Is that a raised bed or a large container? If a raised bed, is it closed on the bottom (except for drainage holes), or do the roots have access to go down into the regular soil? What is the mixture inside the container?

There are multiple issues with your watering strategy, but I don't think that would account for the poor growth seen there.

I think Jean is correct to ask about light. How many hours of direct sunlight do they get per day?

Hi! It's a raised bed, not closed on the bottom. I used some garden soil specific for raised beds (not sure, but I believe it's Miracle Go).

About the sunlight, I'd say it gets around 4-6 hours, not more than that, but it's still a guess (as I've never really counted them, and chosen the sunniest spot instead)... I'll try to improve the lightning with some aluminum foils. pls let me know if you have any other idea.

I really appreciate all your help. Thanks!

Where are you located?

New York City

4-6 hours of sun is low. The rule of thumb is at least 6 hours of direct sun a day for tomatoes. But even plants that get 5 or 6 hours would grow vegetatively (stems and leaves) more than what your plants have done. I would guess from the way they're growing that it's toward the lower end of your estimate, possibly lower.

But since we can't move the sun, maybe try to adjust some other things. First, watering in-ground plants 2x a day is no good. If you are watering a little bit 2x a day, then you are encouraging shallow root development, and the plants may not get enough water, since the water stays on the surface and evaporates off. If you are watering deeply 2x a day, you're almost certainly overwatering and drowning the roots. Go by how much water is in the soil. Dig down and see what the moisture level feels like a few inches under the surface before you water. Nature doesn't follow human schedules, and no set watering schedule will account for rain and humidity and the plant's moisture needs. If the soil is moist down in the root zone, then you don't need to water. If you do need to water, water very deeply, i.e. give a lot of water at a rate that is slow enough for it to go down into the soil and not run off. Less frequent, deeper waterings are better for tomatoes. This encourages plants to develop a deep root system. In NYC, if you have plants that are in the ground with well established roots, you shouldn't need to water more than once every 3 days, even if it's been hot, unless you have a yard that drains bizarrely quickly (which is possible--lots of weird stuff can happen in urban yards). With the size of your plants, maybe check soil moisture every 2 days, as it's definitely possible they don't a have a big root system.

For fertilizing, ditch the spikes. They just don't work well. Miracle Gro is OK for now, although you will need a fertilizer better balanced for fruiting plants later if you can get your tomatoes to that stage of development. Are you following the directions for use?

Hey, I'm in NYC as well. My tomato plants are in containers (no green space). Given the hot weather and heavy rain about once a week here, I feed them about every three days.

Have you considered amending your soil with used coffee grounds and using epsom salt in your water.? Or adding some mulch? I get my mulch from Green Wood Cemetery where they maintain a free pile. As for the number of plants, instead of three plants, plant one inside that cage.