The mildew you are talking about is probably algae. You can tell because of the green color. Mildew or fungus is often white or grey. It is not in the plants best interest to trim the roots because of the algae. The plant needs roots to uptake water and nutrition. You will be surprised at how slow the roots grow. That's a great choice of orchid for a beginner to keep in your house of apartment. Just keep it out of direct 10 am to 2 pm sun so it won't sunburn. I usually water mine inside every 4-5 days in the winter. As it gets warmer in the spring you will want to increase watering. Your goal is to let the potting medium just come up to dry before you rewater. Have fun with your new babies.

Hi Dave, Those silvery green talks are arial roots. They are very common on moth orchids - also called Phals or Phalaenopsis orchids. I wouldn't cut them off. Arial roots don't necessarily mean that the orchid is growing out of the pot. Phals are epiphytes - most orchids are. They use the roots to hang onto trees, rocks etc. If you get too many arial roots it could suggest that the plant isn't happy with the planting medium.(bark?) But if you have a new stalk - also called spike - covered in buds than it sounds like the orchid is doing well. After the last of the buds drop you may want to consider transplanting the orchid. It will give you a chance to see how the roots in the pot are doing and to move it to a bigger pot if necessary. Don't move the plant to a bigger pot if it doesn't need it. If it does need something bigger than only go one size up. Orchids don't like to be overpotted. It can cause root rot. This will also be the time to change the planting medium. Bark needs to be replaced every one to two years so it's probably starting to break down a little. (most suggest once a year for phals.) As bark breaks down it holds onto more water and this can also cause root rot if you don't give it a little extra time to dry between watering. You can search this web site for transplanting tips and for more information on moth orchids (phals). There is a wealth of information on it. I hope this helps.

The potting medium that you end up choosing should ultimately reflect your watering habits. If you tend to water sparingly, pot your 'chid up with spaghnum moss because it retains water/moisture a lot longer than other mediums. But since the issue has been root rot, I think it'd be better off in a fir/charcoal mix...something that allows better drainage and air circulation to the roots so they dry out a bit in between waterings. By using a more open medium like this, it will help prevent root rot from reoccurring. I use the regular "Orchid Mix" by Schultz, from Lowes or Home Depot and it works fine for me. Another thing you might want to consider is repotting in a clear plastic pot, because it allows you to look into the medium and better judge whether the plant needs watering.

Doesn't look all that bad. Old roots and leaves die. The potting mix is not some sort of pristine place. It teems with fungi and bacteria good and bad and as long as your growing conditions are favourable the plant will thrive. Where are you and what sort of temperatures, humidity and light is the plant getting and if you are in the north of USA will the plant get good conditions in winter?