Hi Sammy,

Tomato plants have both kinds of roots--the deeper tap roots and the mass of fibrous roots closer to the soil surface. As far as I know, all the roots feed the plants.

The kind of roots any tomato plant will have depends on how it is grown. Tomatoes that are direct-sown into the field have a larger, deeper tap root. In some cases, direct-sown tomato plants can have a 6' taproot. Those that are started in flats, pricked out and potted up into individual containers have a weaker tap root but a more well-developed fibrous root system. I believe the more times they're potted up into successively larger containers, the better their fibrous root systems. Once they are transplanted into the ground, most of their fibrous roots will be found within the top ten inches of soil although some lateral roots can run quite a length from the plant....I've had some go out 2' to 4' in drought years when they're more aggressively searching for water. However, some studies show that those plants potted up several times do not outperform those potted up only once or direct-seeded. I do think they produce earlier though, based on my own experiences growing tomatoes that are potted up a couple of times as seedlings. For folks like us in hot climates where heat shuts down pollination and fertilization fairly early in the summer, it is better to have plants with fibrous roots that will produce fruit early before pollination and fertilization are impeded. That's why you don't see us direct-seeding in the ground here in March or April....because we wouldn't harvest anything much until fall.

You encourage your tomato plants to grow more fibrous roots by planting the plant deeply in the soil, whether it is in the ground or in a container. The adventitious roots form from those little root hairs on the main stalk. I always plant my tomato plants as deeply as I can to encourage those adventitious roots.

All the tomato roots feed the plants. Ideally, you feed the soil by adding compost, manure, etc. to the soil and letting the plant roots take what they need from the soil. That's easier to do with in-ground plants that can stretch their roots as far as needed (within reason) to find the nutrients they need.

With plants in containers, I add compost, composted cow manure, a handful of blood meal, a handful of bone meal, a handful of Tomato Tone plant food, and maybe greensand or soft rock phosphate to the containers every year to make up for whatever leached out of the container or was used up by the plants during the previous growing season. It isn't an exact science. I just try to remember what I observed the previous year in terms of plant performance, and add what I think the soil needs.

If the nutrients are in the pots, the roots will find them...high, low or whatever. When I add the nutrients every year, I stir them into the soil-less container mix already in the pot so it is all well-mixed.

Because container-grown tomatoes are watered often, nutrients leach out of the soil, you may find you need to feed your plants as often as weekly with a water-soluable fertilizer. I find that to be necessary in June, July and August when I'm watering daily as the daily watering leaches out nutrients.

I've linked some info on various studies of tomato roots. In the first photo, you'll see the difference in a tap root on a young direct-seeded plant versus the more fibrous root system on a transplanted seedling.

Dawn

Here is a link that might be useful: Studies of Tomato Root Growth

Dawn, you have come through once again. This is a desperate weekend with tomatoes and roses, but I need to get these ammendments before I put the tomatoes in the pots. Right now they are just sitting there in their little containers.

Thank you so much.
Sammy

Sammy

You're welcome. If you don't want to hunt down all those organic amendments, you could just add some fresh potting soil like Stagreen or Miracle Grow that has a pelleted slow-release fertilizer. They both work just fine, unless you're wanting to grow organically with no synthetic fertilizer.

Dawn

I will add some of my observations from my experimenting with direct seeding versus transplanting. And also transplanting at a young age before the tap root gets turned. Two years ago in the severe drought. I had 6 direct seeded plants and 82 transplanted. Five of the direct seeded plants were in my top six that year production wise. Plants from the same seed packet that were transplanted didn't do as well. When I pulled the plants after they a freeze killed them there was a big difference in the size and length of the tap root between them. I'm not sure how deep they went on a direct seeded one. I had one tap root 3' long and still bigger than a pencil where it broke off. I had first thought it was because the roots got down into cooler soil. I will add I could go 1-2 days longer between watering on the direct sown plants. My thoughts have changed some as to the reason for this. If you've read my post about my soil issue I now feel the tap root was getting down into soil that had more desirable levels. Last year there wasn't as much difference. But to be fair I didn't get them started as early. This year I didn't start any as I had planned due to the weather and other projects. I do have plants coming up in the cold frame now. And if the weather cooperates may transplant some at a few days of age like a man who I respect in WI does some. In the future I plan on doing more experimenting. The advantage to transplanting those started inside is you can transplant bigger plants. Which is important for those that need to get tomatoes before the heat sets in. The way our cold has lingered the last few years then the heat sets in early that hasn't worked as well here either. I still start the majority of mine inside. Now with the cold frames and greenhouse will be starting more in them and also direct seeding more if I have the time. It is interesting when you pull the plants to see the difference in the root system. In my case more dramatic than the pictures. When I was young and we lived in an area where you had early and late tomatoes the late tomaotes were always direct sown outside in July and they did well. Jay