Question
I have grown plants (vegetable and flower)from seed for several years and have learned a lot but still have much to learn. Several questions - Some of my seedlings (vinca and zinnia) have leaves which are turning brown. I only bottom water these and only when dry. I am fertilizing once a week. I make sure they have at least 16-18 hours of light every 24 hours.
Secondly, last year I cut the tops of my impatiens because they were growing quite large before the weather was okay to set them out. I rooted those and they did very well, which doubled my investment. However, my plants did not produce as many blooms as they had in years past. I realize many factors could be to blame, but was I wrong to snip the tops. Also, could I do that with the vinca I am growing this year.

What makes the soil in the flats turn green on top? Should I do something about it?

Thanks so much for your answers.
Jaye

Answer
Hello Jaye! Thanks for writing!
For your seedlings, I would make a few changes: your watering system is great; most people overwater because they feel they're neglecting their seedlings if they don't.  But, try this with your fertilizing regimen: dilute the fertilizer by at least one half and feed half as often.  Or, better yet, use this tried-and-true seedling fertilizer
for faster, healthier growth:

1 Tbl. liquid or dry kelp/seaweed (save money by going to a health food store and buying powdered kelp. It's very inexpensive. Just mix it with water until it's the consistency of thin buttermilk.), 1 tsp. Blackstrap molasses, 1 Tbl.willow tea, 1 gallon of water. (The willow tea is made by taking a twig of willow - any kind - and cut it into 1 inch bits.  Soak it in boiling water for a couple of hours or at least until it cools completely. Strain out the twigs.) Put the fertilizer into a spray bottle and spray the plant's leaves, both top and undersides. You can water your seedling with this mix, as well.  The kelp has high amounts of nutrients, natural plant growth hormones, trace minerals and has been found to make plants more pest and disease resistant. Willow contains natural plant growth stimulating hormones. The molasses contains iron, sulfur and simple sugars which nourish the plant.

The green on the tops of the soil is mold/moss.  You may notice that you have a few little gnats buzzing around, too. Anyway, to get rid of the green mold/fungus/moss, you can sprinkle some dry powdered peat moss on top of the soil.  If you notice any die-back of seedlings, called damping-off disease, make a strong couple of cups of chamomile tea. Cool it and dilute it a bit - cool it to room temperature. Put it in a spray bottle, and spray your seedlings. Then, make the same stuff and use it to water them when they need it. It strengthens them when they are at their most vulnerable.

As for your impatiens, trimming them will have only made them thicker and flower more prolifically.  Let your plants have 12 hours or a bit less, for light per day.  Plants need dark as much as light - it's when they do thier actual growing. They spent all the light hours photosythesizing and storing sugars/nutrients. Darkness is when they can slow down their fast-paced photosynthesizing, and finally get to relax and use those nutrients and grow.

Hope this helps,
Eirinn