One of the biggest gripes you'll see on this forum is about the false labelling of plants and seed-packets. You don't always get what it says on the label. There are many different species and cultivars of basil. You've probably got a basil, but perhaps it isn't the one you expected! This in itself isn't a bad thing, if you happen to like it, of course.

Never allow potting mix to dry out completely. Apply the finger test. Poke a finger into the soil as deep as it will go. If the tip of your finger remains dry - water the plant. If it feels moist and cool, wait another day.

Basil actually likes plenty of water, but like so many of the popular culinary herbs, you must provide excellent drainage. Any plant in a pot will need more water and more fertiliser than a plant in the garden, where supplies are more replenishable and available. Potted plants are high-maintenance.

A full-grown basil can get well over 1 metre tall (mine get to more than 1.5 metres, here in the subtropics), and wider than that. Imagine three of them crowded into one pot! Well, you might get away with it if you've used a bath-tub as a pot, I suppose.

You don't mention the size of your pots, but as a general rule I put only 1 plant per large (40cm or more) pot. Herbs can get bigger than most beginners even imagine. Any potted plant will be stunted to some degree. If the roots are squashed or bent, the plant can't access the food and water it needs - plants need room to spread, both under the dirt and above it.

I am going to start my basil from seeds this year (I usually buy the Plants). Is it too early to start them for a Memorial Day transfer to the outside?

Mike 63, yes, in your zone I would sow them indoors now. Basil will take 10 to 20 days to germinate. Then I would want them to have 6 weeks minimum growth time before putting them outdoors. So mid-March is not too soon IMO. I have two week old basil seedlings indoors now and I will probably pot them up to bigger containers once or even twice before introducing them to the outdoors.

Your information about Basils is quite less than required. Are you growing them inside and in a container.
If you are growing them inside, you will have to take a lot of care of your soil. The soil required for successful basil growing indoors must be moist and it should not be soggy. Therefore you must acquire a pot with an adequate drainage; otherwise the roots of your basil plant have a great possibility to rot.
If you want to get good results, the basil plant must be planted in a terracotta herb pot. For this you will need the following:

Organic/General fertilizer
Terracotta Herb pot (much more like a strawberry planter)
Potting Mix
8 Basil plants of different variety

I hope this will be enough information for you. If you need to ask something else, do provide with detailed information for your problem.

Mike63, while I do start seeds each year it's only the stuff I can't direct sow with success. I direct sow multiple kinds of basil each year with great results. If you start some indoors now, save some seed for direct sowing as well. That way you'll have basil maturing at different times in the garden.

FataMorgana

You might try dwarf greek basil or globe basil. They are much more suitable to pots.

Any plant will grow very tall and gangly, but have few leaves, if it doesn't get enough light. I think that if your basil gets enough light next time, it will be bushier and have more leaves.

Many of the plants of all kinds that you see with lush growth in the stores have been over nurished and trimmed to look good in the store. Many times once you get the plants home they will have a difficult time adjusting to regular growing conditions. Most gardeners don't have a table spray system that sprays the right amount of fertilizer and turns the lights on for maximum effect.

JennHutch, I may be on the wrong track here but thought I would mention this. To get full, lush basil plants you need to harvest it regularly. Cut sprigs of it, not just leaves. Usually, for every sprig cut, three new "branches" will grow and it becomes a fuller bush like plant. (Others may have different experience with basil) If only leaves are cut, the plant can grow tall and spindly.

I grow some herb combos in containers. Smallest container is 20" inside diameter. For example, I have sage, chives and rosemary in one. In another, I have thyme, chives and oregano. You have to keep the plants pruned so they don't grow too big. I use lots of fresh herbs so it's not a problem. I grow basil in dedicated containers. Basil forms big dense root systems and I think would choke other plants. If the containers are big enough, keeping them watered is not a huge problem.(Again, my experience only). They absolutely must be in containers that provide good drainage. Most herbs will not do well and many will die if they are waterlogged. For me this means not using the saucers for the containers. Let them drain freely. In summer, I water the containers daily. As long as you have potting medium and a container that drains well, you probably should water daily. All that watering will wash nutrients so remember to fertilize as well. Hope this helps.

