The one advantage of growing tomato plants in a container garden is that you can start the seeds in January no matter where you live. In fact, even if you are in Zone 10, you should start thinking about starting your seeds now. Why? It can take at least 85 days from seed to harvest, and tomatoes are a warm weather crop. So, it’s time to start thinking about which type of tomatoes you want and which containers or planters will work best to start them.
Growing Tomato Plants from Seeds
We are growing beefsteak tomatoes. Now, living in Zone 10 means that we have some extra time – we can harvest throughout the fall and into winter without much of a problem in Los Angeles. But if you live in a region that sees very chilly temperatures come September, you’ll need to make the most of your shorter growing season.
Typically, gardening experts recommend starting your seeds at least six to eight weeks before the last frost usually occurs. That way, the seedlings will be sturdy enough to start hardening off before transplanting them into the ground or outdoor container garden.
Planting Tomato Seeds in an Indoor Container Garden
If you’ve seen our earlier attempts at growing tomatoes in pots inside before, you’ll know that we started with seedlings that quickly grew in 2020. We were so pleased with how those went that we began with seeds for our next crop.
This time, we chose an organic potting mix, as well as compost and an earthworm castings blend to start the seeds. We used supplemental full-spectrum lights to help give the tomato seeds and seedlings the eight hours of direct light they need to grow.
We also chose to plant the tomato seeds indoors in self-watering containers to help prevent root rot and to allow the plants themselves to control how much moisture they needed. Plus, I have a terrible tendency to overwater, so this stopped me from going too heavy with the water. Once those grew into seedlings about eight inches tall, we started hardening them off.
Moving Your Tomato Plants Into Outdoor Containers
We transplanted our hardened off tomato plants into our outdoor container garden that Andy built as soon as temperatures were in the 60s. Light frost can harm the plants, so keep them inside at night if your early spring temps dip significantly.
We love the raised garden bed that Andy built because it has a trellis. Our beefsteak tomatoes grew taller than I am, and they needed that support. Because of the size, we only transplanted two seedlings into the 4-foot container boxes. This gave the roots the freedom to go down (you need to plan for at least 18-20 inches of downward root growth) and sideways. The systems need to be strong and the branches supported because once the fruit starts coming in, it will be heavy and weigh down the branches.
Pruning Tomatoes in Planters
I’m terrible at pruning. You are supposed to do weekly prunes of suckers so that the fruiting branches can be the focus of the plants’ nutrition. But there is something about pruning beautiful leafy suckers that I avoid. One of my goals in this planting season is to be better at that. We’ll see.
Fertilizer for Your Container Garden Tomatoes
We started with a nitrogen-rich potting mix and compost. But as the tomato plants grew, we regularly supplemented the potting mix with either organic vegetable fertilizer or Neptune’s Harvest Tomato & Veg (2-4-2) liquid fertilizer. A small amount every two weeks goes a long way to keeping your tomato plants thriving throughout the growing season.
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