Tuesday, April 10, 2012

Seen one container, seen 'em all?

Not so!! When it comes to growing tomatoes, container size and the material it's made of are extremely important!  Tomatoes need plenty of room for their large root systems to grow and plenty of soil volume.  The foliage and fruit need heat and sun, but the roots, not so much.

Tomatoes will do well in containers that can hold a lot of soil. That means at least 15-gallon containers, which hold one 2 cubic foot bag of potting soil. The nutrients in the soil in pots leach out quickly so I like to use fresh soil each year. Alternatively, you can replenish the soil with amendments just like we do in the ground. That's  light layers of fertilizer, inoculent, soil conditioner, and compost right on top of the existing soil.

Let's take a look at some container options:

Terra Cotta - well, I'm not really going to dwell on this. Clay pots soak up the water that you put down for your plants. They're heavy and hard to move, if you need to.  I never plant tomatoes in them. Some are quite lovely, but save them for your annual color.

Composite/Faux Terra Cotta - pretty much the same issue with water. They're lightweight and some are very pretty.  I use them, but not for tomatoes.

Heavy weight plastic - I have about 30 black, 15-gallon containers that I  have grown tomatoes in for years.  There are three or four nice holes in the bottom so they drain well. I do like to put them up on pot feet. That way, when they drain, the water runs off rather than pooling around the pot. The problem with these pots, though, is they're black.

It gets really hot here in the summer and the pots sit on top of my reclaimed basketball court. Hence, the pots get really hot.  As I mentioned before, tomatoes and their foliage like the heat better than the roots do. Last year, to minimize heat absorbed by the pots, I wrapped each one in a burlap bag. I cut open the bag, wrapped it around and pushed one or two garden staples into the soil to keep the bag in place. The bags remained on the pots for the duration of the season. The light color repels heat and when it was extremely hot, I watered down the bags to help cool them and the containers underneath.  This worked well and I was very happy with the results. This was a successful, although not very pretty solution.

Pulp Pots - I bought one of these pots about three years ago, fully expecting it to last only one season.  I'm still using it!  It did a fine job. Water drains, it doesn't get too hot.  I'll say more about this pot a few paragraphs down.

Smart Pots - This is my first season growing in Smart Pots.  I received a huge box full of samples in various sizes from the distributor who wanted my input on how these compare to the plastic.  What a wonderful gift!  These pots are made of breathable, porous fabric.  They are black but this material is said not to absorb heat the way plastic does so I'm giving it a shot.

Here's a little story about growing in pots:

Last February, we had extremely unusual weather. While in most years February is our coldest month, this year we had several days of 80 degree weather. Perfect for growing tomatoes.  So, when I found a three pack of big, beautiful tomato plants on sale at Costco, I just had to buy them! I wanted to get a jump start on the season! Knowing full well that it was still too cold at night and not the right time to plant them in the ground, I decided to try an experiment.

So, I planted one tomato in the pulp pot, one in the black plastic and the last in one of the Smart Pots. I put fresh soil in each container, then the usual additives in each planting hole, and then the tomatoes. I was excited and optimistic that  my desire to have really earl tomatoes would overcome the weather!

Of course, you know what happened.  34 degrees that night...and the next!  I was afraid to go out and look.

 When I finally got up the nerve I went outside and here's what I found - the tomato in the pulp pot was almost completely  limp and black. The bottom leaves were curled but looked salvageable.The tomato in the Smart Pot had gone limp, but not as badly as the one in the pulp pot.  I thought I could cut off a few branches and that it would grow back. The tomato in the black plastic pot was limp at the very tip, but other than that, it appeared quite fine.

What did I learn from that little exercise?  Plastic pots definitely hold heat. Pulp pots do not. Smart Pots seem to be the happy medium. Lastly, don't plant tomatoes in February.

So, while I will definitely use the plastic pots this season, I'm very excited about the Smart Pots. I think they're going to do quite well.  I'll keep you posted.

Want to know more about growing vegetables in containers? Think about signing up for my class on Container Gardening on April 29. For further information and to sign up for this class  email Laura

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