Phoenix Hardenbergia is Crispy and Dessication is Setting inHelp

lieblingJuly 6, 2008

Dear Folks,

We planted three of these vines against our walls in March. Bought them from Moon Valley and were told that they did "great against any wall" and that "reflected heat was no problem."

Well, the two that get all day sun are suddenly, and I mean suddenly in the past week, quickly becoming crispy and look dessicated. They were doing very well up until then. There has been no change in watering (on a slow drip every other day) and nothing added to the soil.

We are very upset about this sudden turn and all we can think of is that its the intense heat days that have been hitting us for a month now and that the plants simply are giving up. We upped the water, but that isn't it.

My husband feels we should shroud the plants completely in shade cloth, but I don't know if this solves the problem (lack of sun could kill them too) in any long-term way.

Are they simply in the wrong location to make it through our summers here in Phoenix? The only one that's hanging in there (though not growing like the others were in the sun until those started to crisp up) is the one that gets less sun.

Please, any thoughts are welcome. I am calling another nursery, summer winds, tomorrow to see if they can offer some suggestions. They are big, expensive vines that were a bear to plant.

Thank you SO much in advance.


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haname(z9 AZ NE Phoenix)

Make sure you're not overwatering it. Let it dry out some between waterings and make sure the soil is well-drained. I have one I planted this year too. Is the wall where you have it planted facing west or south? That might be too much sun exposure.

Here is a link that might be useful: Hardenbergia violacea 'Happy Wanderer'

    Bookmark   July 7, 2008 at 2:29AM
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Thanks for your thoughts. I will cut back on the water and I have already untied the poor things from the wall and laid them down on the ground. I trimmed off the crunchy sections.

As for the exposure, the worst one is on an east-facing wall that gets sun from sunrise to about 4:00. The other one, not as crunchy, is on a south-facing wall that gets a little less direct sun, but once it's up, gets bathed until 5:00.

Like I said before, this has all happened over a period of one week. They were growing like mad until then. We've had so many consecutive days well over 100 that I wonder if it's a cumulative effect?

Shade cloth or no?

    Bookmark   July 7, 2008 at 11:03AM
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When watering it's important to apply generous amounts and then let the soil dry a bit before watering again as haname mentioned. Every other day is fine for newly installed plants, but after four weeks in the ground the watering interval should be extended. This time of year watering twice a week should be adequate as long as you are applying enough water.

The question is, how much water are you applying? You didn't say how long your system runs or what size your emitters are. If you have a one-gallon per hour emitter you'll need to let the irrigation run for at least two hours. That will apply two gallons of water. If your vine was in a 15 gallon container when planted it will need even more water and you may want to let the irrigation run for 3 hours. Of course, if you have different sized emitters, or multiple emitters you can adjust the time accordingly.

This time of year when air temps are soaring and soil temps are warm, keeping soils consistently moist creates a prefect environment for fungi and bacteria to cause problems with plant roots. Remember the watering motto.....deep and infrequent.

    Bookmark   July 7, 2008 at 12:21PM
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Hi, AZTREELVR (cute)

We have adjustable drips on for 40 minutes, every other day. It is very difficult to tell how much water is coming out per hour short of placing gallon jugs out there at each of the 50 emitters until they are full. They are probably around one per hour, but we can adjust them for more. However, I think your idea of less but more time is better for absorption.

I just called Summer Winds, and the nurseryman there said to pour SEVEN gallons on these plants at a time, three times a week (they're 5 gallons), and that the sun and reflected heat should never be an issue for lilac vines.

SEVEN gallons?

This is so confusing, because they are supposed to be drought loving, like many of our plants, and we have conversely been told to hold back on the watering as too much can suffocate the root ball.

It's hard to know what to do here. I just moved here recently from so. cal after 25 years of massively successful gardening and landscaping there, so it's a learning experience for me!:)

Oh, and my husband, who has lived here for 30 years, thinks that shooting the plants with water every night after the sun sets helps them "cool down." Huh?

Please advise.


    Bookmark   July 7, 2008 at 12:48PM
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Oh, and does the time the water comes on matter too much? I have always let my drips and sprinklers come on early, and here. I have the drips here start at 4:00 a.m. (I had them set at 5:00 a.m. but then it started heating up so early, I thought it better to push it back.) Too early?


    Bookmark   July 7, 2008 at 12:52PM
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Thoses adjustable emitters can put out 10 gallons per hour when fully open. I've found if you try to close them down to one or two gallons they clog pretty easily.

Seven gallons sounds fine. Consider that one gallon of water will moisten about one cubic foot of soil. If your plants were five gallon size when planted you not only need to moisten the rootball, but surrounding soil as well. That encourages the roots to explore the native soil and establish the plant. The longer you can keep moisture in the root zone, the less often you will need to water. Plus our soils and water are salty. By watering deeply you push the salts down away from tender roots. Salt buildup is lethal to plants.

Hardenbergia are drought tolerant, but that's only after they have become established. The rule of thumb is 2 - 3 years for shrubs and 3 - 5 years for trees to become established.

Yes, gardening here is like nowhere else. Our clay soils hold lots of water which can be good, but if they stay wet and soggy they can suffocate roots. It doesn't really do much good to sprinkle plants once a day, but if you're going to do it, evening is the best time. In the middle of the day the drops act like mini-magnifying glasses and can burn leaves. Keep in mind that some plants can't tolerate salt on their leaves (like roses and citrus), which is what the water leaves when it evaporates. It's better to use your drip system to water early in the morning as you've been doing or at night. I like the early morning because I can see the 'geysers' or leaks easier.

What city do you live in? Most of the valley city's water conservation offices offer FREE landscaping classes to residents. Other great resources are the U of A Master Gardeners (602-470-8086 x 301), or the Desert Botanical Garden.

A great book I'd recommend is Desert Landscaping for Beginners from Master Gardener Press (we're all beginners when moving to the desert). It has chapters on watering, citrus, roses, lawns, pruning, cactus, landscaping for wildlife, etc. They also have Desert Gardening for Beginners.

I hope this helps.

certified arborist
certified landscape irrigation auditor
master gardener

Here is a link that might be useful: Books from Arizona Master Gardener Press

    Bookmark   July 8, 2008 at 12:19PM
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SALT BUILD UP!! That's it! I have noticed a ring of white sometimes after the initial water rings from the morning drip have dried, especially around the worst plant. Got to tell my husband about this.

And the point about deep watering the surrounding area to spread the roots makes great sense. I've got the drips set on a sort of medium low (I know that the output is high at full-open speed and we never use that one as it just creates a waterfall down our slopes). So, medium-low, 2 hours, with two days between waterings. Should help all the plants develop better roots, even the ones that are doing well, which is most of them.

I'll do all you say, and thank you for the book and classes tip, too.

You guys are the best!


    Bookmark   July 8, 2008 at 2:30PM
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