Q. I have grown impatiens on the north side of my home in containers for a number of years. Until the last 4 or 5 years they have been great, lush and beautiful. Now for the last few years they have black dots appearing on the leaves and blossoms with the dots eventually turning yellow. The plants are stunted and just seem to be hanging on, never really becoming bountiful and lush as in years past. I have changed the soil every year with commercial potting soils of various types but always this blight comes back. What should I do differently?
A. I am not able to make a specific diagnosis from just that description, but one possibility could be the Impatiens Necrotic Spot Virus (INSV), which is spread by thrips feeding on the plant foliage and flowers. Compare your plants to the following for more information on the disease, http://www.ppdl.purdue.edu/ppdl/weeklypics/3-17-03.html, and the thrips that spread the virus, http://extension.entm.purdue.edu/publications/E-110.pdf.
Since you’ve experienced this ongoing problem for a number of years, it would be helpful to submit plant samples and/or digital photos of your plants to the Purdue Plant and Pest Diagnostic Lab, http://www.ppdl.purdue.edu, so you’ll be in a better position to know what to do next year.
Q. The local garden shops are offering perennials at bargain prices this time of year, but I am moving this winter and so not able to plant them until next spring. Will perennials keep in pots through winter?
A. Different species will vary in their root hardiness, even if otherwise hardy when planted in the ground. I have successfully overwintered daylilies and hosta in pots over the winter, in a fairly protected location on a patio near the house, but otherwise no special handling. On the other hand, I have lost other species treated the same way. It would be safer to create a temporary planting/storage bed in a nursery bed. You could even sink the entire pot in the ground. Another similar strategy is heeling-in: Dig a trench large enough to accommodate the size of the pots, then line the trench with straw or other mulch to make for easier lifting in spring when you’re ready to plant in a permanent location. If that is not possible, and if it’s a great bargain, it might be worth taking the risk of overwintering above ground. Try to keep them in an area that will be protected but not widely fluctuating in temperature. It would be best for them to stay in dormant condition until ready for planting in your new location.
Q. I would like to start a new tart cherry tree from my deceased parents’ tree as a remembrance. Is this possible to do? And if so, how do I do it? I did read that tart cherry trees are fortunately self-pollinators.
A. It is not impossible, but it is a bit of a long shot for most gardeners. Cuttings alone are not likely to produce the same quality, since most home fruit trees are grafted onto a specific type of rootstock. And it may be hard to find small home orchard quantities of rootstock, not to mention that grafting does require some pretty good knowledge, skill and patience! And it will be many years before a newly grafted tree will be fruitful.
You’ll find a pretty extensive list of fruit nurseries in this publication from Penn State Extension, http://agsci.psu.edu/fphg/nursery-fruit; some of these nurseries may sell small quantities of rootstock for home orchardists.
If you know what variety your parents’ tree is, you would be better off purchasing a nursery-grown tree of that kind if fruit harvest is your main goal. But if your main goal is to keep a start of the specific tree, then it can’t hurt to try. Here are some excellent resources on both growing cherries and also specifically on grafting.
Purdue Plant Propagation CD-ROM
Penn State Backyard Fruit Growers