Wisteria

Q. I have a wisteria growing up the side of my house here in Copenhagen, Gary, which is 5 years old! It is enormous and during the winter period I cut it right back to around 2 meters in height. It is just starting to move into the leafy stage and my question to you is HOW DO I GET IT TO FLOWER! They are such wonderful blue flowers but ours hasn't flowered at all yet.

A. That is the worst aspect of growing a wisteria...not having those lovely fragrant flowers! I want you to test the soil pH. Get a kit from a garden center or call your local agricultural department for testing. It could be that the pH is too high for the wisteria and that is keeping them from blooming. The fact that the vine's energy is going into lots of foliage is a sign.

Another method is to give the vine a highly acidic fertilizer. Here in the States we have one called MirAcid. Look for one that is recommended for lowering the pH and may mention 'for use on rhodies, azaleas, camellias and gardenias', other plants which thrive on slightly acidic soil.

If the pH is above neutral [7.0], then it will keep the plant from flowering and reproducing. It is not happy with the location's soil, therefore will not flower and produce seed. Plants know not to reproduce in environments which are detrimental to their own kind.

Mulch around the vine and till down carefully a couple inches with peat moss or a decomposed sterilized leaf mold. The organic material will aid in producing flowers, too. Best of luck and Happy Cooking, my friend! [Share one of your recipes with us when you have time.

Q. I just read your advice about successfully growing a wisteria and getting it to bloom. I am worried about their roots. Won't they eventually cause a huge amount of problems? I have one growing in a large pot and am afraid to plant it in the ground for fear of the damage the roots may cause as they grow and wrap around everything.

A. Wisteria can get down into sewer pipes, if that is what you are referring to. The roots are thin and fibrous and may penetrate hairline cracks. They run deep and far. If you have underground pipes near where you want the plant to grow, you may be concerned, but it would take years for the wisteria roots to do any damage. Willow trees are notorious for this, far more than wisteria bushes. Other areas of gardens can be far from pipes, so let the wisterias be free to grow and bloom there.

Otherwise, keep it in its pot to protect your pipes if you are worried. But, remember to pot up in size as it enlarges, giving it fresh potting soil with organic material.

Q. I have a Wisteria vine. This is the second year but it is about a 7 or 8 year old Texas graft, Chinese wisteria. Earlier this year it bloomed and had the biggest flowers of any I seen in town. Now it is growing like crazy and I see it is going to bloom a little again so I gave it a high dose of phosphorus and drove in some fruit tree stakes. Is it common for one to bloom twice in the same year? It also has what look to be seed pods hanging from the branches...could it be? If so, can they be grown indoors from those seeds? If so, please tell me how.

A. You are quite an accomplished gardener. It is always a pleasure to hear from someone who knows what they are doing and doing it very well!

Yes, wisteria will bloom a second, though weaker, time, if the vines are happy and yours sure is. The high P is great for the bloom burst. Cut it off as the buds open and switch back to a high N for the rest of the summer, to promote vegetative growth. Your graft is doing fine, and thus shows good age and a good stock had been used.

The seeds form in pods, rather like peas. They will darken to a brown and can be harvested. You can save them in an envelope in a cool, dry, dark spot until late winter and then sow them for spring planting.

The seeds have quite a hard shell, so you should soak them for 24 hours before sowing next year. This will soften the shell and allow water to penetrate into the germ cell and sprout anew. For stubborn ones, you may have to nick the edge to open the shell for water.

Plant them in a moist mixture of vermiculite and perlite in good AM sun. They will sprout in about 2 weeks. Do not overwater, or you may suffer damping off [a fungus which kills seedlings at the soil line]. When 2-4" tall, transplant each into a pot. Peat pots work great, as when they are ready for outdoors, you break them apart a bit and plant right into the garden area!

Q. We moved into a home that has a wisteria vine that was distressed. The vine grew but didn't bloom. The vine, we understand, needs to be trimmed back. When and how far back to the ground level should I trim?

