Monday, November 30, 2009

Growing in Coconut Grow Bags

One of the cool things about this blog has been hearing from readers, sometimes with questions and sometimes with tips and photos of their own gardens.

Among these readers was a gentleman calling himself Boca Bob, and he sent me pictures of his South Florida vegetable garden that kind of blew my mind (he runs a website at He was getting amazing results with a system I was wholly unfamiliar with. Well, I'm nothing if not curious, so I did a bunch of research and set up another tomato grow elsewhere in my yard. Here's the story behind it ...

This set-up is essentially the same system used by professional tomato growers in greenhouses (so-called hothouse tomatoes). The growing medium is coconut coir, which comes in expandable 5-gallon bags from a company called Hydro-Gardens. See those black bags? Basically, you buy the bag, which comes with the coir brick included. You add water and presto! It expands into a 5-gallon pot.

Coconut coir is a bit different than peat or other growing media. It doesn't need to be adjusted for pH, but it's just about completely sterile. There are NO nutrients in coconut coir at all, so you have to add everything. In this case, I decided to abandon organic tomato growing completely and go synthetic. I'm curious if it will affect taste ...

Additionally, I didn't start these tomatoes from seed, but used Better Boy starts I got from my favorite garden center. Better Boy is a rough-and-tumble backyard tomato. It's a heavy bearing red tomato, resistant to all sorts of problems, and tasty. I've grown them before, so I'm familiar with how they should act.

At planting time, I amended the coir with gypsum, and I also threw in a bit of bone meal just to make sure. This will hopefully handle the calcium requirement. For magnesium, I'm using a 1/4 teaspoon of Epsom salts with every third or fourth watering. For nutrients, I'm using the Miracle-Gro general tomato fertilizer at 1/2 strength and feeding every two or three days (I'm watering every day). To train the vines, I drove large landscape stakes into the ground and I'm tying the vines to rope strung between the stakes. Couldn't be simpler.

Oh yes, I'm also experimenting with a weekly foliar micronutrient spray on one of the bags. I'll cover this in greater depth later, but in brief, a foliar spray is fertilizer or product that is applied directly onto the leaves. To use a foliar spray, you mix up the solution and use a garden sprayer to soak the plant down. You have to do this in the morning to avoid fungal problems. I'm using a product called Key-Plex, which is formulated with defensive proteins and micronutrients. According to the company, Key-Plex helps increase the plant's immunity to blight and other diseases while increasing yields. My test is obviously unscientific, but I'll post photos and results as they become apparent.

So far, this grow has gone surprisingly well. It took me a little time to get used to the coir. It doesn't compact like peat, so when you water it, the coir has a tendency to wash away from the plant's stem. You have to be more careful with watering (professionals use drip irrigation system). But the plants have bloomed heavily and are already covered with immature fruit. One of the plants is suffering from rolled leaves, but its fruit is unaffected. Otherwise, they're healthy, happy maters.

Up next: Topping Your Tomatoes


  1. thank you for sharing with us. you have a great blog! This is a good way to grow not only tomatoes, but more tumors.

  2. Very useful post Thanks to sharing wonderful articles
    coir grow bags