Archive for the Ask MG department

What is a good flowering shrub for a fence line?

March 7, 2023 • Leave a Comment

I am looking for a flowering shrub to go along a 6-foot high white fence. I would like it to grow to 3 feet wide and 2 to 3 feet tall.

There are several possibilities that can be maintained to size with relative ease. Planting in front of a white fence reflects heat on the plant. That heat can accelerate flower production but also dry out the soil sooner. Flowering shrubs need a minimum of 6 hours of sunlight each day and consistent watering. Use mulch to minimize water loss. The soil should be loamy and enriched with compost.

Flowering shrub - Dwarf Korean Lilac (Syringa meyeri 'Palibin') Photo: Bailey Nurseries — **Dwarf Korean Lilac (Syringa meyeri ‘Palibin’) Photo: Bailey Nurseries**

Dwarf Korean lilacs (Syringa meyeri ‘Palibin’) bloom mid to late spring with highly fragrant pink flowers. Shear after bloom to maintain the 3- by 3-foot dimension. The dark green glossy foliage provides a nice contrast to the white fence and can behave as a deciduous hedge. If you want a little height, arrowwood viburnums (Viburnum dentatum) have strong upright growth and flat white flowers in spring. Blue Muffin (‘Christom’) grows 3 to 5 feet tall, with blue-black berries that persist if not eaten by birds, and shows orange to burgundy red foliage in fall. Like the lilacs, hand pruning and thinning after bloom will keep the height at the desired level every other year.

Examine the wonderful single and double Knock Out roses. Introduced in 2000, they have become a mainstay in the summer garden, producing flowers continuously from spring until hard frost. Extremely hardy and disease-resistant, they live up to their name.

ELSEWHERE: Viburnum dentatum

What caused holly berries to not appear in the fall?

February 18, 2023 • Leave a Comment

For years, our holly bushes have been lush with fall holly berries, but not last fall. I think they got their fair share of water during the summer heat wave. Any thoughts?

Think back to April 2012 and what happened with the late frost and freezing temperatures at the end of the month. Many of our beloved spring-flowering trees were heavily damaged at a critical time in fruit formation. The holly bushes were no exception. Even though the buds form in the fall of the previous year, April would have been the time these tiny flowers in the leaf base on male plants would have been opening. Many flowering shrubs and trees suffered great damage last spring due to the sudden cold temperatures. Michigan’s cherry and apple industries were significantly impacted by the cold snap.

Although the holly plant is basically a male plant, their flowers and subsequent pollen are necessary for the fertilization of the flowers on the female berry-producing plants. If they aren’t there, the female flowers are not pollinated and there is no berry. Maintaining a consistent watering routine early in the summer as well as during drought periods will also prevent premature berry drop. Covering plants when a freeze is posssible can substantially decrease the loss of flowers and future berry production.

Elsewhere: Winterberry: Michigan’s native holly

Why do cracks on tomatoes occur while still on the vine?

February 3, 2023 •

Resistant varieties come in all sizes and types. ‘Mountain Spring’ (a large red), ‘Sweet Million’ (a small-fruit variety), and ‘Mountain Gold’ (a yellow tomato) are just three selections that are not so prone to cracking.

Cracks on tomatoes that circle the stem end or stretch down from the stem end can be very annoying. They not only deform the beauty of the fruit, but also leave it susceptible to rot. The cause of cracks on tomatoes is generally a growth spurt caused by a prolonged drought. The solution is to provide your garden with adequate and consistent water. You need to water to keep the soil evenly moist. In Michigan, we can have full weeks of rain followed by a month of nothing.

If droughts are common in your immediate location, then besides monitoring the watering, try to look for and select a crack-resistant variety next season. Resistant varieties come in all sizes and types. ‘Mountain Spring’ (a large red), ‘Sweet Million’ (a small-fruit variety), and ‘Mountain Gold’ (a yellow tomato) are just three selections that are not so prone to cracking.

Answers compiled by Martha Ferguson, and contributed by Beverly Moss, Michelle Dunham and Chuck Tyrrell.

ELSEWHERE: Tomatoes exhibiting cracks this summer

Choosing the right location and container for SunPatiens

January 18, 2023 • Leave a Comment

In my back yard, I planted SunPatiens in a container that gets sun in the morning and afternoon and some in the evening. These plants thrived, with little fertilizer and just periodic watering. On the other hand, the SunPatiens that I planted in the front (facing west) wilted and lost their leaves rapidly. I watered them daily, sometimes twice. I removed them from their pots and found root rot. So I bought some fresh plants, drilled more drainage holes, but the same thing happened. Any ideas on what the problem is?

