herbicide

does anyone have experience with herbicides and bulb and tuber plantings? We have used a pre-emergence on our dahlia, tulip and daffodil beds. Last year we did not have great dahlias, in fact some were disasters. We originally thought they may have drowned in wet soil but now wonder if the pre emergence may have had something to do with it. 6 years ago we had the most gorgeous dahlias with not one bad one, out of about 50. They seem to get worse every year??????????????????

Do you leave your dahlias in the ground over winter then? The dahlia forum suggests that they need to be dug and divided every 3 years or so to keep them in good shape even if your winters are reliable. Hart grows hers successfully without doing that though.....I don't use herbicide so I can't really help with your main question.

Yep, I would guess the cold or rot would be a lot more likely to have gotten them than a herbicide. I leave my dahlias in the ground but only in a very protected bed right next to the house. You should lift them to be on the safe side.

Wet soil is really bad for most bulbs and tubers too. Like dayli, I don't use those pre-emergent herbicides so I don't know what effect they would have on bulbs or tubers. I would guess none. You might want to ask about this in the dahlia forum.

Yes a preemergent can have potentially devasting effect on tubers and bulbs.Especially in unestablished plantings[just planted this year].Generally its better to hand weed.Its also ok to use a hand cultivater[this might not be the right name for this]It looks like a set of intertwining tines.Once your plants have established it may be ok to use a herbicide if weeds are still a nuisance.Really it matters more whats in it.Check to see if its rated safe for flowers vegtables.Most herbicides that can be used on vegtables can be used on flowers.Not all but most.

I'm with centrlva, I avoid herbicides entirely, and I think I persuaded my neighbor not to use the lawn pre-emergent near my flower bed, but Dahlias will tolerate many herbicides, and not others. I think Surflan is one you're not supposed to use around Dahlias. Beleive it or not, research is being done to genetically alter Dahlias (and other plants) to tolerate herbicides. These links show which herbicides Dahlias will tolerate.
Hopefully...

http://edis.ifas.ufl.edu/WG062#TABLE_3

http://209.85.165.104/search?q=cache:xccQiZMiuGcJ:edis.ifas.ufl.edu/pdffiles/WG/WG06200.pdf+dahlia+herbicide+tolerance&hl=en&gl=us&ct=clnk&cd=19

edit: In the second link, Dahlias are near the bottom of the page

This message was edited Jan 25, 2007 3:49 PM