At this time of year, as evenings become a little more chilly, we can keep out the cold by pulling on a sweater or snuggling into a warm jacket as we brave the night air. But remember that plants feel the cold, too, and you can help them bundle up and stay protected against the coming winter weather.

One major problem that can harm your perennials is when the ground freezes then thaws then freezes again… and again. This can happen even in quite temperate regions during an unusually severe winter, and of course in some regions every winter could be called severe!

Plants subjected to repeated freeze-thaw-freeze conditions tend to “heave” their roots out of the soil where they can become frost-damaged. Mulching your plants can help protect them against the effects of freeze and thaw. There are plenty of choices when it comes to mulch, including straw, shredded bark and pine needles. One major benefit of straw is that it is hollow, allowing an effective layer of insulation without being too tightly packed.

Apply a winter “coat” of mulch about 3 to 4 inches deep around each plant. (If the plants are in an area that is unprotected from the elements or open to strong winter winds, you can safely add an extra inch or two of mulch.) Then gently pull the mulch back from the stem or truck with your fingers. This allows the plant to breathe and helps diminish the likelihood of disease problems.

Don’t make the mistake of adding the protective winter mulch too soon!

My best advice is to wait until after the first really freezing cold night, but before you expect any possible snowfall. Why wait? Mulch too early and you could be providing comfortable nesting areas for rodents that might chew on the plants you’re trying to protect.

It isn’t just the roots that can need some protection against the elements. A particularly hard frost can cause “above ground” damage, too. There are various commercially-made plant covers available from catalogs and garden centers. They are made from weather-resistant polyethylene and secure around the bottom with pull-tabs. Available in various sizes, they are fairly easy to slip over the top of the shrub or bush.

If you prefer to get creative, you can use lawn and leaf bags, and I’ve even seen sheets of bubble wrap shaped into plant covers. Plant covers should only be used when you are expecting a severe frost that could damage delicate plants. Remove the covers as soon as the immediate danger has passed. Do not leave plants covered for extended periods.

In the fall and winter, it’s not just cold weather that can attack your plants. Deer, rodents and other wildlife can cause quite a lot of damage, too. In a future column, I’ll discuss how to keep your plants off the all-they-can-eat “critter buffet.”

In a recent column, I included a letter from a reader who had brought some hibiscus seeds from Canada to her home in the US. Another reader, David A. Bequeaith, who saw that column, took me to task for not pointing out the potential problems that can result from bringing flora into the United States from foreign countries.

As a general rule, the USDA warns against importing foreign plants, and in some cases, ignoring these warnings can result in heavy penalties. Over the years, I have worked extensively with the USDA, often addressing issues relating to the import and export of plant materials. Indeed, I should have mentioned the potential problems and inadvisability of bringing in plants from other countries.

So my advice to those who might be thinking of bringing seeds with them from a foreign trip: If you are in any doubt at all about the legality and safety… Don’t do it!

The Plant Man is here to help. Send questions about trees, shrubs and landscaping to steve@landsteward.org. For resources and additional information, or to subscribe to Steve’s free weekly e-mailed newsletter, go to www.landsteward.org

Regular readers of this column will know that I also host a weekly e-mailed newsletter. Today I thought you would like to see some recent questions that were sent to that newsletter, as well as some of the answers that I gave in response.

QUESTION: “It is weird that I am writing you. I came home last night with a bag full of black walnut seeds from my uncle’s farm. My wife handed me your article on proper care for black walnut trees today. My intention is to plant some in my yard, and use the rest for dyeing. Anyway, your article seemed to be concerned with sapling trees, but what about growing them from the seed? Should I just dig a hole and plant, or should pot it for the time being? I live in Columbus, OH, on former farmland, so the soil basically sucks. Lots of stone, and I imagine a lot of clay. Any tips for seedling growing?

“On another note, I have a red oak sapling that is bent from the top being too heavy. The small trunk is sort of an “s” shape. I have it staked with a shepherd’s crook, but I’m afraid that removing it will just destroy it. Again, any thoughts? Thanks for your time.” – Charlie Higley

ANSWER: Your walnuts can be planted in the soil right now. Leave them in the hull and plant to cover about one-inch deep. If you cannot plant them immediately, just be sure they don’t dry out, otherwise you could adversely affect their ability to geminate.

