Rhodos won't bloom

Alexandria, VA(Zone 7b)

Rhodos are five years old, all the same type, zone 7, planted on a hill 12 feet high and 35 feet long, dappled sun, adequate mulch and moisture, little fertilizer, marvelously healthy except for no buds or flowers. Twenty percent at one end are blooming and the rest don't even have flower buds--just new leaf growth. HELP!

Caldwell, NJ(Zone 6a)

You need to stress the plants. Cut back on watering after July. Prune heavily immediately after bloom. Give potassium fertilizer the year before. Many Rhododendrons do not bloom well until mature and many bloom every other year. Lack of light is another cause of poor bloom

Alexandria, VA(Zone 7b)

All good advice, many thanks!

Hurst, TX(Zone 7b)

Except that if you do not see flower buds by now, then it is possible some pest (squirrels, Bamby, etc) ate the buds during the winter.

Alexandria, VA(Zone 7b)

There was no scar or spot where an old bud was. The 3 to 4 leaf shoots are growing like gang busters. My guess is it is too much shade, but I am doing two soil samples.

Hurst, TX(Zone 7b)

If the plant is not producing flower buds, fertilizers may have kept it on growth mode during the Fall and sudden frosts eventually killed the buds. If this were to be a possibility, I would recommend stopping fertilizers beginning around July-August.

Pruning after the flower buds have formed can also cause a lack of bloomage. Prune after blooming and before July-ish.

Dense shade can cause this problem too but it depends on the variety. Some specimens will still produce some bloom in dense shade (albeit at reduced levels).

When you get the results of the soil test, check the pH and the phosphorus (helps develop roots and flower buds) and pottasium levels (hardiness to heat/drought/cold and a good supplement before winter).

Alexandria, VA(Zone 7b)

Good advice on checking the phos. and potassium!

Plainwell, MI(Zone 5b)

This is whats happening to mine also. So dissappointed when they do not blossom. Mine gets afternoon sun and dappled shade most of the day. The tag says part shade to shade. Should blossom where I have it. How far back is a hard prune??? Just as an FYI. I hope you get the "bugs" worked out of yous also..6033! I see the beautiful rhodies all over and want mine to look like those! Ronna

Hurst, TX(Zone 7b)

Hard prune is about 1/3 of a plant.

It would be so nice if we could hook up the shrubs to a PC and let them notify us when there is a problem that would prevent bloomage but alas, maybe on Windows Version 38926.4b. In the meantime, try determining if the plant does not generate flower buds at all or if the buds are being aborted (or are being eaten by squirrells or Bamby). Based on that, one can take some sort of appropriate action.

Plainwell, MI(Zone 5b)

No it looks like newer growth on top. But there were no flowers at all. So should I prune it now? And give it some miracid? Or just prune? I seen other friends rhodos and theres had great big buds on top my looked nothing like that. I did not prune last year where it was done blossoming. I did not know we were suppose too. That couldv'e been my downfall. Ronna

Hurst, TX(Zone 7b)

Well you may have just hit on what is causing your problem with bloomage, Ronna. Miracid is not a good fertilizer to use with plants like rhodies and azaleas. If you look at the NPK Ratio on the product, you willl notice that Miracid is actually quite high in nitrogen, about 20% of it. Nitrogen rich fertilizers cause a lot of plant growth and supress bud production. They keep the plants in growth mode instead of letting them go dormant. It may work well in potted plants since a lot of it would leech away. But for plants in the ground, I would recommend either a general purpose slow release chemical fertilizer like Holly-tone or an organic one like cottonseed meal. To compare, Holly-tone has a NPK Ratio of 4-3-4, which means you get only 4% nitrogen. All that tender growth can get killed during the early Fall frosts because the plant has not reached dormancy.

Rhodies and azaleas are not high feeders like roses. They just slumber along and normally like to eat off the decomposing mulch. So if your soil has no defficiencies, you would not need to fertilize them, just maintain 3-4" of acidic mulch at most times and keep the soil moist.

Try only tweaking the fertilizer program. And prune only if you need to address some other issue.

Plainwell, MI(Zone 5b)

I have never used the miracid on it. But was told that I should by someone. So all I should do is prune?

Hurst, TX(Zone 7b)

Get the soil test done and apply fertilizer before the end of June. Prune before the end of June if you need to correct some problem with the bush.

The do the usual... Maintain 3-4" of acidic mulch and keep an eye on the soil moisture, especially after the plant begins to develop flower buds in July or thereafter. Keep the soil moist -not wet- as best as you can.

Then check the nitrogen, pottasium and phosphorus levels when you get the results of the soil test. They sometimes add comments if you indicate why you want the soil test done (answer: "blooming problem with rhododendrons")

Once you can identify the flower buds, monitor (1) how many you see (a lot? not enough?) and (2) observe if they abort or are eaten by garden pests (squirrels, etc). If you notice a low production of flower buds, soil moisture is ok and the soil tests shows no problems then I would conclude that they may need more sunlight. A high number of buds that then literally disappears might indicate squirrels at work. Aborting of buds might indicate a problem with winter temperatures/winds or a problem with soil moisture (too much or too little).

Luis

Plainwell, MI(Zone 5b)

Thanks a whole lot luis_pr.

Hurst, TX(Zone 7b)

You are welcome, Ronna.

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