1947jd
Full Member
Posts: 10
Joined: Sun Apr 11, 2010 7:32 pm
Location: Western Slope Colorado

Lilac not blossoming

When I moved into this house three years ago last November there was a huge clump of lilac beside my back porch. It had several extremely long lightly leafed branches growing out of it. Our county extension agent recommended cutting the entire bush back to about 2' high which I did. In the three springs and summer seasons since, the bush has grown several new shoots that are now nearly 6' high but have never blossomed. I've trimmed out what look like suckers. A second much smaller bush on one corner of the house was trimmed the same way and has blossomed every year with increasingly more and more beautiful blooms. Is there a fertilizer that would encourage blossoming on the bigger bush or am I just being impatient with the big bush?

luis_pr
Greener Thumb
Posts: 815
Joined: Sun Jul 05, 2009 12:31 pm
Location: Hurst, TX USA Zone 7b/8a

How much sun does it get, 1947jd?

How much fertilizer do you feed it? And when do you start and stop fertilizing? Does lawn fertilizer get into the root area of the lilac?

Does it have any moisture issues in the Fall and Winter where you live?

Do you prune this bush? If so, when do you prune?

1947jd
Full Member
Posts: 10
Joined: Sun Apr 11, 2010 7:32 pm
Location: Western Slope Colorado

Lilacs not blooming

Lots of questions luis_pr!

The non-bloomer is on the NW side of the house, between the house and a willow - lots of light but only a few hours direct sun afternoon.
I haven't fertized the bush at all - there's no lawn around the bush, it's a small area so I've woodchipped the area all around it.
Fall and winter moisture are up to Mother Nature - some years a lot, some years not.
I have only pruned in the fall.
Does that help?

luis_pr
Greener Thumb
Posts: 815
Joined: Sun Jul 05, 2009 12:31 pm
Location: Hurst, TX USA Zone 7b/8a

I am not sure if it gettting enough sun then. Sometimes indicrect light or dappled sun can help. About 5 hours of sun would be ok. The one that I am growing here HAS to get less than 5 hours because the leaves will fry otherwise during the hot summer months so I expect bloomage to be affected by that. Can you possibly raise the canopy of the other tree that is nearby?

Another concern is the moisture issues. Most lilacs develop flower buds on old wood (the exception being rebloomers). One possibility worth considering is moisture issues that cause the tree to abort the flower buds. This occurs when the tree can no longer support flower buds due to the lack of moisture. Since you do not water in Fall and Winter, this could be a problem that gets compounded if it has pests that stress the shrub. Have your three years in that house been dry in Fall and Winter? A minor solution to consider is to mulch the area around the tree well with 2-3" of mulch. But you ought to consider some source of moisture during the dry Fall/Winter. Have you considered drip irrigation or colleting water in rain barrels for the lilac?

Another possibility.... How is the soil in your area? Have you had a soil test done ever? Lilacs prefer alkaline soil so I was wondering if you had any mineral deficiencies. You can check for soil alkalinity (or acidity) using a soil pH Kit. Some of the kits can also alert you to a phosphorus deficiency, which could cause lack of blooms too.

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