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 www.instagarden.com). 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

The First Fruit Sets

So my routine is pretty well set by now ... I take care of the morning house stuff, drop the kids off at school, then come home and water and tend to the tomatoes. I've been watering every day, and the daily tending is pretty low impact. I'm snipping off suckers, tying up vines, trimming back errant shoots, and feeding weekly with Espoma Tomato-Tone organic fertilizer. I suppose successful tomatoes are as much about discipline and routine as anything else.

And look! The first fruit has already begun to set, so there are tiny tomatoes all over my plants. Pretty nice, huh? (Incidentally, the tomato pictured at left is an Azoychka. This is a yellow early-season tomato. I expect to start harvesting these right around Christmas. The other varieties are not this far along.)

The fungal problem is under control. After I found the leaf spot (see below), I removed all the affected leaves, bagged them up and disposed of them, then I treated with an organic copper fungicide spray weekly for a few weeks. It worked, and the plants are thriving and mostly free from any blemishes. So far, I haven't had caterpillars, but I'm just waiting ... I know they're out there.

I have, however, experienced a rather significant degree of blossom drop so far this season. There are a few reasons tomatoes drop blossoms early in the season: lack of sun, too cold, too hot, improper watering, and sometimes, just because they feel like it. For the most part, I'm not that worried about it. Let's face it, the beginning of this season stunk in South Florida—it was just too hot for tomatoes, so I'm not surprised to be losing my early blossom sets. But the season is long, and now that the weather is cool, I'm gratified to see fruit emerging. I don't expect to be wanting for tomatoes later on.

However, if you're experiencing severe blossom drop, and it's really freaking you out, you can use a product called Tomato & Pepper Set, by Fertilome. This product is a plant hormone that stimulates the plant to set fruit, even in adverse conditions. I've used it successfully in the past, when it stopped rampant blossom drop and hastened my tomato sets.

Lastly, I've been kind of keeping a secret for the past few weeks. I keep meaning to write about it, but my blog time is precious. So I'll give you a hint: in addition to the tomatoes I've been writing about, I started another experimental group, this time using pretty standard Better Boy tomatoes. But the grow set-up is unique and strange and unlike anything I've done before. Next time, I promise.

Ack! Tomato Leaf Spot

I knew it was too much to hope for ...

This morning, while I was watering, I noticed discoloration on the lower leaves of one plant. When I looked closer, I saw that the discoloration had spread throughout all the lower leaves of the plant—and I officially had a problem on my hands.

I took the leaf to a friend who farms tomatoes professionally and he confirmed what I suspected: I've got fungus. There are many fungi that affect tomatoes, and I don't know exactly which one this is, but I treated anyway. I first removed all the affected leaves on the plant, bagged them and threw them away. Fungus and bacteria can be highly contagious, so you have to be careful when you're handling infected leaves.

Then I treated every plant with a copper fungicide, which treats for fungus and has some antibacterial action. My friend recommended I also used Maneb, which is a stronger fungicide, but I'm going to hold off for now on that. Copper fungicide is rated for organic growth, and I want to keep my grow organic if possible.

But why did this happen? I've been careful, right?

I have a few thoughts on that. First off, the affected tomato plant gets less sun than I would like. I'm growing along the side of my house, and the winter sun is dipping too low on the horizon, so my neighbor's house shades these tomatoes throughout part of the middle of the day. In all, they're lucky to get three hours of direct sun, and that's just not enough. Second, and most important, my neighbor's sprinklers overspray onto this plant, and he waters in the middle of the night. So these plants were getting wet in the night. Finally, it's still too hot and muggy—these are perfect conditions for fungus.

Fortunately, this problem was not too widespread yet. The container tomatoes get much more sun—five to six hours of direct sun—and they are situated a ways away from the sick plant. So I'm hoping I can control this until the weather cools off and the affected plant gets tall enough that it grows back into direct sun.

Besides the obvious—lots of sun, don't let them get wet from above—this was a good reminder of another thing to keep in mind: it's always good to pay close attention.