Q. I have a question about persimmon trees. I bought three pairs over the past several years from a well-known mail-order company. They were supposed to be one male and one female. All of the trees have little bell-shaped blooms, but don’t develop fruit. Have I received all females? How can you tell the difference? The oldest trees are over 10 years old. How old do they have to be to bear fruit?

A. While it can take seedling persimmon trees 10 or more years to mature enough to flower, your trees appear to be ready. If the trees are blooming, then they are old enough to bear fruit. Assuming that all of your trees are American persimmon rather than Oriental, then the issue is whether you have a mix of both male and female trees. (It would be useful to know what cultivars you have planted.)

American persimmons usually bear separate male and female flowers on separate trees. Only the females will bear fruit, but you do need to have at least one male to provide pollen for fruit set on the female trees. Occasionally, persimmon trees will bear both male and female flowers on the same tree, but it is not the norm.

So if all of your trees are blooming, then the question is whether you have both male and female trees. When they bloom next year, look closely at the flowers, and you should be able to tell them apart. Both are greenish-yellow, bell-shaped flowers borne on very short stalks. The male flowers are about one-fourth to one-third inch long and are borne in small clusters, usually in threes. The female flowers are slightly larger, borne singly and are about one-half to three-fourths inch long.

This year, it is possible that the flowers were injured during the April cold snap, rendering them unable to set fruit. Let’s hope for better luck next year!

Q. My potatoes are producing little green tomatoes. Does this mean they cross-pollinated with my tomatoes? Will these fruit turn red when they ripen and will they taste like tomatoes?

A. Actually, those are the normal fruit of the potato plant — a relatively unusual occurrence in Indiana. It’s not surprising that they look like tomatoes, since both plants are in the nightshade family. However, potato fruits are typically high in solanine, a substance that is toxic to humans, particularly children. Potato fruits should not be eaten, no matter how much they look like little green tomatoes!

Cool temperatures during long days tend to promote fruiting in potatoes, which explains why many Indiana gardeners are noticing them this year. Also, some cultivars seem more prone to fruit formation than others. So your potatoes may be fruiting while your neighbor’s may not.

Q. My ‘Endless Summer’ hydrangeas have yet to begin blooming this year. I haven’t treated them any different than last year, when they bloomed beautifully. The plant has lots of nice green leaves but no flowers. Is there something I should do to help them?

A. Don’t give up on the plants yet. Mine are still not blooming either, but I expect they will come on in the next few weeks. ‘Endless Summer’ blooms both on old wood, if those buds survive winter and spring frosts, as well as on new wood, usually beginning in mid to late July. I suspect most plants were killed to the ground in the April cold snap (mine were), so that would result in blooms only on new wood.

This type of hydrangea likes warm temperatures and moist soil. We’ve actually had a relatively cool and dry summer for the most part, with many nights below 60F, so perhaps that has slowed down the formation of new summer flower buds. The good news is that once it does start to bloom, it should keep on flowering until fall frost.