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Home  > Question of the Week

Question of the Week

Permalink How can I manage the temperature in my hoop house?

Answer: Hoop houses generally have no heating or cooling systems other than natural solar heating and natural ventilation. As a result, hoop houses provide less control of environmental conditions than full greenhouses. However, there are design techniques that can help control temperature—and also help extend the growing season—such as improving coverings, decreasing air leakage, and increasing insulation levels.

The structure of the hoop house helps determine the interior temperature. A width-to-length ratio of 1:2 will produce the highest passive solar gain. Narrow tunnels tend to lose more heat because of the ratio of the perimeter to the total growing area. Taller tunnels tend to have better ventilation and air movement.

It's also important to choose the right covering. Greenhouse-quality polyfilm is superior to construction plastics like visqueen, providing more wind- and uv-resistance, better light transmission, and longer life. Polyfilms do lose ability to transmit light over time, however, and may need to be replaced according to the manufacturer's warranty.

Some people use a double layer of polyfilm, which provides slightly warmer temperatures and also provides increased protection against snow and wind. The downside of a double layer is reduced light levels.

To gain additional heat from a double layer, you can use a blower between layers for extra insulation. And for even more protection, people sometimes use a low tunnel inside of a high tunnel, but it is important to closely monitor ventilation.

To reduce interior temperatures in summer months, use shade cloth or remove the plastic covering from the hoop house. Shade cloth lowers the temperature in the hoop house and can result in less watering and also reduce plant stress.

For more information, watch the ATTRA video Hoop Houses for Extending Your Growing Season, available at Topics include the uses and benefits of hoop houses, including increases in crop quality and yields; types of hoop houses; construction, materials and cost estimates; management of crops, soil fertility, pests, and weeds; and the economics and marketing of crops.

Additionally, the ATTRA publication Sustainable Season Extension: Considerations for Design will provide more information on greenhouse design elements and their effectiveness at extending the growing season in cold climates.This publication is available at

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Permalink Where can I source organic seeds in my area?

Answer: The ATTRA website offers several databases, including a directory of organic seed suppliers.

This database identifies organic seed sources for both agronomic and horticultural crops. Some national, mail-order suppliers of untreated seed are included, with emphasis on small, alternative seed companies offering open-pollinated vegetable, flower, and herb seed.

Just go to the ATTRA website at, click on Databases at the top of the page, and scroll down to find the Directory of Organic Seed Suppliers link. The directory offers a map of the U.S. and Canada and provides a list of suppliers once you've clicked on your state.

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Permalink How can I use living fences?

Answer: Living fences are fences made of live trees and shrubs. Their installation and use is common in many parts of the world, including Europe, Asia, and Australia. While historically used in the United States as livestock fencing, living hedges are being increasingly implemented for the many additional benefits they offer to sustainable agricultural systems. Living hedges are an important component to permaculture design as their multiple functions are integrated in the planting of forest gardens.
The benefits of a living fence include: 

-Crops are protected against harmful pests.

-Habitat for beneficial predator animals and insect pollinators.

-The living fence can act as a windbreak.

-It can prevent soil erosion.

-Various products, such as food, firewood, medicines, timber, and nectar, can be harvested.

-It can prevent terraces from collapsing.

-It can be used where materials for fencing are difficult to obtain.

-The living fence can save money.

For more information, see the ATTRA publication Farmscaping to Enhance Biological Control, at This publication contains information about increasing and managing biodiversity on a farm to favor beneficial organisms, with emphasis on beneficial insects. The types of information farmscapers need to consider is outlined and emphasized. Appendices offer information about various types and examples of successful 'farmscaping' (manipulations of the agricultural ecosystem), plants that attract beneficials, pests and their predators, seed blends to attract beneficial insects, examples of farmscaping, hedgerow establishment and maintenance budgets, and a sample flowering period table.

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Permalink When should I supplement my pasture-grazed livestock?

The nutritional concern for ruminants centers around energy (i.e., carbohydrates), protein, minerals, vitamins, and water. Energy (carbohydrates) is responsible for maintenance and growth functions of the animal, and for the generation of heat. Protein grows tissue and performs other vital functions. Other nutrients and minerals such as vitamins A and E, calcium, phosphorus, and selenium can be fed "free choice" as a mineral supplement.

Cattle, sheep, and goats--by nature, grazing and browsing animals--grow and reproduce well on pasture alone. However, an intensive and industrial agricultural production philosophy has dictated that crops and animals should be raised faster, larger, and more consistently than a pasture system can deliver. Thus, confinement systems with delivered forages and concentrated feeds have been the norm since the 1950s. Raising animals on grass is slower than raising animals on grain. However, a pasture-based livestock producer will, with careful planning, realize cost savings and subsequent profitability through the efficiency of relying on the natural systems of nutrient cycling, biological pest controls, and perennial pasture productivity.

The major operational expense confronting the livestock industry in most parts of the United States is for supplemental feed. In temperate regions of the country that experience adequate rainfall and a lengthy grazing season, supplementation on green, growing, vegetative, well-managed pastures should not be necessary. However, young and lactating stock require more energy and protein than mature, non-lactating animals.

Supplementing energy is helpful on vegetative, well-managed pastures for more efficient utilization of forage protein (for high-producing animals). Supplementing with protein is necessary on low-quality pasture and rangeland or when continuously grazing temperate warm-season pastures.

For more information, see the ATTRA publication Ruminant Nutrition for Graziers at This publication provides managers with tools and references to consider biological and climatological variables and make decisions that ensure the ecological and economic viability of a grass-based ruminant livestock operation.

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