Franklinia and Wisteria Questions

Two separate questions:
1. I live in Raleigh, NC and have a Franklin tree that could use some help. It's now about 3 years old, is planted in an area that includes pines and rhodos. I've seen one that has been kept in a pot and the leaves are beautiful--not like mine.
Could you advise me re: the correct soil ph as well as what the best fertilizer would be. Also, I'll be moving next year--is there a more optimal planting situation than it's present one (it's coming with me).

2. I have a beautiful Wisteria growing along the top of a large Pergola. The problem is that suckers keep breaking through the dirt in my planting bed and are not confined to the trunk area but break out all along the root system. I simply cut them off, but there are so many--is there any way to combat this or stop it altogether without killing the plant?

Answers:
Let’s begin by talking about the Franklin tree, Franklinia alatamaha.

Franklin trees grow best in a moist soil with a fair amount of organic matter. They are also known to have a rather sparsely fibrous root system (according to Dirr’s Manual of Woody Landscape Pants). Given those two factors, I would think that even three years later you want to still be supplying the tree with a fair amount of supplemental irrigation. Do you have a soaker hose or drip irrigation system set up? I would think the tree’s root system should still be saturated two or three times a week for 2-3 hours each time. Hopefully you amended the soil with a fair amount of compost when you planted the tree. If not, I would top dress the area right around the base of the tree with an inch or two of fresh, rich compost. If you have mulched under the tree already then you might want to remove some of the mulch and replace it with, or at least mix in, the compost. Avoid mounding compost or mulch right up against the trunk of the tree. Spreading out a few feet in diameter, your tree pit only needs a couple inches of compost and/or a compost and mulch mix to provide enough insulation for the summer months while providing nutrients to the building root system. If I were you I would not fertilize your tree with anything else at this time, especially if you are going to move it again soon. In fact, I am rarely a fan of fertilizing trees as they will prefer to grow and produce stem and foliage tissue by their own schedule, not ours. Going back to the sparse root system Franklin trees can have, consider hiring some skilled landscapers who are really good at balling and burlapping trees for the transplanting effort. If you really want to save the tree it is going to be worth the extra investment. If the root ball gets really jarred or beaten up during the move you might be dealing with that stress for years. When it gets moved, I would recommend a product called PHC Tree Saver to be incorporated into the hole (amended with compost) once the tree is in place. Here is a link to PHC’s website, and hopefully you can find a retailer near you that carries it: http://www.planthealthcare.com/HT/Mycorrhizal/PHCTreeSaver

The tree can tolerate some shade but you will get the best flower and most glossy leaves if it is in a full sun application. Definitely set up supplemental irrigation in its new home for a year or two to make sure it takes to the new situation. Rely on compost and mulch to provide a steady slow release of nutrients to the root system. A few references speak to soil pH but they do not always agree with each other. A member of the camellia family, Theaceae, I would guess they would like a soil that is slightly acidic to neutral (6.0-7.0). One reference says that they can tolerate slightly alkaline soil, but I have never seen one in that kind of situation. Since wild populations of these trees have not been found in over 200 years it seems to me that there is a fair amount of guessing in this regard. The best specimens are found in slightly colder climates (Massachusetts, Pennsylvania, etc.) but obviously your tree can be grown down in the Carolinas as shown by your friend.

Then there is the wisteria:

Suckers and water sprouts are what we horticulturists call kinds of epicormic growth. The catch with pruning them back this time of year is that the plant is growing most actively and continuing to produce plant growth regulators (what people tend to call “plant hormones”) that will continue to push out new growth from dormant buds right below where you are cutting. The only trick I have learned is to prune those unwanted shoots back in the fall as the plant is beginning to go dormant. In the fall your wisteria is going to produce another plant growth regulator that will aid the plant in going dormant for the winter. By pruning at this time you will (hopefully) trick the plant to not want to produce new growth from those points. Or, if they do, the hope is that the growth is so young and vulnerable going into winter that they do not survive and eventually die-back. You will have to repeat the process for a few years as wisteria are so aggressive (invasive!?!), but hopefully you can get the situation under control.

Manhattan Terrace Vines

Question:
I'm a first-time gardener. I need an advice on perennial (flowering) vines for the terrace. Privacy is a priority, but beauty and fragrance are almost as important. I love morning glory but was told it's annual. Any advice will be much appreciated.
Also, what's the prevailing opinion for the jasmine on the terrace?

Answer:
Let me ask you a few questions so that I can best help you.
What direction does your terrace face and how is the sunlight throughout the day? Do you have strong winds or salt spray exposure?