Your descriptions of the health of the same plants in the two different locations seems to tell the story. Typically, container placement is different in the front of the house as opposed to the back. More than likely your backyard containers are away from the house walls and windows, perhaps out on a patio or deck where they can be seen from the house, but not against the house, maybe even out in the lawn or near garden beds. The containers in the front are probably nearer to walls and windows to be seen and enjoyed on the approach to the front door. Buildings absorb, reflect, and intensify heat. To make matters much worse, new windows with low-E glass or older windows that have been coated with a UV ray coating really intensify the heat that is reflected. The plants are being heated to an extreme. You water more, causing the root rot, but the death rays of heat continue to zap the foliage. Increasing the number of drainage holes in those containers is helpful to prevent root rot, but still you must water more and more as the reflected heat continues to hit the plants. The only real prevention is to move the containers a safe distance away from walls and windows. Easier said than done probably. Another complication to consider is the size and shape of the pots. The large container in the back will hold more moisture longer, a smaller container dries much faster, such being the case with the original hanging containers. The wider and lower a container is, the slower the water drains away. The taller and narrower the container is, the faster it drains, even if the two containers are filled with the same amount of potting mix.

Answers compiled by Martha Ferguson and contributed by Beverly Moss, Michele Dunham, and Martha Ferguson.

Are wood ashes and sawdust good for compost and the garden?

October 26, 2022 • Leave a Comment

**Compost is a great way to feed plants with organic waste from the kitchen and garden.**

Can I apply wood ashes from my fireplace to my garden beds? If not, is it OK to add to the compost pile? What about sawdust from the workshop?

Applying wood ashes that are free from contamination should be OK if it is done when the garden is not planted and filled with growing plants. Spread a uniform, thin layer of ashes (a covering about the thickness of a sheet of paper) over the garden. This can be done in conjunction with the incorporation of other organic material such as manure or compost. In either case, the ground should then be tilled thoroughly to an 8- to 12-inch depth. It is also OK to add these uncontaminated ashes to your compost pile in moderation.

Sawdust is a good component for a compost pile. Mix sawdust with dense materials such as grass clippings, wet leaves, vegetable remains, etc. This will allow air into the mix. More air speeds up the composting process and cuts down on potential odors. Do not use sawdust created from cutting treated lumber.

Also from Michigan Gardener: Putting flowers in compost pile

Elsewhere: Wood Ash in the Garden

How do I care for transplanted roses in spring?

March 31, 2022 • Leave a Comment

Last October, I transplanted two climbing roses and a standard rose bush. What should I be doing for them this spring?

There are four basic tasks for transplanted roses. First, carefully remove winter protection about the time you see crocus and tulips emerging from the ground. That indicates the ground temperature is warming slowly and your roses will be taking up moisture soon. If any of your roses were grafted, expose the graft union and check for growth buds on the rootstock (below the graft). You do not want to encourage these rootstock sprouts—remove them. On your climbers, if you have laid the canes down on the soil and covered them up, now is the time to uncover and gently lift the canes up and attach them again to their support structure.
The second task is pruning in April, when you start to see bud swell on the canes and branches, or around the time forsythias bloom. Remove dead branches and prune for air circulation, crossing branches and aesthetic cane length based on the supports.
The third step is their first feeding, which can be done at pruning time. A general slow-release fertilizer blended for roses is great. Spread it at the dripline and gently scratch it into the soil. Roses are heavy feeders. Many rose growers use organic supplements, such as fish emulsion or additional slow-release granular fertilizer, once a month until August to keep them healthy against disease and insect attack.
Lastly, as the roses start to push out leaves and new growth, apply a preventative spray for fungal diseases like black spot. A horticultural oil spray later in May into June can help with insect problems.

What are good plants to give as a wedding party favor?

March 14, 2022 • Leave a Comment

At our upcoming wedding, we want to give a seedling or plant as a wedding party favor. We need suggestions as to what tree or plants can be planted in Michigan in September. Since there will be about 500 guests, the price of each plant must be relatively low.

Congratulations on using a plant as a wedding party favor! One of the best choices for fall planting, and a Michigan native, would be a white spruce (Picea glauca) seedling. These strong conifers transplant easily, and tolerate a wide variety of soil types and sun conditions. They are used for windbreaks, lumber, and sometimes Christmas trees. They have a strong conical form and hold their limbs out horizontally. The dense branching provides shelter and food for birds and other wildlife. What a fitting long-term remembrance of your wedding.

Understanding the large quantity, you want to deal with a local wholesaler/retailer that can offer a practical price. Consider Cold Stream Farm in northwest Michigan (www.coldstreamfarm.net). Please remember that 500 seedlings will likely be prepared in bulk. You will have to separate them and individually wrap their roots in a moisture-retaining mulch and secure in a waterproof sleeve. Therefore, timing your order is important so that the seedlings are not stored indefinitely. Once received, you have approximately one week to separate, rewrap and distribute. Prepare a tag for each tree that tells guests to plant as soon as possible and the optimum soil and light conditions.

