Production tips: Growing media

If your growing media mix has you perplexed, it may be time for a change. Or at least a chat with some experts. We asked Steve Jarahian, director of technical services at Oldcastle Lawn & Garden and John Keller, vice president of operations at Monrovia, about custom-blended growing media.

Q: When should a grower consider using custom-blended growing media?
Steve Jarahian: It’s necessary to consider custom blends if the crop has a specific growing requirement, such as a lower pH to protect against fungal diseases. Also over time, most growers tweak their mixes to work under their specific conditions. If this is the case, a grower may want to consider a custom blend and working with a soil producer to get the right “recipe.”

John Keller: If they’re making a change in production practices — like changing liquid feed or length of production time — it may signal a need for a soil mix change. Often when growers are fine-tuning their systems to be more efficient or to grow specialized crops, there may be a need for a custom blend.

Q: What questions should growers ask during the process of getting custom blends?
Steve Jarahian: Ask the supplier — Can I get a sample to trial before I commit to a truckload?

• Can I buy less than a truckload?
• What is the lead time for a custom blend?
• Do you test your custom blends the same way you test your standard growing mixes?
• Do you have a custom bag?
• Do you label the pallets so my workers will not confuse the mixes?

John Keller: Ask yourself — Does it give me the benefits I need? What are the tradeoffs in cost? Do I have the increased level of management needed to keep track of a custom blend? And the biggest question is, what blend do I need? Not just the physical components like bark or peat, but the micronutrient needs as well.

Q: How often should custom blends be tested?
Steve Jarahian: Too many times, soil is only tested when a problem arises in a crop. If you are able, retain a sample of the mix and send it to an independent lab before using the mix. A good, reputable soil producer will have tested the mix several times before you receive it and should have a retained sample as well if questions or problems arise.

John Keller: Whether it’s a custom or generic blend, you should test it before you use it and do careful monitoring throughout production.

Q: What’s the proper way to store growing media?
Steve Jarahian: Store mixes in a cool, dry area whenever possible. Only order what you can use in a six-month period. As mix ages, it will become harder to wet. If you have a custom blend with control-release fertilizer, the soluble salts can harm plants because it can release in the bag if stored too long. This material is best used in 30 days or less.