A. Wisteria is a very vigorous, deciduous vine that needs attention during the summer and also in the midwinter dormant season, says University of California master gardener Jan Wiesenfeld. Careful spur pruning at these times will encourage flowering and will help avoid a tangled, overgrown vine. These woody vines can take up to seven years to produce blossoms, so be patient. Wisteria can be a shrub, a tree or an espalier, which is probably the best for displaying the lovely blossoms. Every winter, cut back and thin out side shoots. On the side shoots are the flower-bearing laterals. Cut these back to two or three buds. In summer, a couple of months after flowering, cut back any long tendrils you don't want. You can tie back the stems you want to heighten the vine. Wisteria vines can become heavy, so tie these to a strong support system. Fertilize in early summer with 0-10-10 fertilizer or other low-or no-nitrogen food. Too much nitrogen encourages growth at the expense of blossoms.

From: The Garden Detective

Mark writes~
About 3 weeks ago, I planted two Pink Japanese Wisteria in my flower beds. Since then, the leaves have started turning yellowish, and don't look healthy. They are planted in full sun. What I might be doing wrong?

A. Your plants provide a spectacular show of 18-inch fragrant rose-pink flower clusters hanging from a vigorous, climbing woody vine. Train on arbor, trellis or fence for best effect. An excellent patio cover. Deciduous. Full to partial sun. Fast grower, stems to 20 to 25 feet long.

I suspect a lack of organic material in the soil and/or an improper pH. Please take a soil sample to your local Ag Department for checking or buy a soil testing analyzer from a local nursery.

Wisteria require a location that receives full sun with well-draining soil. To help improve the drainage of the soil once a location has been chosen, "Growing Wisteria" suggests cultivating the soil to a depth of about 24 inches and mixing in compost, peat, or well-cured manure. This should be done at a rate of one part organic material per every three parts of soil. Any rocks, sticks, or debris should be removed from the area before planting.

"Burpee: Complete Gardener" makes the following recommendations concerning the pH level of the soil before planting wisteria. It says it should range between 6,0 and 7.0. There are test kits available in many garden supply stores and most cooperative extension offices. These are very accurate and quite easy to use. When the pH levels are found to be too low, lime may be added according to package directions. If the soil test shows the ground to be too acidic, natural materials such as pine bark, pine needles, and additional peat and manure will help to lower the acid content. The continual use of pine mulch will help keep pH levels in check.

I like this summary I came across:

Wisteria vines are beautiful indeed, but they are not for those wanting a maintenance-free plant. These plants are so hardy they often outlive their caretaker. Wisteria require yearly care and control, but when planted in a good location with a sturdy support, a wisteria vine can be a lovely addition to the landscape. There is no other flowering vine quite like the wisteria.

Written by Kimberly Osburn [wisteriawister]

Q. When do the leaves of a wisteria come out? Before the buds? When do the buds come out? What do the leaves and buds look like? Do you prune a wisteria and if so, when?

A. First, the flowers come out, depending upon the zone where the plant is growing, mid spring, when the days lengthen and the temps rise.

Then, as the flowers reach their peak, the tiny pale green leaves appear, mixed in with the flowers. It is quite attractive, though mostly you see the flowers. As they drop, the leaves get more light and through photosynthesis, they turn darker green and enlarge.

They will grow well all summer long, with the proper care, mainly a good supply of water and fertilizer and at least 1/2 day sunlight. They do not bloom well in total shade, or in climates where the temps do not rise very high. The South US is a popular spot for them, but here we have tons of them which are spectacular each year!

For a good picture of what the wisteria looks like, go to:

http://www.thelaurelsnursery.co.uk/wisteria_range.asp

The Garden Seeker:

Wisterias should be pruned twice each year a/ to ensure plenty of flower bud, and b/ to keep this vigorous climber under control.

Autumn Pruning involves cutting all of the current side-shoot growths back to within 10-12" of the main lateral. This should leave 4-6 leaves on each side-shoot. Obviously, any side shoot required to extend or train the framework should be left and trained as required.

Winter Pruning January/February, cut these side shoots back even further - 3-4" long, leaving only 2 or 3 buds on the side-shoot. These will be the flowering spurs.

Both of these operations should be carried out each year. The only shoots to be left 'unscathed' are those which are required to extend the size or direction of the plant.

The Good Sue writes~
My 10+ yr. old wisteria had numerous large blooms the first early last year and several blooms later on. It had one seed pod (1" x 8" lumpy & fuzzy on the outside) The seed pod is still hanging on the vine. Can the seeds still be planted? I live in west Michigan (about 2 hours west of MSU) so you're probably familiar with the climate conditions. I noticed you told another person to plant late in the winter in specific potting medium, I am assuming that is indoors?

