4 Tips For Using CRF In the Greenhouse
Follow these tips to effectively implement controlled-release fertilizers in the greenhouse.
December 21, 2011
Using CRF in the greenhouse isn’t quite as straightforward as using it in a nursery setting. However, by following these tips, growers can effectively implement CRF in the greenhouse:
1. Remember, root zone temperature drives CRF nutrient release. Thus, CRF will release nutrients more quickly as temperatures rise. It’s important to consider this carefully when selecting products and rates. Everris recommends homogenous, complete, 100-percent-coated products (e.g. Osmocote Plus) for greenhouse production.
2. Don’t trust bag label rates for greenhouse crops. These rates are generally intended for container nursery use, and rates for greenhouse crops should be much lower.
3. If you incorporate CRF into growing media, you need to use the mix up in two to four weeks. The CRF will begin to release nutrients as soon as it is blended into the soil mix. Quick use of the media will ensure that soluble salts don’t build up in the mix and that the crop has full access to nutrients from the CRF.
4. It is more difficult to monitor growing media with CRF mixed into it. If you’ve selected the proper rates, EC in the root zone will actually be lower than the EC to which you’ve become accustomed if you’ve only used WSF in the past. Visual assessment of crops and tissue analysis are more useful testing tools, especially when the fertilizer program consists entirely of CRF.
Fred Hulme, Ph.D. is Director of Technical Services at Everris.