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• When should I plant my young milkweed plant?

  March-August is an ideal time to plant native milkweed in California. The warmer temperatures and longer days help the young plant become established.

• Where should I plant my milkweed?

  Native milkweed naturally grows in open grassland. They thrive in full sun or partial sun areas. They need at least six hours of direct sunlight a day but can benefit from some afternoon shade in the summer. Most plants in full sun will flower strongly by year 2, while plants in part shade will have less flowers.

• What kind of soil does milkweed need?

  Narrowleaf milkweed grows in every county of California so it is very adaptable and can grow in different soil types. Soil amendments are not necessary, but they also won’t harm the plant. You can amend by mixing compost into your native soil.

• How big does milkweed grow? How far apart should I install the milkweed plant?

  Between 3 to 6 feet from each other is a good distance. Narrowleaf milkweed grows approximately 3 feet wide and 3 feet tall so it’s important to give them enough space to grow while also placing them within crawling distance for monarch caterpillars.

• How much water does milkweed need?

  Since narrowleaf milkweed is native to California, it will not need much water once roots are established. You can water a young plant 2-3 times per week, giving it a total of 2-3 gallons every week. Once your milkweed is established, you can water deeply (2 gallons) once a month between November and March if there is little to no rain. During the dry season, between April and October, established milkweed only needs to be watered deeply twice a month.

• Can I plant milkweed in pots?

  Yes. While it is best to plant in the ground, it is okay to plant in pots. We recommend a 3 to 5 gallon container per plant. Containers dry out quicker and may need to be watered more frequently than in ground. Milkweed also does well in container beds if space is available.

• Why does my milkweed look like it's dying?

  Native milkweed naturally goes ‘to sleep’ during the winter. As the days get shorter, milkweed will lose its leaves and the stems will turn brown and dry. Your plant is still alive underground, make sure you don’t pull it out! At this time, you may place a flag by your plant to easily remember where it is. In the spring, it will regrow once again from its rhizome root system.

• When will my milkweed come back?

  New milkweed shoots will emerge mid to late spring. Milkweed likes warm weather; once the days get longer and temperatures consistently reach 70˚F, you should see your milkweed emerging from the ground!

• How many milkweed plants should I have?

  While there is no exact answer, we recommend having at least 5 milkweed plants, spaced 3 to 6 feet apart from one another. The more plants that you have, the better! Monarch caterpillars have vigorous appetites and can easily devour milkweed plants. Planting enough ensures that caterpillars have enough food because they can travel to nearby plants to find more!

• Do I have to water my milkweed after it goes dormant?

  It depends! If your milkweed is in the ground, it is not necessary if the winter rains are significant. If your milkweed is in pots, you should continue to water once or twice a month during dormancy because containers dry out quicker.

• What other native plants should I grow with milkweed?

  We recommend growing a diversity of native nectar plants alongside your milkweed for year-round blooms. You can also plan your garden around milkweed’s dormancy period (November-March). Use early-flowering natives like currants (Ribes), yarrow (Achillea), and bladderpod (Cleome) to help draw attention away from the empty space where milkweed has gone dormant. A few other narrowleaf milkweed companion plants include black sage (Salvia mellifera), toyon (Heteromeles), elderberry (Sambucus), and coffeeberry (Frangula). These plants like being watered twice a month during the dry season (April-October), which is the perfect watering cycle for local milkweeds as well. You can reference Xerces Society’s list of native pollinator-friendly plants for each region in the United States for more options.

• What should I do about the bugs on my milkweed?

  It is common to see bugs such as aphids, beetles, and spiders on milkweed. The yellow aphids, or oleander aphids (Aphis nerii), do not harm monarch butterflies or caterpillars directly, so there is no need to spray or attempt to remove the insect. In most cases, the aphids will appear, reproduce, and leave the plant within a few months, leaving very little damage. Black sticky soot is common to find with aphid populations but is almost never harmful to the plants or monarchs. We recommend leaving them alone and allowing beneficial predatory insects to take care of them. You can plant companion plants like native yarrow near your milkweed to attract the beneficial insects that eat oleander aphids. Please do not attempt to remove the aphids, as almost any method used may also harm monarch eggs or caterpillars. The red and black oval bugs, or large milkweed bugs (Oncopeltus fasciatus), are also common. These bugs consume milkweed sap from the seed pods but do little harm to the plant or caterpillars otherwise.

• How can I grow milkweed from seed?

  Start narrowleaf milkweed seeds late winter through spring for best results. To improve germination rates, you can prepare seeds for planting through cold stratification. To do this, store seeds in moist paper towels in a plastic bag and put them in a refrigerator for 4 weeks. Seeds can easily rot during this process, be sure to provide enough airflow. After cold stratifying, sow your milkweed seeds by scattering 3 at a time on a flat of soil 1/4-1/2 inch apart, and then cover with about 1/4 inch of soil. Place the flat in full sun and cover with thin plastic to maintain soil moisture. Most seeds will germinate in 7-10 days if the flat is kept at 75˚F. Once seedlings emerge, transplant into 2 inch containers before planting in the ground. Success in growing milkweed from seeds is often mixed; SAMO Fund distributes young narrowleaf milkweed that is grown past the seedling stage to increase the odds of successful installation.

• Should I cut my milkweed?

  Cutting back your native milkweed is not necessary, but can improve how it looks in your garden. If you’d like to prune your plant, wait until the stems are fully brown and there are no monarch eggs or caterpillars, then cut the plant back to the ground. Mark your plant with a flag to remember where it will reemerge in the spring.

• Is milkweed toxic to pets?

  Milkweed has a milky latex sap that is toxic to pets and monarch predators. However, harm to pets doesn’t occur often due to its unappealing bitter taste. If your pet is prone to eating your plants, focus on installing native nectar plants instead like California fuchsia, California buckwheat, or sticky monkey-flower.

2024 Monarchs and Milkweed Symposium