Times are tough for the media and soil industries. As with many products, international shipping issues are causing problems obtaining many media components; vermiculite is no different. Though the US does have some domestic vermiculite mines, many products are imported. The horticulture industry must rely more heavily on domestic sources, which can only ramp up production so much. This article will discuss what vermiculite is, what it does, and how growers may be able to meet those purposes with product substitutions and protocol changes.
Vermiculite is a mined product, gathered from special mines across the globe. In its raw form, vermiculite flakes look similar to bits of mica – they are thin, shiny, and lightweight. Once collected, vermiculite flakes are then graded by size and exposed to high heat inside of special furnaces. The flakes rapidly expand as trapped water vaporizes, resulting in the fluffy, flakey product incorporated into many potting soils and gardening products.
Once incorporated into media, vermiculite helps accomplish several goals:
1) helps maintain soil aeration and prevent compaction.
2) holds onto nutrients.
3) helps to control moisture and prevent dry backs.
With these qualities, we find that vermiculite usage is most popular at the seedling and germination stage, helping to provide well aerated, moist environments with readily available nutrients. Many growers make blends of peat and vermiculite for a wet but aerated germination media, use a healthy layer on top of germination media to cover seeds, or direct seed into vermiculite. Without vermiculite, growers can still achieve these conditions with some careful planning.
Irrigation scheduling: Consider changing your watering frequency when moving away from vermiculite. Soils may dry down faster without this component; shorter irrigation intervals can help mitigate this issue.
Environmental Controls: Monitor your air temperature, air movement, and humidity conditions in your production space. These factors greatly impact how quickly media dry out.
Explore other medias: Be flexible with your production process as supply chain issues come and go.
Perlite is good for aeration but not for moisture retention. Perlite can be used for all size plants and pots and comes in a variety of grades (sizes).
Wetting agents, such as AquaGro 2000G or AgAide, added to irrigation water or media will help to maintain uniformity of wetness and help growers get the most out of each irrigation.
Peat-based medias are great choices for thirsty plants. This base has good general water retention but needs some help with aeration. Combining peat moss and perlite can achieve many of the same goals as vermiculite. Peat mixes with finer particle sizes are great for germination mixes, while coarse particles are better for larger plants.
Coir-based medias are increasingly popular and promote faster drainage. Mixes of peat, coir, and perlite provide a good range of drainage, moisture retention, and aeration conditions for growers to choose from.
Inert and stabilized medias like Grodan rockwool, Oasis foam, and Jiffy Preforma are great choices for growers starting from cuttings rather than seeds and provide optimal water holding and aeration conditions while providing structure for unrooted cuttings.
Lastly, changes in production protocols can lead to unexpected changes in disease pressure. Changes in media and environment often lead to changes in humidity and moisture content, which can lead to fungal or bacterial problems. Be ready to deal with these preventatively by incorporating or applying preventative treatments such as biofungicides and brushing up on your general sanitation protocols.
Wetting Agents
74-1249 120lb AquaGro 2000g
74-1379 1 Gal Brandt Ag Aide
Soft Chemistry
71-13301 1 Gal BioWorks Cease
71-3040 1 Gal OHP Triathlon BA
71-1372 5 Lb Growth Prod Companion
Media
Media selection will be influenced by availability – contact your Griffin rep for more info!