What and how often have you been feeding it? Nutrients leach out every time you water so you have to replace them regularly. So it could easily need feeding. Small containers like a 5 gallon bucket may need feeding weekly.

How well a plant will do in a 5 gallon bucket, how long it will take it to get rootbound, all depends on the variety/type. So what is your plant?

While it is true that most plants have really long roots it is also true that they can get rootbound at the same time. The only way to know is to carefully try to lift the plant out of the bucket when it is fairly dry. If the whole ball lifts straight out it is rootbound.

Sometimes with a 5 gallon bucket you can cut off some of the bottom and set it on dirt so the roots can grow right on into the soil. Not an idea solution but it lets the plant live somewhat longer and it doesn't have to be watered as often. Or you can set the bucket into a tray of some kind and water it from the bottom.

Dave

I have most of my tomatoes in beds except 5 in containers about 5 to 7 gallon. I feed them every other time with liquid fertilizer (Added to water in watering can) at about 1/3 strength. No problem. They are doing fine, I figure if the have filled the container with roots that is already too much root they needed in the first place. Now all they need is moisture and food.

Here is a picture of one:

my apologies on what type of tomato plant it is. I was having wiFi issues the first time I was trying to enter it all in and got frustrated.

it is a cherry tomato Sungold indeterminate.
Soil ratio is 15% compost/top soil mix. The soil is still very rich.I just planted this a month and a week ago. It has about 50 tomatoes on it right now.

Soil ratio is 15% compost/top soil mix.

That may be your issue right there. Top soil in a container is notorious for being problematic and causing drainage problems and root rot which is why only soil-less potting mix is recommended for use in containers. And if that initial dose of compost is the only source of nutrients then your plant is quite hungry.

Compost only works as a source of nutrients IF there is an active soil food web in the container to digest the compost and provide the nutrients. Basic law of organic physics. :)

Within a week to 10 days of watering and plant growth those nutrients are gone and must be replaced. How you do that is your choice. Granular organics are slow acting, liquid organics are faster but need more frequent replacement, synthetics are the fastest acting.

Organic gardening in a container is a whole different ballgame from gardening organically in the ground.

Sun Gold is a huge plant. I have one growing in a 25 gallon container and it is already almost 7' tall and easily 4' wide and has hundreds of fruit on it. It is in organic potting mix mixed with composted manure and I still have to feed it weekly with fish and kelp blend liquid fertilizer to keep it from yellowing simply because it has to be watered so much more often than if it was in ground. Your 5 gallon bucket has to be watered much more often than I have to.

Feed your plant or it will start dropping all those yellow leaves.

Dave

This is the first time I have ever heard anyone else say Greetings and Salutations ! I use it all the time for fun. You get major points with me, Chad ! LOL !

Wow! I must've read over the size that that it gets.I wouldn't have bought the plant. well too late now. My yard is pretty small.
I would like to stay organic with the plant, what would your recommendation be?

So even though this yellowing happened in a matter of 5 hrs, your saying it is a nutrient deficiency?

I think it is a nutrient problem. The soil needs food, but you might also try foliar feeding to give the plants some quick help.

I'm transplanting it this morning into the ground. I did some rearranging and made room. Hopefully that will help out.

So even though this yellowing happened in a matter of 5 hrs, your saying it is a nutrient deficiency?

No, I was saying it is a combination of issues but leaving it in the bucket filled with topsoil feeding was the only one you could fix.

By transplanting it into the ground, assuming it survives and bounce back will help. But you will still have to feed it.

I would like to stay organic with the plant, what would your recommendation be?

As I said above, one of the fish/kelp blend liquid supplements works well.

Dave

I have a theory :
I think you can even pot with/in garden soil provided:

-- It has adequate drainage and porosity.
Medium has a role, that is to store right amount of moisture and nutrient.

You can do this by adding perlite and pine bark fines, for example, to it.
As I have read, plants roots also need air (Oxygen). So the problem with garden soil in small containers is compaction and with that comes lack of air, unless it gets real dry.
Plants can take much water provided with that also comes oxygen.