Production of Drought-adapted Intermountain Native Plants Through Low-cost, In-containers for Emerging Western Markets

Production of Drought-adapted Intermountain Native Plants Through Low-cost, In-containers for Emerging Western Markets

Summary

We completed a second study investigating production of Intermountain West native wildflowers in 2004 comparing pot-in-pot (PIP) production of 1-gallon plants to conventional aboveground production. This study was a follow up to the initial project objectives of comparing irrigation systems and growing media. We found that plants grown in the pot-in-pot system had cool root systems, lower total plant water use rates, and high rates of stomatal conductance. Related to these results, we further found that plants grown in the pot-pot system generally had higher overall growth rates, suggesting that this system could produce plants more rapidly than conventional aboveground production.

Objectives/Performance Targets

The goal of this study is to develop a model nursery production system, with an economic analysis, for drought-adapted native woody and herbaceous perennial species using an alternative in-ground container method in the rural Intermountain West (IMW) to encourage adoption by small entrepreneurs. The specific objectives of the project in 2004 are to complete the revision of the original objectives, investigating whether pot-in-pot production of IMW native perennials results in improved growth, thus more production cycles, compared with conventional aboveground container production.

Accomplishments/Milestones

1. We completed the follow-up study with a new graduate student, Guillermo Cardoso, to directly compare pot-in-pot production to conventional aboveground production. Potential nursery entrepreneurs interested in growing Intermountain native plants need this information to make an informed decision as to the most cost effective production approach. In the first year (2003) of this follow-up study we compared the conventional above-ground and pot-in-pot production systems using three wildflower species, desert 4 o’clock (Mirabilis multiflora), western columbine (Aquilegia caerulea), and palmer penstemon (Penstemon palmeri) in 1-gallon containers. Each production block consists of 49 plants with two border rows along the W, E, and N sides. The three inner treatment rows consisted of five plants arranged N-S including the southmost plant at the edge of the plot. We chose this approach to evaluate the effect of aboveground exposure on edge plants. Species were randomly assigned to a row, and each paired treatment block was replicated six times. During the first season two production cycles were run, and for each five-week production cycle the graduate student measured total plant water loss once a week by weighing plants at predawn on two consecutive days, root zone temperature once a week, and stomatal conductance one time late in the production cycle. In 2004 the same experimental setup and data collection was followed, except with three new species, sticky geranium (Geranium viscossissimum), gooseberry globemallow (Spaeralcea gros-sularifolia), and Rocky Mountain penstemon (Penstemon strictus). The graduate student working on the second study is currently writing his thesis, but initial analysis of the data shows that pot-in-pot production created more favorable growing conditions. Temperatures of the plants in the PIP system were up to 10 C cooler than those grown above ground. We also observed that PIP-grown plants had lower total plant water use rates and higher stomatal conductances than those grown above ground. The integration of these responses in terms of growth showed that PIP-grown plants in the higher mountain species (Geranium viscossissimum and Aquilegia caerulea) were higher than those grown above ground. However, for the species found at lower, drier conditions, Mirabilis multi-flora and Spaeralcea grossularifolia), did not have more growth than those plants growing above ground. The two penstemon species (P. palmeri and P. strictus), were intermediate. The final report will be submitted when the graduate student working on this project has an acceptable draft completed.
2. A final, third study funded by separate state and federal sources will complete this overall project. The initial project objectives as funded by SARE were to investigate three plant sizes: small (1-gallon perennial wildflowers), medium (3- to 5-gallon shrubs) and large (10- to 15-gallon trees). The private nursery collaborator in Grand Junction did complete a study with 10-gallon pots and found that pot-in-pot production shortened their production times. We investigated medium (in this case 3-gallon shrubs) and small sizes in the initial study comparing growing medium and irrigation systems in Logan, Utah, but only 1-gallon perennials in the second study that was conducted in Logan. This final third study will be identical to the second study comparing PIP to above-ground production, except that three shrub species (all 2-3 m high shrubs Mahonia fremontii, Fraxinus anomala, and Amelanchier utahensis) will be used in 5-gallon containers. The study will be run for three years in Logan, the time we anticipate will be needed until the plants reach marketable size.

Impacts and Contributions/Outcomes

This project continues to have an impact on production of Intermountain native plants, as one of the larger native plant nurseries in Utah, Wildland Nursery in Joseph, continues to convert production over to pot-in-pot. The initial private collaborator, Chelsea Nursery in Grand Junction, Colorado, has expanded their area of 10-gallon pot-in-pot production. A third nursery in Boise, Idaho, heard about this project by conducting a web search, contacting this project for information, and is planning on installing a pot-in-pot nursery. Because most of the production of Intermoutnain native plants will occur in rural areas where land is cheaper, the rural economy of the Intermoun-tain West will directly benefit. The results of this study will complement the new program marketing Intermountain native plants, Utah’s Choice, that is being developed by the Intermountain Native Plant Growers Association (INPGA) with assistance from the Center for Water Efficient Landscaping and the Utah Botanical Center at Utah State University by presenting members of the INPGA alternative, and lower cost, means of producing native plants.