Ask Mr. Smarty Plants

First, how nice to hear from someone in England. We may not be much help to you as the Lady Bird Johnson Wildflower Center is dedicated to the care and preservation of plants native to North America. So, we're going to suggest you follow the same practice of using plants native to your area. Regardless of where that is, native plants will always do better with less maintenance because they are already adapted to the area and have developed survival techniques over the millennia. However, we are gardeners, too, and are always happy to talk about plants, so we'll see what we can find out for you.

Searching for "Mountain Ash", we first discovered that there is one in our Native Plant Database, Fraxinus texensis (Texas ash) . It is a member of the Oleaceae (Olive) family, and its native distribution is Central (where Austin is) and North Central Texas. We're pretty sure that's not what you have. Next, we found out that in Australia many common eucalyptus trees are referred to as "ash" and that the best-known of these is the "Mountain Ash," the tallest broadleaf tree in the world. That's probably not what you have, either. We found that the European common ash is Fraxenis excelsior, also in the Oleaceae family. Sorbus aucuparia, an European native sometimes called a mountain ash, is most often referred to in the UK as a Rowan or Whitebeam, except that in the UK it's referred to as Pyrus aucuparia. These last two are both in the Rosaceae (rose) family, and most likely are what you have.

We went through all this exercise hoping to narrow down what tree you have so that we could help you determine a way to eliminate the seedlings in your garden. And, guess what? It's just the same as any other tree, although perhaps more prolific. Any herbicide you tried to use on those seedlings would only harm other valuable plants in your garden, including the mother tree. They may be actual seedlings or they may be sprouts from roots, or both. If you remove the flower before it seeds, that would at least cut down on the seeds on the ground, but in a tree, that could be a challenge. Keeping the ground raked and clear, taking away the seeds, during the season will certainly eliminate a lot. But whatever seeds do manage to sprout and any sprouts from roots will still have to be dealt with the old-fashioned way, pull them out. And the sooner you catch them, as you already noted, the easier they are to get out. If they are falling in grass, mowing closely during the seeding season would at least slow them down, but if they are falling in planted beds, even that is out. We wish there were a magic spell we could offer you, because we would be using it ourselves.