Take Care Of Wisteria Tree

Wisteria tree

A Wisteria tree is not a "real" tree in the sense that you will find them growing wild in some forest. They are grafted plants. A Chinese Wisteria vine is grafted on top of a standard tree trunk and root system.  The standard trunk is as tall as the plant will ever get and the vine part hangs down and gives incredibly fragrant flowers in early summer.  The flowers are spectacular and look interesting in a mixed border of taller perennials.

Prune Vine

Having said that, you do have to 1) take care of this Wisteria tree and give it what it wants as a tree and 2) you have to prune the vine portion yearly to ensure it continues to flower

Sunlight Needed

This plant will grow best in an area that receives six full hours of sunshine a day.

 Remember that Wisteria vines themselves prefer to be out of the very hot mid-day sunshine. Give the wisteria tree lots of morning sun and late afternoon sun but do try to keep it out of the hot mid-day sun if possible.

This is particularly true in warmer gardening areas where we see these plants sold commonly in garden centers.

Hardiness

They are not as common in northerly areas because the wisteria tree is not reliably hardy anywhere north of zone 7.

First Planting Step

If you get your wisteria tree bareroot from a mailorder nursery, the very first thing you want to do after unpacking is to plunge it into a pail of warm water and let it soak for a few hours. This should rehydrate the roots. 

While it is soaking, dig a planting hole wide enough to spread the roots without turning them or forcing them into un-natural positions. 

The hole should be deep enough so that the crown of the wisteria tree (the crown is where the stem meets the roots) is planted one inch below the surface of the garden soil.  When you install the plant note that the roots of the standard are often quite brittle and if you break them, you’re setting your expensive wisteria tree back.

Planting Techniques

Work soil back into the hole, watering it as you go to ensure there are no pockets of air space there and to create a muddy root hole. Do make sure the crown doesn’t sink in this process (it tends to do this unless you hold it up with one hand and backfill and water with the other) 

After the roots are backfilled, I recommend firming the soil by pressing down as hard as you can around the trunk.  Some gardeners make a small dike around the plant to hold in the water but I have never gone to this extreme.  The last step is to soak the entire area thoroughly again. You want to muddify this plant into the garden.

Staking

This plant is a bit of a wuss in that it does want to be staked. Those big flower heads can really push the trunk around, particularly if you live in a windy area. 

Drive a good stake about twelve inches into the ground right next to the trunk (about an inch or so away from it) and then tie the trunk to the stake with some soft material.

I think old pantyhose make the best tree tying material known to man.

Do not use small string or wire as it tends to cut into the bark.

Experts growing this tree usually increase the size of the stake (in thickness and strength) as the trunk expands (remember it won’t get any taller) in width.  The tree will always need staking. Up here in the north, we simply buy new trees as we kill them over the winter. This is somewhat more expensive than buying new stakes but much cheaper than moving South.

Trick to Establish Successfully

The trick with establishing any new shrub or tree is to water it several times a week for the first few months.  At least one to two inches of water is needed by this plant every week for the first few months and then one inch a week thereafter.  Mind you, you only have to water it if you want it to grow.

Overfeeding

Sometimes people write and ask why their wisteria isn’t blooming because they are feeing it well and fertilizing the devil out of it.  That’s exactly why. Wisteria do not as a rule like to be well fertilized. A shovel of compost in the early spring before the plant really starts to bud out is all the food it requires for the entire season.

Overwintering

When it comes to Overwintering this plant, I’d recommend you ship it to California or take it there yourself for a winter holiday. Failing that, you have to protect both the trunk and the vine parts from wind, cold and ice that will play havoc with the branches.  Good luck. The colder you are, the more you have to protect it. Or, grow it in a clay pot and put it in a cold cellar for the winter. 

Pruning

And now we come to the last and least understood part of getting this plant to bloom.

Folks, it is all about pruning wisteria. The trick with the wisteria tree and indeed vine wisteria is to prune them hard. In the case of the wisteria tree, you want to maintain the globe shape and not allow the branches to get too long. So, during the summer months when the vines start to really stretch out – prune them off to where you like the look of the leafy growth.


And in the fall, just around your frost date or winter onset when the leaves will fall, prune the plant back to five to six shoots per main branch. In other words, the first five or six shoots off each branch are left and the rest of the long branch is removed.

These in turn are cut back to about six inches long leaving five or six buds on each of these branches.  You wind up with a short stubby (rather ugly looking) wisteria tree. Much like the open framework of an umbrella.

And the nice part of growing a wisteria tree is that if you don’t kill it over the winter, it will grow like stink next year so any mistakes you made this year will disappear.

Good luck!