<Do I need to go ahead and cut growth tips?>

Why do you think you need to do that? Pruning is never "required" it is merely an option some use because they have very limited space or are using a less-than-ideal support structure for the plant. But you lose all that future production from the plant. 6' is nothing for many indeterminate varieties.

FAQ: What-is-the-difference-between-determinate-and-indeterminate-tomatoes

My first season gardening so I don't know what's necessary. Do I need to limit each plant to 6 trusses? I'm just not sure how to contain a +10' plant.

That's why I asked why you thought you might need to. Some new to it mistakenly think it is required for the health of the plant.

There is no need to restrict number of trusses on any tomato plant and attempts to do so only cost you lost production. As long as it is provided with sufficient water and nutrients it will just keep on producing (since these are indeterminates) until killed by frost or disease.

But the method you use for support, if insufficient, may force you to do some pruning. Stakes are very limiting, those 3 ring things are generally regarded as a waste of money, but using Florida weave, cattle panels, trellis, or top quality tomato cages easily cope with 10' plants. 6' high and as the plant tops that it just drapes down the outside and keeps on growing.

Tons of info on properly supporting plants over on the Growing Tomatoes forum here. Here is one of the many discussions about it running currently.

Tomato supports

Dave

I have plenty of room and home made cages but I still prune most of my suckers, I feel you get better fruit and less disease that way, But I plant enough tomatoes that I don't worry about losing a few, I don't cut the tips off, Sounds like you have some nice plants growing.

They aren't doing bad at all, other than all this rain we've been getting. It's causing the bigger fruit to start splitting at the top.

So you are using stakes, slender bamboo stakes, right? Yeah you are going to have to prune those plant heavily or they will just fall over. No choice there. Far from ideal for indeterminates so next year plan on a very different support system.

And splitting does go along with inconsistent soil moisture levels - either from heavy rains or over-watering followed by a dry period. And with a relatively shallow bed like it appears in the pics it will be difficult to get consistent soil moisture levels. Using heavy mulch helps eliminate that problem as it stabilizes soil moisture levels.

Dave

Last year I got lazy and just hung the vines from my fence (not bound to the fence but hung off it), and did no pruning. It worked fine. Kind of fun tying up all the branches too.

I started with bamboo but ended up getting 6' coated steel stakes then tied them up as well. The boxes are 18" tall but buried 6" and I dug another 2' down. I filled them with a garden mix soil I had trucked in. 7 - 4x12' boxes and used 20 yards of soil. I do need to mulch though. It also seems like the big beef are prone to splitting more than the pink cadillacs.

With regard to tomato pruning, I believe that there are some situations that make pruning healthy for the plant. Here in HZ10, life is rough in the summer. When my cherry tomato vines get eight feet long and longer, they have to suck water up a LONG way. The fruit way up at the top is seriously water-stressed. I have found that topping the vines encourages branches lower down on the vine that are closer to the soil. Now, that being said, once the lower vines are very mature, they aren't as likely to sprout new branches, but the new branches at least don't pop out way up at the top.

Not clear that this would be relevant to non-vining full-sized tomatoes. I've never pruned those.

Splitting tomatoes will only occur IF the plant is not consistently getting enuff water then you have a rain where the plant can get as much water as it needs and wants.

The moral of the story is IF you can't control the rain you need to control how much water you supply before the rain.

Plants feed from their root tips. Mature plants can have the root tips extend 4-5ft from where the stem enters the soil. I like to water my mature plants out in the pathway where the root tips are.

Not in the bed frame where they are planted. This means removing grass and/or weeds in a wide perimeter to avoid competition for water and nutrients. Where possible I prefer to have cleared and mulched a 4ft perimeter around my garden beds/frames.

<Splitting tomatoes will only occur IF the plant is not consistently getting enuff water then you have a rain where the plant can get as much water as it needs and wants.>

That's a bit too broad a statement for my comfort gumby. First because some varieties are much more prone to splitting and cracking than others regardless of the water consistency. Second because splitting and cracking can be caused just as much by the gardener over-watering and just as much by under-watering as by over-watering.

Dave

Certainly some varieties may be more prone to splitting - so are you saying that water does not play a role?

I don't think you can overwater a tomato plant - well maybe you can (if it was in a pot or clay soil) but that is NOT the cause of splitting it is because your plant is NOT used to taking in the water it wants and needs.

Said another way splitting is a sign of underwatering followed by overwatering - overwatering would cause the plant to yellow, not produce fruit, and die.

I have posted this link before - it is useful for more than tomato plants.
http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch26.html