An alternative to starting basils from seeds, is to get
some nice and fresh bunch of basil from a farmers market
type of store (H-Mart, Asian markets) and root them.
Last year I did that with Thai basil. It worked.

The nice part about seeds is the variety - you can get seeds of varieties you'll never find in the grocery markets. The basil seeds I get and grow each year are for various heirloom varieties including my favorite which is "Siam Queen," a thai basil variety.

FataMorgana

jennhutch, it wasn't clear to me from your post whether you were growing inside or outside. Basil loves sun and will get all leggy and gangly without enough light. If you're trying to grow it indoors you will probably need plant lights if it's not in a south window with LOTS of light, and maybe even then to supplement. If it's outside it wants to be in full sun. Ours thrives here in our horribly hot summers in a space with no shade at all, given enough water.

As Opal52 said, you MUST trim/harvest your basil regularly to get a good-looking plant.

Last year, I had four little basil plants growing in about a 10" terracotta pot and they did fantastic. The secret to basil is that it's like a hydra: if you pinch off a branch, two more grow in its place. (Lots of other plants are like this, too, for example jade tree and even other herbs)

When you harvest, don't just take a single leaf off the side. That's effectively starving it, because you leave the same size body (stem) but take off its food supply (from the leaves that catch energy from the sun). That really hurts.

Better is to pinch off an entire stalk right above a node. A node is the place on the stem where a plant branches. In basil, you will see two leaves coming out on either side of the stem, and the stem continuing up. Pinch off right above where the two leaves branch out, and take the entire stem and leaves above it. Early in the season, this should be plenty to make some pasta or something.

When you do this, your plant is left without its old growing tip. However, it's still trying to reproduce (the entire point of life) and in order to do that, it needs to get bigger and produce flowers & seeds. It has lots of big leaves down low still, so what it does is to just send out a new growing tip -- or actually, two.

A few days after you pinch off a stem right above a node, you will see two new stems developing right where the leaves connect with the stem. In a week or less, there should be enough new stem on each of those to harvest a bit, and get it to split again.

You see the utility of having four plants in the same pot: they all fit nicely, and they give you lots to harvest. As soon as you start getting three or four pairs of leaves on a plant, you can pinch it down to the bottom two or three pairs and have some early basil. Harvest like this from all four plants and you've got plenty to cook some nice pasta or something. Two weeks later, you've got eight new stems to harvest (two from each plant), and you can make two or three meals from these if you don't harvest all the stems at once. (Make sure to leave new nodes above the first branching so it keeps branching) A week or two after that, and you have 16 stems to harvest. Et cetera.

By the middle of the season, you can be harvesting enough basil leaves every week to make a bunch of pesto, and your plant won't even be hurt by it.

That (and having full sun and regular watering) is the secret to growing good, productive basil plants.

Also, PLEASE plant more than one herb in a container! It's awesome!

Last year I had three long pots each with three herbs: one had parsley, savory, and oregano, one had lavender, sage, and thyme, and the third had marjoram, spearmint, and something else that I can't remember. From just those three pots, I had so much delicious fresh herb that I couldn't eat it all. (Actually, those three pots, about 4 square feet of soil or less, gave me plenty of each herb to not only eat fresh all summer, but also make two harvests mid-season to dry and use all winter!)

So do it, and grow lots of herbs!

I'm also growing basil in containers, but I failed to measure my pot. I only found out that my container was sized 6". The seedling container that I bought had 3 seedlings in them. I had to sacrifice one small seedling and the other seedling was transfered to a 4" container. My problem is there is something growing in the leaves. I don't know what it is, but it is making a snake-like burrow within the leaves that has a golden sheen to it and a black margin. I sprayed my basil with fish and seaweed emulsion. Any tips to control this burrowing pest?