I would recommend any complete fertilizer in the amount and timing according to the instructions for the size of pot.

During the summer if they are outside you could use an organic fertilizer, but it will make your house stink if you use it while the plants are indoors in the winter.

Important: you will also need a "soil acidifier with iron" or something similar to combat chlorosis in the citrus. Apply it whenever you start to see some yellowing between the leaf veins. This might amount to twice a year or so.

Lastly, you might check out the citrus forum, where there are loads of knowledgeable people growing citrus in containers in colder climates.

I would highly recommend not using organic fertilizers in container culture.

Containers typically don't support the bacterial/fungal culture necessary to break down the fertilizer. Too many temperature/etc swings.

Something in a 5-1-3 ratio is best.

I'm a bit concerned with the "maybe only 6" tall," as edible citrus are typically grafted to dwarfing rootstock at a much larger size than that (usually pencil thick, and a foot plus tall), and it means you may have seedlings

Yes. my "trees"are seedlings. I am hesitant to use a lot of chemicals due to my very curious and acrobatic chihuahuas who really enjoy eating out of my planters. Are the miracle grow citrus spikes ok to use? Should I wait until they're bigger to fertilize them?
The seedlings were described as tabletop citrus. i am aware that more than likely these trees are ornamental and will bear little fruit and if they do it will be several years out.

JoppaRich,
I see what you're getting at with the caution against organic fertilizers in container culture, but that's mostly just conventional theory. In practice, many of us get wonderful results with organics such as fish emulsion, just not at the speed or exact NPK numbers that the chemicals provide.

Crab - I had some citrus seedlings. Out of some key lime seedlings and some lemon, I only have one lemon left. They do not like to dry out at all, and the seedlings seem to like less sun then they would when they are older. It is doing way better in my shaded greenhouse, then it ever did outside.

Most potted plants (well say house plants) in my experience seem to do ok with some neglect, as in no fertilizing for a while, but citrus seem to really need it, in my experience. They seem to start to decline and turn a pale yellow, rather then the nice deep green. They usually need a good amount of micronutrients, most citrus fertilizer or potting soil has these in it. The one that comes to mind is citritone (which I cant get up here :( )

pommagranetes seemed to do quite well in pots, but i killed mine after not watering it for a month (the downside to having a few hundred house plants) Even if it doesnt do well, pomms are amazingly easy to start from seed, and one pomm will give you hundreds of seeds. Again, they seem to need a bit less light then they would as more mature plants in my experience.

Just a note - Fruit trees are a hit or miss when growing from seed. Sure, you will usually get something desireable, but for the most part, they will not be and exact copy of the parent.

that being said, If the lemon was grown from a "regular" lemon type, you have a good chance of it being quite similar to the parent, if it was a meyer, then most likely not.

If the lime seedling was a key lime, then it should almost every time come true from seed. Im not sure about the other limes, but if they are polyembryonic, then they have a good chance.

Oranges are usually pretty close as far as ive read, but it also depends on the parent as well..... Worse comes to worse, you can try grafting a desireable type when they get older.

"Just a note - Fruit trees are a hit or miss when growing from seed. Sure, you will usually get something desireable, but for the most part, they will not be and exact copy of the parent."

The vast majority of citrus produce nucellar seedlings that are identical to the parent, so thats not a huge worry here. There are of course exceptions, like you said, but generally you need to try to hybridize citrus.

The problem is that citrus decide when to fruit based on node count-IE, they fruit when they are so many nodes from the original node. Its going to probably take a decade for fruit, and if hes pruning it, it may never fruit. If its a key lime, it'll fruit in a couple years, as long as you let it grow, and don't prune it to keep it small.

As to fertilizer, fish emulsion works fine. Its not going to work any better than a synthetic though, and it smells terrible. Stay away from compost or anything like that though, its a recipe for a soggy mess.

Everyone has given you very good advice. First, you're probably better off over on the Citrus Forum for this thread. Most container citrus folks use a great product called DynaGro Foliage Pro. Organic fertilizers are turned into inorganic compounds by soil organisms that allow the plant to absorb the nutrient, so I'm not really worried about organic vs. inorganic, as it all ends up being the same thing. And, in the amounts you're applying it isn't going to be an issue with your dogs. In fact, one of the reasons I don't use bloodmeal in my yard is because it ATTRACTS my dogs (and other animals I don't want in my yard). So, up to you. Foliage Pro has a very good NPK ratio for citrus, plus as importantly, all the micronutrients needs. And I confess, I've never heard of "tabletop" citrus trees.

Patty S.