Where do weed seeds come from?
There are a number of potential sources of weed seeds. Very commonly, ventilator fans often blow weed seeds into the greenhouse from the outside. Other potential sources include: • Contaminated crop seed • Infested plugs and rooted liners • Infested plants shipped to the greenhouse from outside sources • Ponds and irrigation systems • Uncovered soil under benches, in walkways, etc. • Poorly stored growing media, pots, plastic • Adjacent fields, drainage ditches, etc. Growing media can also harbor weed seeds. When considering growing media, look at raw material sources as well as processing and handling procedures. If you blend your own growing media, strive to avoid adding weed seeds via the use of mineral field soil or other components that are poorly composted. Commercial growing media companies work hard to exclude weed seeds in their quality-assurance programs by actively managing weeds in their raw material sources, production areas and during shipping. Additionally, they aim to h
