mention you. Thank you! Ranger Ted

4/18/2020 10:01:11 am

Hi Ted!
We would be honored if you listed us as a resource for your podcast! Can you please post a link on how we can listen? It's still a great time to plant milkweed. In fact, most people wait until after their area's last frost but some like to get a headstart by planting them indoors. Let me know if you have any other questions.
Best,
Rebecca

Meredith

1/18/2022 05:55:53 am

Interested in your podcast on starting milkweed seeds indoors.

Bethany Farless

4/23/2020 08:21:20 am

Should you soak the seeds before putting them in the soil? If so, what's the best method of soaking?

1/31/2021 08:48:18 am

Soaking is not required. The moist paper towel will soften the seed coat over time. The cold temperature will simulate "winter" so that the seeds will wake up once they are warm again.

Joy Price

5/28/2020 01:57:12 pm

Five years ago, I ordered lots of milk weed seed packets and did a school-wide project with them. I retired that year. In cleaning out some book bags, I found a bunch of the seed packets that had never been opened. Is it possible to plant them, or should I just play Taps?

Marie Nelson

9/26/2020 08:20:02 am

Hi Joy Price! There is no reason not to at least attempt to get them to germinate. There are many variables when it comes to seed viability. Even if you only get 1 plant growing, that's more than you had. Be patient, older seeds may well take an extended period of time to germinate. Hang in there and good luck.

s Slechta link

8/29/2020 05:36:01 am

help! I have so many caterpillars they have stripped my plants, leaves can't grow fast enough. hate watching them starve , keep planting more , what do I do? North of tampa, they were here most of winter too!

1/31/2021 08:50:27 am

Hi,
I'm sorry that this happened. If you have an overpopulation of monarch caterpillars on one plant then you can go to your local plant nursery to buy more. Sometimes it's helpful to plant more milkweed than you think you will need. You can also transport your caterpillars to wild populations of milkweed if you know of any in your area. Thanks!

Russell Thomas

3/21/2021 05:35:01 pm

I have a property in a "range area" in E. WA. So several years ago I was forced to destroy this noxious weed patch (250 square ft ish) by the county extension office. I was facing fines up to $10,000. Has this law changed.

John

4/4/2021 01:55:01 pm

How do I start butterfly milkweed indoors?

Ann H Keech

4/10/2021 08:10:34 am

I've got milkweed seeds (taken off heir fluff) from last fall, out on cold porch for at least a month in envelopes and some baggies. Do I soak the seeds before starting in planters inside? Soak before planting outside mid May? Philadelphia region.

Mary Jane Bolo

4/30/2021 08:14:09 am

What temperature is required to germinate milk weed? mine wont germinate Should it be dry?

Cindy D.

10/3/2021 09:42:13 am

I'm planning to grow milkweed in my yard next year. I live in Wisconsin. I have pods drying out now. I haven't decided how to plant the seeds yet. If I plant them indoors, when is the best time to start planting?

Leslie L link

3/20/2022 07:04:53 am

Starting native SWFlorida milkweed from seed. When May I expose seeding to direct sun? They are about 2 inches now in filtered sun. May I put trays of seedlings in direct sun? Thank you

Genie Guerard

7/18/2022 04:35:24 pm

I germinated my showy milkweed seeds by clipping and keeping in bath of distilled water for 7 days on top of a seed warming mat; then today I put them into soil in small trays. QUESTION: Should I keep the plastic dome on or off? Should I keep them outdoors or indoors? Some of the seeds might have grown mold. I planted them anyway. Is that going to be problematic?

Patrick suzeau

1/11/2023 07:31:40 am

I don’t get step 3. You put seeds all over, then you make a whole with a pencil, then you put 3 seeds in the whole. That means, if I am reading you correctly, that there are more than 3 seeds in each ?

Lori Carns

3/4/2023 05:34:24 pm

It's either or. Either sprinkle the seeds on top and cover with a layer of soil OR make a hole for the seeds with an eraser.

Amy

3/5/2023 07:07:17 am

If you plant the seeds in egg cartons, how do you recommend watering? Also, how long can the plant survive in an egg carton before it needs to be transplanted? You had said to plant inside two months before planting outside. Is that still accurate?

4/2/2023 09:41:16 am

Is there a soil you recommend to start the seeds?

There is so much information out there that I am intimidated by it all.

Thanks

gutter services link

4/6/2023 11:25:05 pm

I find this post so useful. Thanks for sharing this information!

Abby

11/18/2023 11:28:16 am

What if I just plant one seed? Can I just use about a 2in by 3in pot?

Cait

2/10/2024 08:13:55 am

How many hours of grow lighting would you recommend for new indoor milkweed seedlings?

3/1/2024 10:33:53 am

I ordered 150 seeds from livemonarch.com and started growing inside 2 weeks ago. I bought trays on Amazon and bags of seed starter from Walmart. I have 1 tray on a little table by a window with a heating pad I set on medium every time I walk by and 4 trays in a bathroom closet with 24 hours of grow lights. Both seed trays are growing at the same rate. Today I am transferring to bigger planters and miracle grow soil for the ones that are about 2 inches tall. I bought both the soil and trays (7 pack with water collectors on bottom) on Amazon. I live in Central Oklahoma where milkweed grows in the wild, but I have a raised garden in my yard that will be designated for what I'm starting inside. I just want to let you know that it is possible to start seeds inside just on a heating pad by a window. I also have weekly pictures of anyone needs to see what to expect.

Helen Conroy

3/14/2024 01:06:05 pm

My milkweed seeds have all started to sprout, but some of the leaves are a light pink … some on that same stalk are green. What is the issue do you think???””

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Cindy Spearman

3/19/2025 10:15:23 am

I planted the seeds and put water in the tray and the next day the tray has no water. Should I add more water to the tray.