Our Experience Growing a Large Patch of Milkweed with Occultation

Starting in the fall of 2023, we experimented with a new way to grow milkweed.  Since milkweed emerges from the ground later than many other plants, small milkweed plants can easily get smothered out by grass and weeds.  We don’t have a lot of time and energy for weeding and we have decided not to use herbicides, so we decided to try occultation (tarping) to control weeds in and around our milkweed patch.  The idea is to keep the area under a tarp while the milkweed is dormant so the weeds never get a head start on the milkweed and then we only need to weed the area for the five months that the milkweed is green.  

We used an area inside our deer fence which was formerly used to grow vegetables so it was relatively clear of weeds and grass.  The deer fence was helpful because we have seen that deer do eat milkweed.  In this area we planted 6 rows of milkweed, about 40 feet per row, with drip tape along each row.  One row was planted with roots dug up from milkweed in our lawn (cut into 3-4 inch sections and planted 18 inches apart), and the other 5 rows were planted with seeds.  Then we covered the whole area with a large black tarp from Farm Plastic Supply and held it down with cinder blocks on the edges and between the rows.  Our plan was to remove the tarp when the milkweed started to come up in April.  Unfortunately, the black tarp warmed the soil and made the milkweed come up sooner than expected, so by the time we removed the tarp on April 17 (2024), the seeds had already sprouted into long spindly seedlings which mostly died in the ensuing dry winds that month (even though we watered them.)  Only the plants which sprouted from the roots survived.

But we didn’t give up.  We replanted 5 rows of milkweed seeds in mid-May of 2024 and those grew well with our irrigation and weed control (hand-weeding and hoeing).  One row was Narrow-Leaf Milkweed and the rest was Showy Milkweed.  The Narrow-Leaf Milkweed even bloomed!  On Dec 23rd of 2024, we covered the whole area with a tarp again, but it was a white tarp this time.  In early April 2025, we began checking under the tarp to look for milkweed sprouts.  On April 13 we found them, so we pulled off the tarp.  We were surprised to see that the rows grown from the May seeding have sprouted, but the row grown from the planted roots has not yet emerged.  Also the Narrow-Leaf row is not up yet.  The tallest spouts were in the middle of the area and they were about 4 inches tall.

We could not find information about whether or not we should thin the plants that came up from seeds, so we never did.  Time will tell on that.  Our plan is to continue covering the milkweed patch with a tarp every winter and removing it in early April.