What Kind of Fertilizer Do You Use for Boston Ferns?
- Ferns require minimal fertilization. Expert sources such as the University of Minnesota Extension caution that using too little fertilizer on ferns damages plants less than the overuse of fertilizer. Under-fertilization of Boston fern causes a slight loss of depth in the plant's dark-green color. Over-fertilization causes browning in fern fronds that starts at the tips and spreads all the way to the base. Regardless of the type of fertilizer used, always fertilize ferns in moderation. When in doubt, refrain.
- Sources recommend different types of fertilizer for growing ferns. Any common liquid houseplant fertilizer works well on Boston ferns grown indoors. Fish emulsion also proves effective as fertilizer on ferns grown inside or in containers. A team of University of Florida (UF) horticulturalists recommends a 3-1-2 or 2-1-2 ratio fertilizer for Boston ferns grown in outdoor environments. Such fertilizers come in dry or liquid types. UF horticulturalists report that most gardeners prefer the liquid variety, because it is easier to apply.
- University of Florida horticulturalists recommend very specific rates for fertilizer application on Boston ferns grown outdoors: 2.9 pounds of actual nitrogen per 1000 square foot of growing space, per month. Always check the amount of actual nitrogen in fertilizer and base the application on this formula for outdoor growing. When growing Boston ferns indoors, apply household plant fertilizers at half the rate recommended on the packaging of the fertilizer. University of Vermont professor Dr. Leonard Perry recommends applying fertilizer at this rate for indoor ferns once a month from April through September.
- Boston ferns express a complete intolerance of frost. Any frost quickly kills all specimens to ground level. However, the rhizomes of the plant remain in the soil and result in complete regrowth of ferns once cold weather passes. Never provide more than the recommended amount of fertilizer or an alternate type of fertilizer as a means of encouraging regrowth. Such an application may lead to problems with regrowth.
Planting Boston fern in moist soil, rich in organic matter, promotes healthy growth more than the use of fertilizer. Organic matter includes things such as compost, sawdust, mulch and manure. When planting Boston fern, mix this material with a moist, well-drained soil medium.