At this month's meeting of the Golden Spades, Homestead's own guru Gene Sumi talked fertilizer - the basics, plus answers to everyone's questions about them.
Organics Feed the Soil
Organic gardeners know that the best way to get nutrients to their plants is to give them good soil, soil that holds onto nutrients (unlike pure sand) and has the microorganisms that can turn organic matter into nutrients (unlike the hardpan often left by developers after they've removed the topsoil).
So organic fertilizers, made from living things, release nutrients into the soil by way of microbial action. Compost works this way, improving the soil's structure while feeding our plants. And good soil structure means the soil can both hold and drain water, rather than waterlogging our plants in clay that doesn't drain, or starving plants in sandy soil that doesn't hold water long enough. Leafgro is a great compost product that's made from locally collected leaves.
Compost teas have recently become popular among savvy gardeners because they're such a great source of beneficial microorganisms. Another product that's very effective in doing this is Bio-Tone Starter from Espoma. It contains mycorrhizal fungi that stimulate roots to grow. It's so effective, Gene recommends that we use it when planting everything (except annuals). Even houseplants benefit from having this powder sprinkled around their roots. And that's the key - getting Bio-Tone to the root zone - so use it when you're planting or moving plants, rather than applying it on top of the soil. Why do our soils need this natural product? Because so often they're depleted by agriculture, or because developers removed the good soil and left the hapless homeowners with "builder's soil", which is a cruel name for rubble and clay. Even if your soil is adequate, plants benefit from an extra dosage of these root-starting fungi, and there's no worry about overdosing with them.
Interestingly, the only plant groups that don't benefit from the mycorrhizal fungi in Bio-Tone are weeds and plants in the brassica family - cabbage, cauliflower, et cetera.
Several audience members gave rave reviews for the fish-based Neptune fertilizers. One suggested that if you don't like the fishy after-smell, just wash your hands with some lemon juice. Gene told us about the ability of fish-based fertilizers, unique among all organic products, to be used quickly by plants. Fish- and seaweed-based fertilizers are the only organic products that are mixed in water and fast-acting. So, like synthetic fertilizers, they CAN be overused; read and follow the instructions.
Fertilizers like Miracle-Gro that are dissolved in water are fast-acting and therefore, can do damage if applied incorrectly. And the biggest mistake in their use is overuse, with users frequently doubling the dose in the mistaken assumption that more is better. But no, more is worse! So follow instructions on the package carefully.
The use of these fast-acting, chemical fertilizers makes soil irrelevant except as a way to hold up the plants, because the plants are fed directly, like intravenous feedings that short-circuit our own digestive systems.
The University of Maryland now recommends feeding lawns just once a year, in the early fall. Applications of high-nitrogen fertilizers in the spring just produce excessive growth (touted as "greening-up") that just creates the need to mow more frequently AND stresses the plants when the summer heat and drought come.
But what if you didn't feed your lawn last fall - okay to feed it now? Gene's answer is yes, with the organic fertilizer Milorganite. It won't cause excessive growth. With it and other organic fertilizers "You just can't screw it up."
Are there any lawn-care companies that use organic fertilizers? Golden Spaders suggested Natural Lawn, a national chain that not only uses organic fertilizers but tests the soil before applying anything to make sure it's really needed.
Recently a new law concerning fertilizer use went into effect in Maryland that reduces the amount of phosphorus in lawn fertilizers - because excess phosphorus has been running off into the Bay and creating dead zones. Not to worry - almost all Maryland soils have plenty of phosphorus, so this restriction won't be the downfall of our lawns. The other mandated change we're seeing in lawn fertilizers is the reduction in nitrogen they contain, again because any excess in nitrogen runs off into our waterways. This is only a problem in synthetic fertilizers, since organic fertilizers already have lower amounts of nitrogen, and aren't fast-acting and likely to wash away.
Does your lawn have excessive thatch? Try spraying it with compost tea. It's proving to be quite effective in breaking down thatch.
So what about potting soils that come with fertilizers in them? Not to worry - because of the much lower risk of overfertilizing annuals, the plants most often grown in containers. Annuals "live fast and die young" and thrive with regular feeding. It takes a lot of energy to keep blooming for 4-5 months, as they do.
Don't fertilize deciduous (leaf-dropping) plants when they're dormant, without leaves. It would be a waste of money because without leaves, the plants can't use the nutrients - it's leaves that create the "turbopull" that brings water and the nutrients it contains up into the plant. When the leaves first start popping out in the spring IS a great time to feed, however.
Is it okay to use fertilizers that have been sitting around for years? Yes, they have a very long shelf life - the synthetic ones, that is. The organic ones CAN get too old and should be kept under controlled temperatures. Fish products, for example, can ferment over time and under the wrong conditions.
Separate Fertilizers for Every Plant Group?
What's up with all the specialty fertilizers on the market these days? Do we really need to use a different fertilizer for tomatoes, for annuals, for trees, and so on? Gene says these new labels are mainly about marketing, rather than actual need. Garden-Tone is a great all-purpose fertilizer that can be used on anything, and if your pH needs adjusting, go ahead and use Holly-Tone for acid-loving plants. Use whatever you have and don't worry about what plant group it's labeled for.