To address the critical shortage of plant material, the Desert Botanical Garden (the Garden) initiated a mass propagation effort and public campaign in January 2016 to promote native southwest milkweeds, called the Great Milkweed Grow Out. The Great Milkweed Grow Out is a multi-pronged effort to grow and distribute appropriate host and nectar plants for the conservation of monarch butterflies, build seed supplies and engage and support the broader community, schools, businesses, and land management agencies in monarch conservation.
As part of the Great Milkweed Grow Out, the Garden is propagating 5,000 new milkweed plants in 2016 by partnering with a local community greenhouse and will be collecting 400,000 seeds from the wild around the state with support from the Bureau of Land Management (BLM) Seeds of Success program. The second phase of the plan is to use some of the milkweeds propagated this year for seed amplification. In addition, a field experiment will be performed during 2016-17 that will help determine hostplant suitability, phenology, and pollinator abundance and diversity in the region.
The field experiment during 2016-17 will generate:
- Seeds - Based on previous seed collections from milkweeds planted in the Garden's living collection, they expect to be able to collect at least 300,000 seeds from 8 research plots during the year, and many more in following years. They have already collected approximately 10,000 seeds in the last 8 months. The seeds will then be used for further seedling propagation for habitat enhancement and for distribution to the public for monarch conservation, creating even more momentum.
- Data on lepidopteran preference - The Garden has been doing research on monarch oviposition, but would like to collect similar data in nature. Their current data show clear preferences by female monarchs to lay eggs on Arizona milkweed (A. angustifolia) in a captive setting, but this year the project will expand to see if this carries true in natural settings as well. Data will also be gathered for queen butterflies and larvae, to see if host plant preference differs between the two species.
- Data on phenology - Different native milkweed species may have different flowering times, so the Garden will collect data regarding elevation and conditions that will inform future seed collection. Based on previous observations on A. subulata and A. angustifolia, they expect there will be two flowering seasons, fall and spring, corresponding to approximately March through May and September through November.
- Data on pollinators attracted - New milkweed habitat has the potential to attract many other beneficial animals, and provide resources for these animals. The Garden will collect data on how their milkweed patches serve other pollinators, and if this varies between milkweed species and across each season.
- Data on conditions required for raising native milkweed taxa that will benefit future habitat projects. The garden will collect data on the best growing conditions for milkweed which will be taken into consideration for resotation projects.