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Episode 75: The Science of Soil with Dr Mark from Metrolina Greenhouse



So excited about this highly request episode on the science of soil. Finding a “soil expert” was kind of tough, but when I met Dr Mark Yelanich on a recent visit to Metrolina Greenhouse, I knew I had found the answers to my prayers. Dr. Mark has been the Director of Research at Metrolina Greenhouses for the past 14 years. Metrolina Greenhouse is the single-site heated greenhouse in the United States at 162 acres under roof. The Metrolina Research department focuses on working with plant breeding companies to find varieties that will delight home gardeners and help them be more successful. The research department also works on finding improved ways of producing our plants to make Metrolina more sustainable and efficient. Before Metrolina Dr. Mark worked for Scotts Miracle Gro (SMG) where he was the Senior Scientist in charge of research on Miracle Gro branded potting and garden soil (and received three patents on soil products). Dr.Mark received his Ph.D., Masters and bachelors from Michigan State University (The Harvard of Horticulture). He is married to Lisa for 26 years and has two daughters Hannah and Emily (sadly neither are going into Horticulture but he is still very proud!)

Today he joins me to break down the different components of soil, and why choosing the right soil is so important for the success of our houseplants!

If you are interested in seeing Dr Mark and Metrolina Greenhouse, check out the behind the scenes tour Dr Mark gave me when I was in North Carolina! You see the entire process of what it takes to grow a plant in a commercial greenhouse!

In this episode we learn:

  • How Dr Mark became a soil expert
  • Difference between outdoor and indoor soil
  • Why to NEVER use outdoor soil
  • What mixes to use for indoor plants
  • What makes up potting mix: peat moss, perlite, pumice, bark, vermiculite, coco coir, earthworm casings, various “meals”, fertilizer pellets
  • Fertilizing practices (brief overview)
  • Best ratio for indoor potting mixes and what to include (and what not to include)
  • Best way to store soil
  • Is reusing soil ok? What’s up with “baking”soil?
  • How and when to repot your plants
  • When to start fertilizing
  • Pest control
  • Is the white mold on the top of the soil going to kill a plant

Mentioned in today's episode!

Check out my tour of Metrolina Greenhouse with Dr Mark!

If you are wondering what soil and fertilizers I use on my plants, here are the links to the Espoma Organic products I use.


Thank you to today's episode sponsors!

Soltech Solutions makes luxury grow lights that look like high end modern light fixtures with cutting edge grow spectrum for houseplants and dwarf fruiting trees. I have three of their Aspect pendant lights in my apartment and love the launch of the new Highland Track Light System! For 15% off a light of your own, visit and use code Bloom15 at checkout.

Osea Malibu is the original plant-based, non toxic skincare derived from seaweed plant friends- it doesn’t get more planty than that!!! Each product is infused with sustainably-sourced, organic Patagonian seaweed and 
active botanicals that leave your skin feeling amazing. I LOVE their Ocean Cleanser, Atmosphere Cream and Argan Oil! Visit  and use code “bloomandgrow” for $10 off your purchase of $50 or more!


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