A. Yes, you are correct. Sow the wisteria seeds [or any other seeds one has] inside in the late winter in a good, light, fresh, sterilized mix. Some garden centers carry propagation mix which is made from finely milled peat moss with fine perlite and vermiculite added. This is an excellent medium to start most seeds.

Moisten the mix with water [some needs to be placed in a pail and soaked overnight]. Place into trays, flats or small shallow pots and squeeze out excess moisture. Wisteria seeds are large, so they should be covered lightly. Other seed which is quite tiny needs to be sown right on top of the mix.

Cover with plastic or a pane of glass. Place in filtered mild light, not hot or direct. If moisture beads appear, prop the lid to air out for a couple hours.

Soon, the seeds will sprout and the lid needs to be removed. Increase light and start to give them a 1/4 strength fertilizer after the seedlings are several inches tall. Watch the watering. Do not allow medium to dry nor keep it soggy as they may suffer damping off, a fungus which cuts the stems at the soil line.

Plant the seedlings into individual pots or cell packs when large and then into the garden beds after your frost date.

Shelley writes~ I have always loved the beautiful wisteria flowers and I am finally going to plant one this spring. Can I plant it alone or do I have to plant it against a structure to grow on such as an arbor? I was told to just plant it and keep wrapping the long pieces back around it and it would be OK. Is this correct?

A. Certainly you could do that. It will take some diligent attentiveness to the vine stems making sure that they do not dangle down onto the ground and are secured up around their neighbors.

Nothing is written that wisteria will not do well and bloom without support. If that is what is best for your particular location, then go for it! You could use string loosely tied, and checked often to make certain that the stems are not being strangled by that support. A green string or twistem color will blend right in with the lovely foliage.

Ron writes~ How do I grow more Japanese Wisteria vines from the one I have by a cutting?

A. You can very easily take cuttings from your wisteria vine and propagate them in a light sand mix with some perlite, moistened, and kept in low light and well-watered. Do not allow to sit really wet or they will rot and do not allow direct sunlight due to heat and burn, nor darkness as they need light on top of the stem growing points to send the chemicals down to the cut to stimulate roots. Allow roots to get at least 4-5" long before potting them up and growing until large enough for your garden beds.

Wisteria can be easily propagated by layering the vine by burying sections a foot or so apart in soil that has been loosened for easier rooting. Each buried section of the branch should be adjacent to a bud or shoot that is not buried. The shoots will develop into the new plants. Cover the buried parts with flat rocks or an organic mulch which will speed rooting by keeping the soil moist. By the end of the growing season roots should have formed at each buried section. Dig them up the following spring and cut the rooted sections apart.

Dormant shoots can be grafted onto pieces of roots in a warm greenhouse in the spring. The lower branches may be layered in the spring. Root cuttings may be taken and seeds may be sown.

For more cultural info, check out:

http://pages.prodigy.com/gardenshop/green51.htm

Pattie writes~
When you refer to the wisteria seed, are you referring to the "seed" inside of the pod or the whole pod full of "seeds". We have a beautiful wisteria and it gets lots of pods (full of seeds?; We would like to plant some of the seeds and start new plants. We are not sure if we are to plant the whole pod or take the "seeds" out of the pod and plant them individually.

A. Very good question. The seed pod has many seeds inside, depending upon the variety and fertilization. This is true to most flowering plants, though some have only one or two seeds inside.

It is best to allow the seed pod to dry in an envelope in a cool, dry, dark spot. Once the skin ages, it will split and toss out the seeds. The envelope will contain them. In nature, this is a method to disperse seeds at a distance. Once the seeds are dry [usually a shade of brown, maybe mixed with green], sow on top of a sterile, moistened, fine mixture of 1/2 perlite and 1/2 vermiculite. Some nurseries or centers sell propagation or seed starting mix. Cover with a clear pane of glass or plastic wrap. If moisture bubbles inside, place ajar for a couple hours to aerate the container.

Within two weeks, you should see tiny green flecks. Let the seedlings grow to a manageable size before transplanting into small flats or pots. When sturdy, move outside for several hours at a time to harden them further. Soon, you will be able to transplant them into the garden where desired. Keep a close watch on them for pests, drying out, animals and kids. A small border fence can be used or a large glass jar overturned on them until growing well. I hope that helps you.

