Wisteria and coffee grounds

Question from Elgy:
Help! At least one life is at stake! I bought a lovely wisteria a month ago, despite bad luck with wisterias in the past.
I chose a very deep pot and a very sunny spot in my back yard this time … then I went away, trusting in kind neighbors to water it. Well, they didn’t, but it thrived anyway. To compensate I started regular watering with mixed water and coffee grounds on my return. Then it lost all its blossoms, the leaves yellowed, some leaf tips went black, and it began to die… Could it be a) San Francisco summer fog or b) high winds or c) too shallow a pot or even d) too much coffee? Could I make a hole in the concret with a kanga hammer to give it better drainage?

Answer from Pat:
Wisterias are prone to root rot, but your’s may have succumbed to other problems as well.

To begin with, please read on this blog what I’ve already written on wisterias:
https://patwelsh.com/wpmu/blog/garden-q-a/root-rot-and-wisterias/

Don’t put coffee grounds on wisteria. Coffee grounds have a quality similar to tea leaves: They are acid. Wisterias are not acid-loving plants. Knowledgeable gardeners throw coffee grounds and tea leaves on top of the ground over the roots of acid-loving plants, such as camellias, azaleas, and blue hydrangeas, because in this situation the tea leaves and coffee grounds become part of the mulch, and they may gradually help acidify the soil.

Neither coffee grounds nor tea leaves are fertilizers. Balanced fertilizers are composed of nitrogen, phosphorus, potassium,and trace minerals. Coffee grounds and tea leaves are composed of plant fibers. They are not even rotted or composted, but it’s fine to throw them onto the ground around acid-loving plants or into the compost pile as part of one’s complete composting process. Compost piles and compost bins are ways to rot organic matter so that it can be safely combined with soil without subtracting nitrogen from the soil in order to rot.

Any kind of un-rotted organic matter you add to garden soil or to soil in a pot will have the tendency to subtract nitrogen from the soil in order to rot. So it’s fine to throw coffee grounds on top of the ground if the plant beneath is an acid-lover, but—here’s the kicker—wisteria are not acid-loving plants, and adding coffee grounds every day, yes—um—uh, you are DEAD right. It’s over-kill. (Grin!)

Wisterias, are adapted to growing in almost any kind of garden soil as long as it’s well drained. They should be grown in the ground and fertilized with a mild fertilizerm during the growing season of the first three years of life to get them started. After that no fertilizer is needed. They also need careful pruning and training especially during youth but continuing throughout their life, as explained in detail in my organic book, pages 188, 31, and 406.

Your major problem is trying to grow a wisteria in a pot. A pot won’t give a wisteria enough room for its roots. Growing wisteria in a pot is an iffy proposition in the best of circumstances and if the pot is sitting flat down on a patio, it’s quite likely roots will soon clog the drainage hole and in their effort to escape make a little water-proof mat below the pot, sealing drainage securely shut. Without good drainage wisteria will die—Clunk!—just like that. (Setting patio pots up onto “pot feet” can prevent this problem.)This is my guess as to what happened to your plant or else the roots simply got too wet because you watered too often and root rot set in. This is instant death to a wisteria.

Regarding wisterias, you might enjoy reading an illuminating experience I had many years ago—Chapter 7 “The Wisteria that Wouldn’t Give Up” in my book called “All My Edens, a Gardener’s Memoir”, Chronicle Books, 1996, long out of print but you can still find good used copies on the Internet. It will teach you a lot about wisteria.

Your idea to use a kanga hammer is the best idea yet. If you can, first read all I say in my organic book on the subject of wisterias. (See the index on page 456 for many page numbers.) Be sure to purchase a grafted variety or it won’t bloom for many years. Then make a hole through your patio with a kanga hammer and plant a grafted wisteria into the hole. Be sure to buy a grafted one and take care choosing a good variety, having first learned the difference between Chinese and Japanese wisterias so you can make a sensible choice.