It pretty much always means inadequate light.

No the seeds aren't to old. If they were to old, the seeds just wouldn't germinate.

Legginess is caused by two factors, insufficient light and lack of movement. To correct the light issue you either need to get to get a stronger light source or if you are using grow lights move them closer to plant level.

Most people over look the motion issue. When plant are grown outside they are exposed to movement caused by wind. When they are grown inside ther is no wind. so if a couple of times a day you gently brush the thop of the plants with your hands they will actually not grow as tall.

When it comes to impatiens legginess can be looked at as a bonus. You can cut back the plants and root the cuttings to you get. So it is like getting more plants for free.

I agree with previous posts that legginess is almost always due to too low light. I recommend that you grow the plants in a sunny window or - better - under fluorescent lights. Do not use incadescent lights (pear shaped bulbs). Fluorescent lights are best.

If you are using a window to grow the plants, then make sure it is a sunny window and turn the plants daily so they do not bend to towards the light.

I actually prefer to put them under fluorescent light indoors. This can be done by buying an inexpensive "shoplight" at home depot ($15-20 for the fixture) and fit 2 x 40W cool white bulbs in the fixture.
Hang the fixture so that the top of the plants are almost touching the bulbs, or atleast no more than 3-6" below them. E.g. keep the light fixture suspended just above the canopy of the plants.

As the plants grow, you can/should adjust the light height (typically you raise it by using the supplied chains).

To help you visualize this, I have posted some pictures which you can view below:

(obviously, you do not need to build a wooden stand as shown in the pictures. You can just hang the shoplight using the chains from a board, an overhead shelve, etc).

A few notes:
- when you keep the plastic dome (cover) on top of your seeds, do not place the shoplight too close to the seeds (as shown in my pictures.. a bit misleading). This will cause the temperatures inside the dome to rise too much. When using the domes/plastic covers then keep the shoplight about 12" above the dome.

- once you remove the dome/plastic covers, then you can adjust the height of the shoplight to be just inches above the plant tops.

For Flash version of slide show

Click here: Flash version of slide show"

Slideshow with text advice

You can also click here and then click the blue "slideshow" button instead. This will give some small pieces of text advice, too.

Or you can click on the individual pictures below:

Buying and Installing Flourescent Lights for seed growing

I agree, it's a light issue. If you are using lights, get them within a couple inches of it. If you are using a window, make sure to turn them everyday. With a window there is not much you can do about inadequate light but you can minimize it by turning.

After they get a few true leaves, start pinching. They respond well to it and you'll have nice bushy plants.

Last year, all of mine were leggy...started them in a sunny south window. When I took them outside in the spring for potting up and hardening off. When I potted them up, I buried the stems up to just below their first set of leaves....

Worked like a charm! Didn't lose a one and they were sturdy and happy.

Of course, I am only Winter Sowing this year so that won't be an issue.

Thanks for all the info. I will correct and hope for a good planting season!