Julie writes~
We have a wisteria which is a 20 years old growing on and round our bungalow. It has flowered profusely in the past 10 years and my husband has pruned it twice a year according to our 'book'. This year the flower buds formed, and nothing else has happened. No flowers, no leaves, nothing. It looks as it does at the end of winter. The flower buds, which didn't get any bigger than a thumb nail, have dried out and crumble when you squeeze them. The leaves didn't show at all. What can we do?

A. This problem sounds like low moisture in the air, called Humidity. If you experience a dry spell, the buds actually blast. That is what your description sounds like. If it is not the moisture in the air, then it could be a result from drying of the soil. If it went even a short time with low or no water, the roots could have become stressed, leading to bud drop and therefore no flowers.

It is not a disease, but happens to all sort of flowering plants, including fruit trees. In the future, as the flower buds set and swell, every couple days check the soil moisture to a depth of one foot with a pole to ensure that there is sufficient water there to prevent root stress. This is a very crucial time for flower buds.

Continue to water the vine well and give it a dilute fertilizer every two weeks to encourage foliar growth. Do not abandon this prized plant.

Jamie writes~
I need some advice as to winterizing my 1st year blue Wisteria Vine. It is growing on a steel arbor and is 6 to 7 foot tall after only 5 months. I live in southern MN. and need to know what I can do to protect this vine and how to trim it!

A. There are several tips I can provide.

Cut off all fertilizing as this promotes foliage and you do not desire fresh, young growth. You want to harden the plant to prepare it for harsh temperatures, wind and snow.

Mulch all around the vine very well, to a depth of a 1/2 foot. Use healthy dead leaves or buy some mulching material from a garden supply company. Avoid any acidic leaves as oak and pine, since they will lower the soil pH.

Do not prune any stems even if they appear dead. wait until spring for that chore, as the brittle stems may actually be alive and sprout foliage and flowers next year. Secure all stems safely but loosely to poles, trellis or arbor so that wind will not blow them down and snap the stems.

Check locally for a spray to use for winter dormancy since MN. is a very cold climate and it may be very helpful. Find a reputable, knowledgeable sales person and ask an opinion.

Nancy writes~
I bought a house that has a very well established wisteria plant. It had been trained to go around the house on the eaves, about 55 linear feet. I am having a new roof put on and may need to remove it from the house. How far down can it be cut to still survive and also to be retrained on an arbor? I don't want to cut the trunk too low because it is close to the front door and would look too harsh. Any advice would be helpful.

A. It sounds that your plant is quite old and therefore has a deep, wide-ranging root system with thick old trunks jutting out of the ground. It would be difficult to kill the vine, so a hard cutback would be very good. Saw the trunks off at a height of 4-5 feet, shaping the side branches as you trim. In most parts of the USA, now is a good time to prune harshly, so that it gets hardened for the upcoming winter and lower temperatures. Do not encourage any new tender growth or give the vine fertilizer until spring when new growth pops out. Then begin a weekly program of dilute feeding high in Nitrogen.

Kathy writes~ We have a young (1 yr / 4 ft) Wisteria tree in the back yard and are now considering a pool. I want to move the tree to our country property but need to make sure to get all the vine so as not to threaten the pool. How can I be sure when we dig the tree up that we will not leave a root that will regenerate and damage the pool or plumbing?

A. You really cannot I must say. It is a very fine idea to rid yourself of this spreading vine near a pool or foundation. Their tiny roots spread and penetrate very much like Weeping Willow trees. Since your vine is only a year old, there should be little problem controlling it with supervision during the upcoming season. Dig out and around the vine by around 3 feet further than the branches spread. Dig very deep to get as much root as possible. Do not pull on it or snap it, as you will leave behind roots and places where it can regenerate. Make sure the soil is soft and pliable by soaking it well a day or two before the task. As the temperatures warm and rain follows, watch for sprouts where the vine was removed. Again, repeat the above method and eliminate these young stems before they can establish a good hold.

