Question
Hi!  I start a lots of annual seed every year and have great luck with most.  But growing annual Vinca is a challenge.  I have learned that it needs more warmth than most other plants, so I have the flats with Vinca covered with a dome and use a seed heat pad under them.it seems they are doing well each year until about this time when they start turning yellow. I use fluorescent bulbs for light, and add a little fish emulsion fertilizer to the water occasionally after they are transplanted to individual pots and are about 3 inches tall.  Would it help to use a foliar spray with fertilizer added to the water for the yellow ones?  Do you have any other info. that would help me with this problem?  I like to grow these because I can grow the vining variety that I can't find in the nursery or greenhouse.
I will be grateful for any advice you can give me on the subject of growing annual Vinca.

Answer
JoAnn, vinca is a sensitive plant to start from seed.  However, it can be grown successfully if a couple of procedures are followed.  

It sounds like you are doing all of the right things.  The seedlings need 14 hours of light per day.  The lights should be kept no higher than 3" above the plants.  I add a diluted solution (1/2 the recommended amount) to my water every 10 days.  I also add a small amount to my spray bottle and mist them twice per week.

Finally, do not overwater them.  This is the number one reason the plants begin to yellow.  Excess water depletes the soil of the nutrients needed for strong growth.  The soil should be moist, but never saturated.  Let the soil dry before adding water.

I hope this answers your question.  Good luck, and please write again if I can ever be of assistance.

Regards,

Mike