What do lilacs want?

[LCBMAX]

Our lilac bushes are thriving and growing, budding this week, but in the 4 years we've lived here, scarcely a blossom have we seen. They often get frozen after budding so I'm ready with blankets to cover them this year when I see the next frost coming.

Any thoughts on what else they would like?

Thanks!

-bereft lover of lilacs

[Lovesong]

Well, in my experience lilacs are really one of the hardiest plants in my garden. And I live in Sweden, in the inland, where we get really cold winters and really unstable springs, where one day it is almost summer warmth and the next it is snowing. We have never had a problem with our lilac buds freezing.

It might be that you've got a variety that thrives in warmer climates. If so, covering them is a good idea. Once they grow bigger, and can't easily be covered, you might want to try investing in a small sprinkler system set on a fine mist if you live in an area where this is possible. The continuous water mist will keep the buds from freezing if we are only talking the occasional frost night.

Generally, my lilacs just grow. I do cut away dead branches, and do keep them in check (or else they would soon overtake my whole garden with young plants) but really, they are extremely easy going and nice plants.

[LCBMAX]

Oh, thanks so much for replying!

When do you cut them back? Pre-budding, mid-flower, autumn die back time? 

They may very well be overgrown, ok, I know they are, so perhaps cutting back will give them more energy.

As expected, 70 degree F 2 days ago, and snowing right now! I've got all the blankets covering as much as I can reach...

[DoubleDouble]

You can cut them back after blooming. If you prune them in Autumn you'll clip the next year's flower buds.

Also, lilacs like lime - is your soil acidic? Do they have enough sun?

How old are the plants? Maybe they need a "rejuvenation pruning"?

[MariesMama]

They may need to be pruned - what zone are you in?

[LCBMAX]

Technically we are in zone 7 but I think we live in a funny little 6b pocket of our 7a area.

I'm sure they do need pruning. There are non-blooming branches even now while some are budded out, and some of the plants seem to be very well established (read: overgrown), so I'd assume pretty old. My guess is more than 7, some maybe even more than 10 years old.

I don't know yet if our soil is acidic - I've been told that I can take a sample to the local Agricultural Extension something something... locally, that might mean a funny and long adventure with no promise of results.

I see from google searches that I should not be intimidated by the project of getting the soil tested, maybe by a take-home kit from a garden store. I'll try I'll try I'll try! It's a new world for me out there. I met my first "cutworm" today, really, first ever, and I'm >40!

I really appreciate your help to someone with not even a pale green thumb!

[lmonter]

Hmmm, I've never dealt with a fussy lilac before. 
I live in a chilly zone 5, our lilacs go bonkers up here.  They love acidic soil.  Seriously, love it. 
They don't tend to bud before mid May, about when we have our last hard frosts (we can't put basil/tomatoes/peppers in the ground until Memorial Day though).  We've hacked our lilacs practically to bits on and off through the year, and they just keep growing back and back and back.  They only get watered from the rain, I've never really made an effort with them.  They were fully established when we moved in 8 years ago though, and they're about...  12 foot monsters now.  We also got a random bird-poop-seeded dark-purple lilac a few years back that we yanked and I put in a pot, we'll see in a month if it overwintered okay in the pot.
 

[LCBMAX]

That does make me think that the water and weather issues are as important as the soil - we are in the high desert with deceptively high daytime temps well before the last frost, so they are likely getting faked out. And of course, desert = dry, but so far we've got that adjusted with consistent drip system work.

Today will look for a soil sampler!

[SweetSilver]

Lilacs adore chilly winters.  Winters that get cold and stay cold.  Places like the coastal NW they grow and bloom fine for the most part, but I grew up in Spokane, WA and they were in an entirely different class there.  Lilacs went berserk.  

Still, to not get much bloom at all.....  

Is it budding, just not blooming?  What kind of fertilizer to you put around the garden?  Think not just of what you are doing for the lilac, but for the garden surrounding it.  7-10 years is not too old for lilac branches.  A shrub will do well to occasionally have its old branches replaced, but 7-10 years is in the prime of life for a lilac branch.  Pruning will not necessarily encourage more blooms in lilac.

Lilacs do fine in acidic soil, but prefer it towards neutral or the alkaline side.   But we have acidic soil where I live and they do all right (not to the standards of my childhood, though.)