Crissy writes~ Hello, first I love your gardening site. Second I'm a beginning gardener and will be asking you lots of questions. You seem to be a wealth of information. I have a 2 year old wisteria vine that is in need of moving. Hindsight being what it is, I realize now I put it in a bad place. It is winding itself between the siding on my house and it is also on inadequate support. I purchased an ordinary wooden arbour from the local Kmart and now it is leaning terribly in two different directions. Forward and to one side. Please give me some helpful tips on how to go about this task. When should I do this, Spring or Fall? How far back should I cut the vine? It is really wrapped around the trellis work on the arbour.

A. Wisteria climb best on arbors and related constructions. Use sturdy, durable materials such as galvanized wire, tubing or wood. Copper or aluminum wire or tubing are preferred over other metals since these do not rust. Do not plant wisteria where stems can invade and clog building gutters. Some annual pruning is required to maintain plant quality. It is not advisable to allow the vine to grow randomly and take over surrounding plants and structures. Pruning will help reduce the vigor of the vine and promote flowering. To train plants on an arbor, select a vigorous, upright stem to serve as the main leader and attach this to the support. Make sure the supports are securely dug into the ground, to prevent this wobbling you have. Remove other side shoots. As the main leader grows, it will develop side branches that will then produce more shoots and the flower buds. Continue to train the main leader upward and the new side branches as needed to form a framework to fit the allotted space [allow about 18" between side branches]. Pinch off the main leader when it reaches the desired height. Here is an excellent site for descriptions and drawings of pruning throughout the season, much to involved to print here:

http://ohioline.osu.edu/hyg-fact/1000/1246.html

Tamara writes~
I am in zone 5. I just ordered one Alba wisteria and one Blue Sapphire wisteria. I like the look of dwarf trees and I also like espaliered trees, so I wonder, can I train the two vines to wrap around each other? Also, we plan on moving in about 5 years, so I do not want to plant them in the ground and leave them. How big a container do I need for the two vines?

Once established, Wisteria grow rampantly. They need support even when grown as umbrella-shaped topiary. You can grow it in a large whisky barrel or other large container if you must. This practice is questionable as they can be quite aggressive growers. Over an arbor is perfect. Every wisteria needs regular hard pruning both to keep the plant from overwhelming everything and to promote good blossoming. Those whippy branches can grow a 10-15' in one season. They can pry shingles off your house or roof. Plant your vine near a very sturdy trellis or arbor. Just make certain that it has something hefty to lean on that will not pull apart or fall down. Many commercial trellises are simply too flimsy to suit this plant. Wisterias like well-drained acid soil and, once established, do not need a lot of supplemental water in summer. They do not need fertilizers. They seem to resist pests very well.

Debi writes~
I have a 10 year old wisteria that is large and very healthy. I have to remove the plant at our rental house and wanted to transplant it at our house in the country. How can this be done and will my beautiful wisteria make it?

A. Cut back to about 4" from the ground after flowering. Wisteria is a borderline weed and tough to hurt. The best time to transplant wisteria is during dormancy just before it leafs out (late winter to early spring). If the vine is large and unwieldy to move, plan on cutting it back to a manageable size. Wisteria is quite tolerant of hard prunings, so do not be too shy with the pruning shears. If the plant is old, expect to encounter an extensive root system when you dig it up. You do not need to lift all of the roots because wisteria actually benefits from root pruning, an excellent way to keep its rampant growth in check. Deciduous broadleaf, height: 25-30'. Shiny, bright green leaves turn yellow in autumn. Fragrant, pea-like flowers bloom in clusters 8-36" long. Zones: 4 to 9 in partial shade to full sun; wet, moist, or dry soil in sandy, loam, or clay; pH Range: 4.5 to 7.0. Suggested uses for this plant include climbing vine, specimen plant, and screen (with support). Transplant with care. Slow to establish. For best results, transplant in deep, moist well-drained loam soil. Too much nitrogen fertilizer stimulates vegetative growth and reduces flowering. Vines requires a strong support but little care once established and flowering well. Scale insects can be a serious problem. Wisterias are excellent vines for training to grow over patios, arbors, or pergolas. Suitable for bonsai. Cultivars: `Alba' has 11-inch racemes, moderate fragrance, and white leaflets. `Longissima Alba' has 15-inch racemes, good fragrance, and white leaflets. `Rosea' has pale-rose, purple tipped leaflets with long, 18-inch racemes. Related species: W. sinensis (Chinese Wisteria) is a more vigorous grower and has a blue-violet flower, but is not as fragrant.

Assistance from: http://www.ext.vt.edu/departments