Question and Answer - Indiana Yard and Garden - Purdue Consumer Horticulture

Question and Answer

Q. I have two wisteria bushes that I planted alongside each other about 10 years ago, and either has yet to bloom. One is white and the other is supposed to be red. Do I need to have a female and male plant, as you do bittersweet, in order to produce blooms, and, if so, how do I know which is which?

A. First, wisteria do not have separate male and female plants, but even if they did, this would not affect flowering, only fruiting. Wisteria are notorious for taking up to 15 or more years to become mature enough to bloom. This — and the many other reasons why they might not bloom — is addressed in

Q. I have a pink magnolia tree that drops the flower cluster just before the bloom opens in late summer. It’s been three years since we purchased it, with the same results every year. The tree is about 10-foot tall and appears to be healthy.

A. That is a bit of a mystery, as magnolia typically flower in early to mid spring rather than in later summer. Occasionally during unusually cold weather in summer, a few flower buds may develop in late summer and open for bloom. If it drops the buds just before blooming in spring, it is likely due to spring frost and freeze injury. Some magnolias will open their frost-injured buds to reveal browned petals, while other buds will just drop without opening. Some selections are more prone to frost injury than others, so if yours is consistently doing this, you might consider moving it to a more protected location or replacing with a hardier cultivar for your area.

Q. I have a small lake/pond where I would like to plant two or three bald cypress trees along one corner of the shallow end. Can you advise me about the planting necessities, for instance, planting in the water or on the bank? I would like the above-ground root development, if possible. Or is this type of tree just not hardy enough for this area?

A. Bald cypress, known botanically as Taxodium distichum, is considered hardy in most, if not all, of Indiana and although a needled conifer, it loses all of its leaves during the winter, growing a new flush of leaves each year. Bald cypress prefers moist, well-drained soils but are well adapted to flooded, swamp conditions. It is at the edge of the pond or swamp where they are most likely to develop “knees” — the knobby, low-growing protrusions from the root system. Knees are less likely in deep water or drier soil.

Q. Some of our tulip trees are losing their bark around the bottom and goes clean around the trunk. Can you tell us why, and will we lose these trees? They are about 18-19 years old. One is losing a lot of leaves.

A. It’s hard to say for sure, this could be damage from rodent feeding or repeated weed whip or mower injury, but my money is on the rodents. Deep trunk injury that goes down to bare wood and involves a large portion of the circumference of the tree is likely to result in substantial root and branch dieback. There’s not much you can do to help this damage now, but you can prevent further damage to this and other trees by keep vegetation and mulch pulled back away from the trunk. Fine metal mesh hardware cloth or commercial tree wraps can be applied temporarily to prevent feeding during the winter months. You’ll need to insert the mesh several inches below the soil line and at least a foot above, perhaps higher if rabbits and/or deep snow are an issue. Remove the mesh or wrap in spring to be sure the trunk has room to grow.

Q. I have planted at least a dozen different varieties of tomatoes in the two years that we have lived here, including brandywine, big boys, better boys, beefy boys and several others. This year, at the end of July/beginning of August, I had a volunteer come up. My wife and I are disagreeing on whether this volunteer plant came from last year’s garden or this one. My father-in-law agrees with my wife and says it had to have come from one of last year’s tomatoes. He said that the seeds have to go through a freeze before they can grow.

Also, we had a tomato bloom this year that looked exactly like a dandelion. Is it even remotely possible that this was a cross pollination between a tomato blossom and a dandelion, or just some kind of deformity, possibly from too much nitrogen?

A. By now you must have learned that you should never argue with your wife AND your father-in-law! The volunteer seedling is most certainly from last year’s fruit. Particularly since it was such a cold early season this year, it is unlikely that you could have produced fruit ripe enough to have mature seed by end of July this year. Tomato seed does not need to go through a freeze in order to be capable of germination, but it does need to be physiologically mature.

I have learned to never say “never” when it comes to plants and Mother Nature, but it is quite unlikely, if not impossible, for a tomato to cross with a dandelion. However, it is not all that unusual to sometimes see a distorted tomato blossom that has an extraordinary number of flower parts. This distortion is referred to as fasciation. More information is available at

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