If it looks like they *bud* nicely but don't *bloom* I would suspect your high desert springs.  Sweden and Spokane might get cold winters and springs, but I imagine in the desert you will be seeing quite warm spring days with frigid cold nights.  I think that would be confusing for lilacs, as it would with fruit trees and other shrubs.  

But are you getting buds at all?  If not many, I would first consider the cultural practices of the rest of the garden.  Overwatering, overfertilizing.  I seriously doubt that desert soils are going to be acidic.  Too alkaline perhaps?  (Too saline, perhaps, especially if you irrigate.  But I think that would affect the plant as a whole.)  All possibilities.  My first guess in this line of thought would be too much nitrogen if the plant looks healthy ("overgrown") but isn't blooming.  Sometimes young shrubs are slow to get going, but I haven't seen lilacs do this, but then I haven't seen lilacs in desert areas outside Eastern Washington.

For me, the answer lies in whether or not the buds it makes are able to blossom, or if the buds just aren't there at all.

Zones are funny.  We live in the same USDA zone as you do, but I'm sure our springs and winters don't look much like yours at all!  A better guide, I think, is the Sunset Western Garden Guide, which has 24 zones.  I think I am in their zone 4.

[LCBMAX]

Waaaiiiiit just a second here.... could it be that they love acidic soil in areas that freeze consistently til spring is really there but love alkaline when the spring temps vary a lot?

Some say acidic, some say alkaline.... oh dear. This is where a tentative gardner like me easily discourages herself...

[SweetSilver]

Originally Posted by LCBMAX 

Some say acidic, some say alkaline.... oh dear. This is where a tentative gardner like me easily discourages herself...

The reason is that lilacs do pretty well in most situations, which is why you will see them grow well from Sweden to Seattle, Georgia to New Mexico.  Horticultural books will mention their love of soils on the alkaline side of the spectrum, but in our acidic PNW soils they do just fine and everyone loves them and plants them.  They also prefer really cold winters, but again they do just fine where it is not particularly cold.  They like drier springs, but our region's wet springs only make the bloom time a little shorter.  I've lived in places where they really thrive--when I was a kid, the Spokane Lilac Parade was a big deal-- and also in regions where they do well enough that if you haven't seen them where they go bonkers, you wouldn't know there was a difference.  
 

[SweetSilver]

Double-checked my Sunset Western Garden Guide, a must-have book for those of us west of the Rockies.  A couple of things it mentions.  S. vulgaris, your standard lilac, will take a few years to produce the best blossoms.  Some species (not S. vulgaris) bloom on new growth, but if you haven't pruned these at all, that won't be an issue.  The hybrid S. x chinensis does better in mild winter/ hot summer climates.  They mention regular water, tapered off towards fall for areas with milder winters to force dormancy.  

Though I mentioned soil pH, I don't think this is an issue with your lilac.  It's possible that the soil is way too acidic or alkaline, but you would be seeing this affect the plant's growth.  So, I think soil pH is a red herring.

No, I think you were on the right track with your area's warm days/ cold nights.  That's *if* it is budding out but not blooming.  If you don't have many buds in the first place, but the ones that are there bloom just fine, then either the shrub is too young (?) or more likely is getting too much nitrogen from the surrounding lawn or garden. 

Edited to add:  One useful thing you can do is find someone else's lilac and see how it is doing.

Edited again:  the website for the Arnold Arboretum states that lilacs prefer "slightly acidic to alkaline" soil pH.  So, somewhere near neutral apparently.  Thought I would check to make sure that what I remember has some actual basis in truth.

Edited by SweetSilver - 4/9/12 at 5:41pm

[EarthRootsStarSoul]

A little off topic, but I just had some lilacs start growing in my yard that I didn't plant.  I don't know where they came from, and they probably have been there a few years and are just blooming for the first time right now.  I didn't recognize them as lilacs until they flowered.  They have pure white flowers, which is surprising!  I've never seen white lilacs.  I wonder if it has something to do with the soil pH or some other condition, or if it is just a variety that is white.  Since there are some great big pine trees in my yard, I assume the soil is acidic.  It's also marshy and wet, partial to full shade.  I'm in zone 4 or 5, with deep cold freezing winters. 

[SweetSilver]

It's the variety that is white.