There is a very helpful online guide titled “How to Grow Black Walnuts,” produced by the Kansas State Agricultural College. You can find it at http://www.oznet.ksu.edu/pr_histpubs/Pubs/SC013.PDF and you can click on a direct link when you find this column under The Plant Man heading at my Web site, www.landsteward.org. > From your description, the red oak does sound top heavy. My suggestion is to try pruning some of the branches and out growth to take away some of the weight.

QUESTION: “I had a large hibiscus purchased from a florist that sat in a west facing window. The non-stop blossoms were show-stoppers and I managed to harvest 3 seeds from the plant. When I moved to the US from Canada I could not bring my plants but was thrilled when one of the hibiscus seeds germinated and grew. Now, 10 years later this plant has never bloomed despite my best efforts. I feed, prune and place it outdoors for the summer. What can I do to make this plant bloom?” — Lynda Birmingham AL

ANSWER: “There are ‘blooming things’ that you can purchase from most garden centers and you might want to try one of them. However, there is a trick I use with wisteria around November when they go dormant. I take one tablespoon of Epsom salts and dissolve it into a gallon of water and saturate the soil at the base of the plant. In the spring, I repeat the process just before they start to leaf out.

One other thing comes to mind in that, since you only have the seed from the plant, you might have just a seedling and not the cultivar of the exact plant. If that is the case the bloom will not be the same as the original one with the non-stop blossoms.

QUESTION: “I have a question about an American Elm. I am wondering what would be the spread of this magnificent tree with a height of 100 feet. We live in the city so a tree of that size might be a bit overwhelming. My neighbor’s elm is about 50 feet in height with a spread of about 40 feet.” – Wende

ANSWER: As you’ve noticed, ‘shorter’ elms can have a spread that is about the same width as the height of the tree… up to a point! If the elm continues to grow – and some can reach 100 to 110 feet tall – it will end up with a spread of one half to two thirds of its height. That’s quite a spread!

The Plant Man is here to help. Send questions about trees, shrubs and landscaping to steve@landsteward.org. For resources and additional information, or to subscribe to Steve’s free weekly e-mailed newsletter, go to www.landsteward.org

Today we have questions from several different parts of America… and even one from India!

QUESTION: “I planted some Rosa rugosas and butterfly bushes last spring. All are doing very well. My question is whether I need to prune these back before winter sets in. I live in Albany NY.” — Gay Malin

ANSWER: The butterfly bushes can be pruned back once they go dormant. In fact I recommend cutting them back to about 6 inches for the first year and gradually giving them a bit more each year when pruning. The Rosa rugosas are best pruned in early spring, primarily for shaping and to cut out any dead branches or any that are touching or crossing each other.

QUESTION: “I am looking to create some privacy landscaping. What would you recommend for salt air? I would like a mixture of evergreens, crape myrtle and grasses. Not sure of the best evergreens for the seashore.” – Deborah Lukens

ANSWER: The evergreens you should use will depend largely on the Plant Hardiness Zone in which you live. If you are in zones 5 through 8, I would recommend Cedar Green Giants for the background of your privacy block, with crape myrtles, laurels or Rosa rugosas on the inside for all-summer color. Grasses and colorful perennials are also a good addition and can give a welcome look to a landscape.

As always I suggest that you sketch out a plan to get your ideas down on paper before you start the project. A background line of Green Giants and soft curving lines of color and texture on the inside will help to create a visually pleasing landscape.

QUESTION: “we have a camping site where sometimes snakes appear. Is there a chemical whose smell would keep the snakes and other reptiles away from the tents, or any method by which we can keep away the snakes?” –Rakesh Jain (Indore, India)

ANSWER: The best things we have always used are moth balls. There are products on the market, of course, but virtually all use the same ingredient found in common moth balls.

QUESTION: “I purchased a Japanese Red Maple sapling nine years ago. It had red leaves for several years, but the leaves have been green for the past two years. The tree is now 15 feet tall; beautiful, but green. How can I help the leaves turn red again, or can I?” – Michael Riley

ANSWER: There are several elements to consider here. First, take a look at the area around the tree to see if it has changed over the years. Japanese Red Maples need mostly full sun to stay red, otherwise they will revert back to green. Has anything been built near the tree causing it to be shaded or is another plant growing between it and the sun?

