Impatiens still vulnerable to disease

Impatiens will likely be plagued by downy mildew

Impatiens will likely be plagued by downy mildew for at least a few years. (2/24/01) (Credit: Newsday/Julia Gaines)

Gardeners across Long Island are still mourning the loss of impatiens. Having fallen victim to downy mildew during the summer of 2012, the favorite summer annuals are expected to be vulnerable to the disease for years to come.

Most local nurseries did not sell impatiens this year, as doing so would have been irresponsible. And although some gardeners refused to heed the warnings, sought out the beleaguered plants and planted them anyway, they were likely to find their time and money was wasted; by late summer there were holes in gardens left behind by plants that simply could not make it.

Over the summer, however, I also heard from a few impatiens-loving readers who were holding on to hope:

PHOTOS: Plants that promote a healthy garden | Invasive plants and alternatives

MORE: May gardening chores | Garden Detective blog | Gardening 101

I was cleaning up my garden and discovered a beautiful rare impatiens that must have survived the blight of last summer. -- Kathy Mosinka, Valley Stream

I have found impatiens that I assume self-seeded from last year in my garden. They look healthy. I was wondering if I could pot them and replant them next year. Is that possible, and where do I keep them and care for them until next year? -- Maryann Battista, Plainview

Why are these plants alive and doing well this summer when we were told that the downy mildew would get them as it did last year? -- Ronald Johnson, Stewart Manor

The strain of downy mildew that has been destroying Impatiens walleriana in the region can survive winter (possibly many winters) in the soil, so planting healthy impatiens in gardens where infected plants grew previously would likely doom them. The disease also is airborne, so if impatiens are planted in other parts of the garden in healthy soil, they can be infected by spores anyway. Even so, sometimes -- either because plants are growing in a protected area or spores just don't blow in their direction -- impatiens and their owners can get lucky, as these three readers have.

However, I would not recommend trusting your garden to luck. Impatiens have a better chance of contracting the disease than not, and spending money on plants or trying to keep a healthy plant alive and well indoors over the winter (by your sunniest window, by the way) might not be worth the cost or effort.

DEAR JESSICA: A squirrel must have planted a pine cone in the front of our garden, because a lovely pine tree is now about 3 feet tall and 2 feet wide. I would like to know the best way and time to replant it so it will live. How deep and how wide should we dig to ensure it won't die? What else will it need after it's moved? -- Janet Chall, Great Neck

DEAR JANET: Most pine cones do not release their seeds unless exposed to temperatures of 130 degrees or higher. That's nature's way of ensuring: 1. The Earth doesn't turn into a forest, and 2. Trees are replaced in the event of fire. Still, sometimes seeds are released and sometimes squirrels do move things around. No matter how it got there, the result is you have a lovely "volunteer" tree that you'd like to keep.

Evergreens are best relocated in September or October for a few reasons: The cooler temperatures and more regular rains that typically come with fall mean you won't likely have to fight heat and drought to keep a newly planted tree from becoming overstressed. And although air temperatures begin to drop, the soil temperature is still warm enough to allow roots to grow for six to eight weeks and become established enough to make it through winter. Plus, trees planted in autumn will have a head start over those planted in March, which is the second-best time to plant and transplant.

It's best to relocate all plants on a cloudy day. Prepare a planting hole that's wider than the existing root ball and about as deep. You'll have to estimate the depth and adjust it after you dig up the tree.

To remove the tree from its current location, dig a circle around the tree that's one foot in diameter for every two feet of tree height. For a 3-foot tree, you should dig a hole that's 1.5 feet wide. Don't skimp on this, as the vital-yet-smaller delicate feeder roots are the farthest away from the trunk, and severing them may result in transplant shock. Replant the tree, taking care to maintain its original soil depth, tamping the soil as you go. Water well immediately and regularly for the first two growing seasons, including during winter if there is no snow cover and it hasn't rained in a while. Mulching will help retain soil moisture.

DEAR JESSICA: Our arborvitae are growing numerous yellow beads. Two years ago I had them trimmed on top. Can you please explain this sudden change, and will it keep occurring? -- Frank Muhlbach, Hampton Bays

DEAR FRANK: Arborvitae means "tree of life," and those yellow "beads" actually are fruiting bodies, or cones, that contain seeds. You don't say how old the trees are, but the cones are just a sign that they have reached maturity and are not a cause for concern.