To begin, morning glories are annuals, and even though they can fill in a small fence or railing quickly in one season they are not expected to come back. As far as jasmines, they too are mostly annuals, at least the climbing species that you are most likely referring to. I once wrote a quick document of some of the most popular vines here in the city, and they are the following:

Clematis sp. - clematis - climbing vine to 10’
Sun to part shade; moist organic soil; vine does best with sunny stems and protected, cool roots; known for vast color variation to cultivars; Clematis montana grows tall with small white flowers mid-summer; Clematis x jackmanii popular for large violet flowers; Clematis tangutica has yellow flowers and fluffy seed heads; plant clematis on a North, East or West exposure on a narrow-spaced trellis system

Hydrangea anomala var. petiolaris - climbing hydrangea - climbing vine to 50’
Full sun to part shade; dry soil; good on north or east exposure; wind and salt spray tolerant; white flower clusters mid-summer; woody cinnamon bark when mature; grows by aerial roots, best planted up cable system off separate from building exterior

Lonicera sempervirens - scarlet honeysuckle - twining vine to 12’
Sun to part shade; moist organic soil; plant on a South, East, or West exposure; must be trained at first then climbs well on its own; scarlet flowers followed by small red berries; gray-green leaves; exfoliating bark at maturity; North American native

Akebia quinata - chocolate vine - climbing vine to 30’
Sun to shade; dry organic soil; spicy vanilla scented pinkish-purple flowers in spring; nice rounded leaf is palmately compound;

Parthenocissus quinquefolia - Virginia creeper - climbing vine to 50’+
Part shade to shade; moist soil; excellent red fall color; very aggressive grower, requires maintenance; grows by adhesive sucker, train up trellis system; North, South, or East exposure

Parthenocissus tricuspidata - Boston ivy - spreading vine to 70’
Part shade; moist organic soil; glossy foliage; good fall color when planted in some sun; very aggressive grower, best trained up a trellis system; will perform well on a North, South, or East exposure

Schizophragma hydrangeoides - Japanese hydrangea vine - climbing vine to 40’
Sun to part shade; dry organic soil; fragrant midsummer flowers

Pyracantha sp. - firethorn - woody vine to 15’
Tolerant of most soils and exposures; clusters of white summer flowers followed by fruit-set in fall; P. atalantioides has red fruit; P. coccinea has orange fruit

Lastly there is Campsis radicans, or trumpet creeper, and I discussed that in a blog spot from last summer that you can revisit here.

Please note that vines such as Virginia creeper and Boston ivy I listed as aggressive growers which need to be trained up some sort of system that stands off of the building exterior. These vines have such adhesive suckers that they really should not be planted right up against a building because they will cause serious damage to the façade over extended periods of time.
Also, you should be aware of the HSNY Library here on West 37th Street. Open to the public and well over 10,000 volumes we have plenty of information to share with you when you feel like educating yourself further. You can find more information about the HSNY Library by clicking here.

Plant ID: Mandevilla x amoena

Question:

My friend was given this plant but is unsure of what it is called.
Can you please tell me what it is and how to overwinter it here in Michigan?

Answer:

The plant your friend was given is called a mandevilla (Mandevilla x amoena). Native to Brazil, this climbing vine is a hybridized cross of Mandevilla amabilis and Mendevilla spendens. Because of its tropical origin, the plant cannot tolerate winter temperatures below 55 or 60 degrees. Therefore, the only option to successfully overwinter the plant in Michigan is to bring it inside. Keep it in an area of bright light, but be careful that it is not too close to a hot, dry radiator. Continue to water it as you have been, and as winter comes you can ease up and water more sparingly. When overwintering tropicals inside, I like to use below the pot a glazed saucer with a layer of stones or pebbles in it. This way excess water that is in the saucer can evaporate and provide a little extra humidity during the dry winter months without running the risk of rotting the roots of the plant. You can also mist the foliage if you feel the plant is getting too dry. A reference book I have says to cut the plant back to keep it bushy and promote next years flower, but I might recommend against that. I had one in my home years ago that I cut back hard this time of year and it seemed like forever before it got to be as full as it was. I prefer to stake it well and let it continue to climb. Through the winter the vine should continue to grow and put out new foliage, but do not expect much in the way of flowers until next summer. When you move it outside next spring check on the roots as it may be ready to be repotted.

Reference: Indoor Plants: The Essential Guide to Choosing and Caring for Houseplants by Jane Courtier and Graham Clarke, Reader's Digest, 1997.