Expert: Kenneth Joergensen - 5/17/2004

Question
Hi Kenneth,

I am a new gardener, and I have a few questions about bulbs. The first one is about Dahlia - not real bulb, but here it goes:
I live in Toronto (north part ¡V zone 5 hardiness). Last summer I planted a full growing and flowering Dahlia. A friend of mine suggested that I bring it in for the winter and store in peat moss, which I did. I started watering it in April and saw 3 shoots coming up. My plan was to divide them, but I did not ask anybody how, assuming that it would be intuitive. It was not. The roots were pretty hard, I broke one of the sprouts; I tried to break off another one, and managed it, but only with a relatively small root. I planted it anyway. And I planted the other 2 with the most of the roots together in a different spot. Now, the one with the small root seems to be broken by an animal or wind. Does it have a chance of growing again from that small root? And the other 2 don¡¦t look very good. For the future, what is the proper way of dividing the Dahlia sprouts?

Also last fall I planted Tulips, Daffodils and Irises. Since I was so impatient, I planted them too early, at the beginning of September; they started to grow last fall. They did ok this spring, but not as good as I expected. First of all, the number of Tulips that came back was much smaller than I planted. I heard that squirrels really love Tulip bulbs. Is there a way of protecting them? Second, only few Daffodils had flowers, even though a lot of them came up with leaves. They have these dry looking tops as if they were about to flower but ¡§changed their minds¡¨ ƒº. Irises simply have dry tops¡K Can you please explain to me why, and tell me if they have a better chance for next spring. (By the way, I did give them special bulb food when I planted them).

Thank you very much,
Oxana  

Answer
When you divide Dahlia tubers this is done by cutting the tuber in half so that each piece has an eye. an eye is what turns into the sprout.

the easiest way to divide tubers is to place them on a moist, but warm bed of peatmoss sphagnum, e.g. in a sunny window. this will "wake up" the tuber and red swollen buds (eyes) will appear. this will give you an idea of where the eyes are. you can then with a knife divide the tuber making sure that each devision has an eye. the divisions can then be planted. You can also dig up the tuber after sprouting has occurred and cut them, but you risk breaking off sprouts as you have noted.

Note: when dividing tubers, note that tubers have "neck" which is where the buds appear from. A potato in constrast will sprout eyes from the entire tuber. The dahlia tuber will only sprout eyes from the top piece of the tuber. the bottom part of the tuber is only food storage but has no meristem tissue (e.g. tissue capable of developing sprouts). This is reason I recommend "waking up" the tuber before starting to divide it.

Note: if you happen to break a sprout, the dahlia tuber will typically send up new sprouts provided it was plumb enough to do so.

tulips,daffodils and iris
I can not say for sure what happened to your bulbs, but in all likelyhood they grew too early last fall (planted in warm soil) and that depleted the carbohydrate storage which was responsible for flowering. especially daffodils are very sensitive to such.

dutch iris do not need a chilling period and they will usually grow foliage in late fall before winter. Most of this foliage may be damaged due frost in the winter. the foliage damage is seldom enough to kill them, however, and you may very well still get flowers from iris. they typically bloom in june/july.

I recommend that you plant tulips and daffodils in mid to late october in your area, after first frost. fertilize the tulips and daffodils now and again next spring. they should return and flower for you. do not restrict the foliage (green leaves). the bulbs need those to flower.

iris (dutch eg from bulbs, not rhizomes) can be planted in early spring which should limit foliage damage, or in fall in which case some foliage damage should be expected over the winter.

in any event, iris should flower in early to mid summer so do not be in a hurry to dischard them. we are in zone6 and our dutch iris has not flowered yet. they may not flower for another month.