How big a container will you be using? You'll find some discussions here about the Topsy Turvey things and what a waste they are to use so a much bigger container is recommended - say a 5 gallon bucket minimum/

And if going that size - even larger is better - why not just grow it right side up as normal? You'll get much better results that way.

Either way I think you'll find there is no 'wasted space' as any tomato plant, even the small container type varieties, is going to need all the root room it can get in just about any container. Plus it will need all the nutrients and water you can supply so it doesn't really want to have to compete with other plants.

There aren't really any foods or herbs that would be helpful to the tomato plant in any way but if you really want something else in the same container then stick with a very small, low-growing shallow rooted herb.

Hope this helps.

Dave

PS: check out the California Gardening forum here for the best guide on planting dates.

Hanging basket , NOT upside down (!?)

Any small cherry type can be planted in hanging basket.
I have seen this 4 gal bucket at HD that is slightly shorter than 5gl bucket but maybe wider(!). It can make a good hanging container.
I have also tried that UPSIDE DOWN thing. It is just wast of time and money and it does not even look nice.

I would try to find a DETERMINAT type of cherry if there is one. There is also a currant type.

WHEN TO START ?:

When night temps stay over 50 F. Hanging basket plants cool down much faster than in ground plants at night. I can leave my tomato in the ground (without protection) at 43F. But not in hanging basket.

I'm in San Marcos. Do you mean you're going to start now or in the spring?

I figured I would use the top of the planter to grown something because why waste the space!

Wanting to plant something in the top of the planter implies an upside down tomato planter to me. If it was a hanging basket then it would be the tomato that was planted in the top of the planter.

Deeby - from what I have read from the So. CA growers planting there is much earlier than for most of us - like late Jan to early Feb. rather than in the spring. That's why I suggested the CA forum for best info on planting times.

Dave

I'd start seeds that early but if we plant plants they don't do well until we warm up and have longer days.
That may just be my experience though.
I've tried putting out tomato plants in April and they really struggled and never did well.