ames, iowa: iowa state university extension and outreach’s “Gardening While Insulated” series continues with a discussion of fertilizing seedlings.
once the seeds have been planted in the flats, it will soon be time to fertilize them, to ensure the highest quality crop for transplanting into your garden. The iowa state university integrated pest management team has created a youtube video to explain how to plant.
Reading: When should i fertilize my seedlings
Seedlings should be fertilized after they are three inches tall and can be fertilized weekly thereafter until transplant. All plants need Nitrogen (N), Phosphorus (P), and Potassium (K), which are commonly listed on fertilizer bags as whole numbers, such as 2-2-3. These numbers are actually percentages, representing 2% nitrogen, 2% phosphate (p2o5), and 3% potassium (k2o). Fertilizing with organic materials is a bit more complicated than fertilizing with conventional synthetic formulations that are derived from petroleum products, since their nutrient concentrations are exactly the percentages indicated on the label.
Organic fertilizers are formulated from natural, animal- or plant-based substances, whose nutrient concentration can vary, based on the particular raw materials. The release of nutrients from organic sources also is highly variable, so crops should be monitored to determine if any deficiencies develop.
jaden gimondo, a horticulture graduate student at iowa state, demonstrates the types of organic fertilizers that can be used for transplants and the best way to apply them.
The most generic fertilizer source is compost, which is best used by mixing it into potting mixes at a 1:1 ratio. Composting stabilizes the nutrient content of manure and other organic materials and releases nutrients slowly, minimizing thus the loss of nutrients and possible environmental contamination.
In the presence of oxygen, microorganisms break down organic matter present in manure and other raw materials. Some commonly used raw materials in compost include animal manure, crop residues, straw bedding, and processing or kitchen waste. the elemental composition of the final compost depends largely on the chemical composition of the raw material.
General guidelines suggest that 10-25% of the compost will not be available to plants during the first year of application. estimates of availability of p and k in the first year are higher, at 40% and 60%, respectively. Organic fertility amendments such as compost and manure have been shown to improve the physical, chemical, and biological properties of the soil, so adding them to the soil prior to transplanting is also recommended. use only well-composted manure, as raw manure is strictly prohibited in organic production, unless it is returned to the soil at least 120 days before harvesting any crop.
All products used in organic production must meet organic requirements, as set forth in the USDA National Organic Program rules. Compliance can be verified if products bear an OMRI: Organic Materials Review Institute label.
Other fertilizers used in greenhouse organic transplant production include commercial dry formulations, consisting of aerobic turkey bedding compost, feather meal, and sulfate of potash.
Commercial formulations require calculations based on the level of fertilization you want, ranging from low to high dosage. follow label directions based on your plant’s needs. a similar commercial organic fertilizer that contains oilseed extract and comes in a liquid formulation is a naturally occurring organic plant food.
Liquid formulation rates are often expressed as parts per million (ppm) with the recommended nitrogen rate of 150 ppm for vegetable transplants.
One of the easiest and cheapest liquid organic fertilizers for small-scale production is fish emulsion.
Composed of recycled waste from fish processing, the nitrogen content of this fertilizer typically ranges from 2-3% n. Although the product is disinfected, it is better to apply it outdoors to dissipate the fishy smell.
Once your seedlings have reached six inches tall and temperatures have risen to 65 degrees at night for tropical crops like tomatoes and peppers, you’re ready to plant them and grow.
Products and vendors mentioned in this release are for example purposes only. no endorsement of these products or providers is intended.
For more information, contact kathleen delate, professor and organic extension specialist at iowa state university, at 515-294-7069, or [email protected]
Original photo: fertilizing seedlings.