Scientists estimate there are about 9,200 undiscovered tree species

March 1, 2022 • Leave a Comment

**Coniferous mixed forest, Val Saisera, Italian Julian Alps, Italy. (Photo: Dario Di Gallo, Regional Forest Service of Friuli Venezia Giulia, Italy)**

University of Michigan: A new study involving more than 100 scientists from across the globe and the largest forest database yet assembled estimates that there are about 73,000 tree species on Earth, including about 9,200 species yet to be discovered.

The global estimate is about 14% higher than the current number of known tree species. Most of the undiscovered species are likely to be rare, with very low populations and limited spatial distribution, the study shows.

That makes the undiscovered species especially vulnerable to human-caused disruptions such as deforestation and climate change, according to the study authors, who say the new findings will help prioritize forest conservation efforts.

“These results highlight the vulnerability of global forest biodiversity to anthropogenic changes, particularly land use and climate, because the survival of rare taxa is disproportionately threatened by these pressures,” said University of Michigan forest ecologist Peter Reich, one of two senior authors of a paper scheduled for publication Jan. 31 in Proceedings of the National Academy of Sciences.

“By establishing a quantitative benchmark, this study could contribute to tree and forest conservation efforts and the future discovery of new trees and associated species in certain parts of the world,” said Reich, director of the Institute for Global Change Biology at U-M’s School for Environment and Sustainability.

For the study, the researchers combined tree abundance and occurrence data from two global datasets—one from the Global Forest Biodiversity Initiative and the other from TREECHANGE—that use ground-sourced forest-plot data. The combined databases yielded a total of 64,100 documented tree species worldwide, a total similar to a previous study that found about 60,000 tree species on the planet.

Read more from U-M…

How and when do I train and prune thornless blackberries?

February 19, 2022 • Leave a Comment

How do I trellis thornless blackberries? I have several 2- to 3-foot-tall plants that have many hard-to-tame shoots pointing in every direction. I planted them last spring and none had fruit last year. I wound the longest ones around the wire between the metal fence stakes, which are about 3 feet high. How and when do I prune?

Thornless blackberry primo canes tend to grow along the ground like a vine for the first two years after planting. They also do not produce a large crop the first season. Proper pruning and strong wire support are needed. For thornless blackberries, you need two wires at heights of 3 feet and 5 feet from the ground between posts 20 feet apart. Because of the vine-like nature of this bramble fruit, individual plants should be 10 feet apart.

Now for pruning. Cut back the main trailing canes at the top by several inches in late winter to 4 to 6 feet. That would be roughly March, before bud swell. This pruning forces development of sturdier, more fruitful canes. Keep them tied to the upper wire. For wild lateral shoots, select only those parallel to the wires, trimming them back to about 12 inches. Guide and tie them to the lower wire. Remove cane shoots that go out perpendicular from the wire trellis. This forces the plant to concentrate its energy on the remaining canes for healthy growth and better fruit production. Make sure you prune out any damaged or weak, spindly canes. Proper pruning and trellising will bring your thornless blackberries to an enjoyable production level.

Can I grow ivy groundcover under trees?

February 16, 2022 • 1 Comment

We have a beautiful 32-year-old maple tree in our backyard and a city locust tree on the boulevard in the front yard. It is difficult to grow grass under both trees. If we planted ivy as a groundcover, would it hurt the trees if it climbed up them? My neighbor had some voracious vine grow up his mountain ash and the tree died.

The age of your maple tree suggests a large trunk and root flare with heavy shade. Turf grass needs sun and water, both of which the maple tree takes first with its mature canopy and characteristic surface root system. Give up on growing grass under it. Apply two inches of composted mulch between the root flares out to the canopy drip line. Keep the compost and mulch away from the trunk and off the root flares. You can then “pocket plant” shade-tolerant perennials like hosta and liriope, which will grow comfortably in those conditions, offer seasonal bloom, and give you an interesting, low maintenance groundcover.

One can grow grass under a locust although they too are shallow-rooted. If you thin out the canopy to allow more sunlight to reach the ground, a shade turf seed mix can work if the area is properly prepared. However, a boulevard takes heavy abuse from vehicles and weather. You may be better off applying the mulch method to the locust as well. The liriope is both sun- and shade-tolerant and will handle some road salt applied in winter. There are also creeping junipers that hug the ground and give you conifer presence all year. The key is to plant away from the tree trunk.

Any kind of climbing ivy is difficult to control. Their accelerated rise within a tree’s canopy crowds out the tree leaves. The tree loses its food production source that feeds its roots, which in turn feed the branch scaffold. The tree literally starves and dies, as witnessed in your neighbor’s yard.

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