HelpfulGardener.com

Hi All,

I am new to this forum. I hope it is better than the last one I tryied. I never got a response there.

I am a novice gardener that loves to have flowers on the deck in the summer. We live in central MN and the growing season is so short that we need to add color fast and keep it as long as we can. (Mn only has 2 seasons, winter and the 4th of July). One of our favorite flowers are dahlias and we buy vibrant colored ones at the local nursery as soon as they open, (May 1st), and put them out as soon as the frost warnings are gone. They look so beautiful throught the first bloom, but the second set of bloom always turns yellow and rot before they open. The rest of the plant stays green but that is all we get for the rest of the summer. We keep them in a large pot on the front deck in a partial shade location. Any ideas on what we are doing wrong. All the other annuals that we put out stay looking great for a months.

Also, When our petunias start to get leggy, can we cut them way back to have them branch out for more blooms???

Thanks for your time,

Howard

Could be rot (fungal disease), but I suspect thrips. Look for small holes in the underside of the bud; thrips chew in and eat the inside of the bud killing the flower and not allowing it to open (what you see as rot is a symptom and not the problem). Orthene is a systemic insecticide that is usually recommended, but it is less effective on chewing insects. Thrips are also a big problem for roses, so if you've any of them, you might want to treat them at the same time (no sense in moving the pest from one plant to the next). Expecting a second set of blooms as far north as you are is asking a lot, you know; could you just be getting too late in the season to support the flower?

Scott

I tend to agree with Scott about the rot. Dahlias like full sun - 6 hours or more. Take a look at this site for info on growing dahlias.

https://www.ces.ncsu.edu/depts/hort/hil/hil-8500.html

I would suggest you gently look at the tuber in the soil to see if rot is the problem before you use any pesticides.

Newt

Newt's right; look for those chewing holes on the underside of the bud before you spray with Orthene; it could be a simple fungal problem, but I know dahlias can be prone to thrip attack, so definitely check that out...