1. How does it work?

Edenferns are natural hyperaccumulators of arsenic, concentrating arsenic from soil and water in its fronds at levels 200 times greater than in other plants. The fronds are then harvested for disposal. The process is much quieter, and in most cases much cheaper, than alternative treatments such as excavation. Topsoil is preserved as the arsenic is removed.

2. How much shade and water does the Edenfern need?

Edenferns grow best in partial shade, but can tolerate full sun if it is exposed to full sun gradually. We recommend using shade cloth or similar fabric to protect the ferns when first planted. The ferns appreciate frequent watering but should not be allowed to become waterlogged.

3. Do I need to add soil amendments for good plant growth?

The ferns grow best in soils that are near neutral to moderately alkaline pH. Adding limestone to neutralize excess acidity to a pH between 6.5 and 7.5 is beneficial. Because Edenferns have the same nutrient requirements as other plants, you may need to apply fertilizer such as 15-15-15 monthly.

4. How long does the fern take to reduce soil arsenic by 10 mg/kg (ppm)?

The time required to reduce soil arsenic by 10 mg/kg depends on the soil arsenic level and on growing conditions. Assuming the soil has 50 mg/kg total arsenic, it typically takes about 4 months for Edenferns to reduce soil arsenic by 10 mg/kg.

5. Over what range of soil arsenic concentrations can the Edenfern perform?

The Edenfern can extract arsenic from a soil with arsenic concentrations as low as 1 mg/kg (ppm) or as high as 2,500 mg/kg.

6. Does the fern clean water as well as soil?

Yes, Edenferns remove arsenic from water very effectively. For mildly contaminated water, it can reduce arsenic to drinking water limits within two days.

7. Is the Edenfern perennial in my area?

Many sites can be treated effectively in a single growing season. The primary Edenfern variety is perennial in Plant Hardiness Zones 8-11 and is grown as an annual farther north and where winters are colder.

8. How big does the Edenfern grow?

The Edenfern is an attractive plant that can reach 60 to 100 cm (24 to 40 inches) in height and width. New fronds grow quickly after old fronds are harvested.

9. How deep is the treatment zone?

Typically the Edenfern is most effective at removing arsenic from the top 30 cm (12 inches) of soil. It can treat deeper areas if the soil is well tilled for better root penetration.

10. Are the ferns hazardous to people or animals?

Observing or touching the ferns is not hazardous to people or animals. Because arsenic is a poison (it was used for many years as a pesticide), ferns that have accumulated arsenic should not be eaten. In fact, one theory is that the ferns developed their arsenic accumulation capabilities to deter insect pests.

11. What do I do with the harvested fronds?

Harvested fronds should be dried and stored in a separate container for landfill.

12. Does the arsenic stay in the fern, or does it evaporate into the air?

Edenferns extract arsenic from soil, waste, or water, and store the arsenic in its fronds, where it is not volatile.

13. How do I know it will work?

The Edenfern has proven its effectiveness in a wide variety of soils and locations. To confirm its effectiveness at unusual sites, particularly larger sites, Edenspace offers a standard treatability study conducted in its laboratory with site soil. Some customers may also wish to conduct a pilot-scale field project, for which the cost depends on the site.

14. How many plants to I need?

For residential application, we recommend one Edenfern per square foot. In areas with a longer growing season,lower plant densities can be used. For larger areas there are other options that we can discuss with you.

15. Can other ferns native to my area also take up arsenic?

So far, only varieties of Edenfern (US Patent #6280500) have been determined to accumulate high levels of arsenic. Edenspace holds an exclusive license to the fern from the University of Florida Research Foundation.