In some cases, using too much nitrogen rich fertilizer can cause the leaves to turn green. If you’ve been using fertilizer around the tree, you could try cutting back or stopping altogether in that vicinity.

QUESTION: “We planted lavender 3 years ago in our garden on the Eastern Shore, Maryland. Nothing happened the first year the plants stayed their original size (about 3″). The second year they started to grow and looked like we had achieved our goal. This year they were flourishing, fragrant and tall.

“Then one day they all just seemed to dry up and die. I’m not sure if they are dead at the root or what happened. It has been hot and dry then wet with high amounts of rain. Should I start over or leave them?” – Janice Enright

ANSWER: The same problem with lavender happened to us too. Lavender is a Mediterranean plant and does not do well with a lot of water. After some trial and error, we have been able to keep ours flourishing by having a sand bed underneath for drainage. We never water, and you should never fertilize. This is the only way we have found to grow it successfully.

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to steve@landsteward.org and for resources and additional information, including archived columns, visit www.landsteward.org

When it comes to fall color, it’s not only trees that put on a dazzling show. Select the right shrubs and you can have a display of autumn colors closer to ground level. Here are a few of my favorites:

Burning Bush (Euonymus alatus compacta)
It is sometimes called Cork Tree or Dwarf Winged Euonymus, but nothing can better describe this shrub than the name Burning Bush! In the fall, the foliage turns to such a brilliant – almost luminous – red that it almost seems too perfect to be real. But real it is, of course.

If left untrimmed, it can reach a height of about 6 to 10 feet and produces orange/red berries that provide food for wildlife through the winter. A row of Burning Bushes in front of your house, particularly if backed by a white or light-colored wall, will create a colorful welcome to visitors in the fall. Although Burning Bush is somewhat shade-tolerant, you’ll see the brightest color if the shrubs are planted in full sun.

Fothergilla (Fothergilla Hamamelidaceae)
Like many plants, this one has an interesting history. It is named after Dr. John Fothergill (1735 – 1780), a physician and botanist, who championed the cause of the American colonists and became a friend of Benjamin Franklin.

Fothergilla is a dense, compact shrub producing fragrant, feathery, white flowers in the spring that remind me of bottle brushes. The rounded, dark-green leaves turn to a delightful orange-red and even scarlet. Fothergilla are tolerant of most soils, but do best in acid, moist, well-drained soil.

Clethra Ruby Spice (Clethra alnifolia Ruby Spice)
The first time I saw this plant (or to be more accurate, a whole section of them) growing at a friend’s nursery, I was immediately struck by the cinnamon-like fragrance that was apparent from at least 50 feet away! It was July and the clusters of pink flowers were in full bloom.

Later, in the fall, the foliage becomes a very pleasant shade of yellow and then golden-brown. Ruby Spice is a good choice for shrub borders or around water features. I don’t recommend planting in drought-prone areas, but on the other hand, it is fairly adaptable to semi-waterlogged clay soils.

Little Henry (Itea virginica)
Little Henry could be a good choice when you’re looking for an attractive perennial shrub that maintains a compact size. Topping out between 1 and 3 feet at maturity, Little Henry is a semi-evergreen with dark green leaves that turn to a reddish tint in early fall and then go all the way to remarkable shades of dark crimson and scarlet as the temperatures drop. As I have said before, Little Henry is the one plant that can truly rival Burning Bush when it comes to eye-popping fall color.

I’ve found Little Henry to be quite easy to grow and it seems relatively free of problems associated with disease and insects. It’s an adaptable little fellow, tolerant of damp or dry soils, variances in pH and tolerant of light conditions from shade to full sun. I’d say Little Henry would be a good choice to cover a bank or a hillside that’s not easy to mow. It looks good around a pond or lake, too.

Shenandoah grass (Panicum virgatum)
This elegant ornamental grass is sometimes mistaken for Japanese Blood grass, but is just different enough to give your landscape a unique edge. Shenandoah has a cascading form with foliage that starts out green with the tips beginning to turn red by about mid-July. By the fall, the entire plant will have turned to a mixture of orange and red, for a spectacular display.

Shenandoah is a fairly fast-growing grass that can reach a height of around 4 to 5 feet. Plant it where it can get the benefit of full sun in order to achieve the full benefit of the spectacular color.

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to steve@landsteward.org and for resources and additional information, including archived columns, visit www.landsteward.org