Blooming Jasmine
April 4, 2011 6:24 AM   Subscribe

My Jasmine is broken. How can I persuade it to blossom?

How can I get my Jasmine to flower?
It's a good sized plant, 3 or 4 years old, in a good sized pot. Well watered, in a North facing window. The only flowers I have seen on it where when I bought it.

I've tried nurturing it and cajoling it to flower, but to no effect. It's vigorous and green, a fine healthy plant, but loving isnt making blossom. Do I need to start abusing it; letting it dry out, turning it away from the light etc?

I'm not really a plant person, so any advice welcomed!
posted by BadMiker to Home & Garden (7 answers total) 3 users marked this as a favorite
Water regularly during spring/summer. Wait until the top half inch or so of the soil is dry between waterings, but never let the plant dry out completely. Water very sparingly over the winter.

Make sure it's getting plenty of potassium - something like a liquid tomato food is good during the growing season. I always dilute it a bit more than I would for tomatoes, though.

Trim it back after flowering. I cut mine back by about a third, and it flowers nicely every year.
posted by le morte de bea arthur at 7:27 AM on April 4, 2011

Smaller pot and cut back new growth, maybe? Plants wont blossom if there is sufficient room for root structure growth. Similarly, if the plant is expending all of its energy into its leaves, there won't be any growth either.
posted by Nanukthedog at 7:27 AM on April 4, 2011

I tend to abuse my plants when I want them to flower. This is particularly successful with passionflowers and some citrus and also shade-loving plants, and really with all sorts of tropical vines and things like stephanotis. (With gardenias, it's the opposite, you sort of want to feed them with lots of iron—and also not orchids, which are just petulant jerks, don't get me started, we're in a fight, and not speaking.)

There are lots of plants that, like people, feel the need to reproduce when they're threatened. My experience with jasmine is that it performs best when ignored and also when nibbled back by animals outdoors. When in doubt, I always turn my back on plants and find they surprise me. Since your selfish plant is indoors, you'll have to simulate the critter-nibbling with cutting, and letting it get good and dry each week will likely do some good. I also wonder if it wouldn't like a little bit of direct sun, if it's in a north window—depends heavily on which sort of jasmine it is.
posted by RJ Reynolds at 7:57 AM on April 4, 2011

Nanukthedog is right; if the pot is too big, it won't blossom. If it was blossoming when you bought it, they may have replanted it while blossoming, which means the current pot could be too big. Solution: wait another year or two.

The other things that matter here:

Light: if it gets hit by light at night, even a streetlight or a minute of light when you go to the bathroom... that screws up the flowering. It needs to be dark at night for this to work.

Temperature: if you can set it outside in 40-50F weather for one to three months, that will help.

More about light: look up "photoperiodism". It looks like at 72F and under, Jasmine needs long days of light (12+ hours) followed by long nights of dark (12+ hours) in order to flower. At 75F+, 12 hours of night, 12 hours of day.
posted by talldean at 8:04 AM on April 4, 2011

If you're in the Northern hemisphere (and especially as far north as your profile suggests), a north-facing window is probably not enough light for jasmine. Move it to a southern exposure, if possible, or western if you can't get that.
posted by joyceanmachine at 8:06 AM on April 4, 2011

le morte de be arthur is onto something with the potassium. Potassium (K) helps trigger flowering; nitrogen helps vegetative growth. Nitrogen will actually suppress flowering, if there is a sufficient amount.

Here is an aside: I used to have a water softener that used either sodium chloride or potassium chloride to reduce calcium in our very hard water. The NaCl was cheap, the KCl was expensive, so I used NaCl. The cold water in our kitchen was disconnected from the water softener, but the hot water was connected/softened.

One day I bought KCl instead of NaCl for the water softener. Within a week, my orchid, which had not flowered since we had brought it into the house a couple of years earlier, went into spectacular bloom. As best I could tell, the residual KCl in the kitchen tap from the hot water was enough to kick it into bloom, even though I used only cold, hard water for the plants. A couple of months later, I went back to cheaper NaCL, and the orchid lost its flowers about a week or two later.

Look at your garden supply for plant food that emphasizes flowering. It should have a relatively high proportion of potassium.

As other have pointed out, photoperiod is important, as is the strength of the light. Good strong light helps the plant make sugars (nom nom nom), but the darkness is important for flowering. My orchid in the above story was in natural light in the morning, and artificial light all day and into late in the evening, so YMMV.

Stress will help kick a plant into flowering, but it's not really necessary. That's a reproductive survival strategy. I have seen very old flowering trees burst into stunning displays...just before they die. You'd be better off just hitting the plant with some K.
posted by Xoebe at 5:27 PM on April 4, 2011

I'm guessing you mean one of the true Jasminum species, and not one of the many other plants called jasmine.

Not enough sunlight in your north facing window. Try an east facing window so it gets direct morning sun. Fertilizing it when it doesn't get enough sun or warmth is pointless, so take care of that first. Try and figure out exactly what kind of jasmine it is, so you can look up specific cultural conditions. The average jasmine species likes warmth and decent humidity. Avoid fertilizing with high nitrogen fertilizer.
posted by oneirodynia at 7:08 PM on April 4, 2011

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