Soilless Media Plant and Soil Science Standard 4 Objective 2

Soilless Media  When raising plants there are many different options for a growing media  Most of the time think all plants grow in soil  This is not the case  Does anyone know the kind of growing media we commonly use in our greenhouse?  Is is soil? or a Soilless media?

Composition of Potting Mixes  Soil (loamy, good structure, pesticide-free)  Coarse aggregates for drainage (sand, perlite, vermiculite, shredded plastics)  Organic amendments to hold water (sphagnum peat moss, tree bark, sawdust, rice hulls, shredded coconut hulls, wood chip/sludge compost)  Most contain no soil

Advantages of Soilless Mixes  sterile  lightweight  good moisture retention and drainage  free of weed seeds

Disadvantages of Soilless Mixes  minor elements are missing  light weight - pots tip in strong wind  transplants may not adjust well to new media

Content of mixes  Soilless mixes contain various combinations of the following materials.

Perlite  improves aeration  of volcanic origin

Spahgnum Moss  Dehydrated remains of acid bog plants  Used to cover seeds because it is lightweight, controls disease, and holds moisture.

Peat Moss  Partially decomposed underwater vegetation.  Holds moisture well  Low in nutrients

Vermiculite  Exploded Mica  Improves aeration  Holds moisture very well

Limestone  Raises pH

Hydroponics  Technique of growing plants in non-soil medium using feeding mixture of essential plant nutrients dissolved in H 2 O  Three main types  static solution culture  medium culture  aeroponics