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.