Bitter Orange a Good Choice for Las Vegas But....

Q. Is it possible to grow sour or bitter orange in Vegas? It’s becoming almost impossible to find at the local markets and we use it in so many recipes. I was curious if that was something that might grow here? When should I plant it?

Bitter orange, sometimes called trifoliate orange, is a good choice for colder climates like Las Vegas where it oftentimes freezes.

A. They aren’t very popular here. I understand why you might want to grow them. We are talking about Citrus aurentium. They are used as a landscape highway plant or landscape hedge in the Phoenix area where it’s warmer during the winter. Here they are mostly used as a low temperature rootstock for citrus when shipped to our area by wholesale nurseries. Trifoliate orange is used primarily as a freeze tolerant rootstock for our area, but sour orange is also used.

Sour orange is used as a rootstock for citrus needing to be cold hardy. If the top of a citrus dies due to freezing temperatures, at least the rootstock will sprout and grow after the top freezes.

I don't have the information on their low temperature tolerance for the winter, but I think it’s around 20° F so it would be a good choice for planting in the Las Vegas area. Meyer lemon and kumquat, two more commonly grown citrus here, will handle freezing temperatures to about 24-25° F. once established. In protected backyards Meyer lemon, grapefruit, and kumquat survive most of our winters. So, my guess a fifteen-foot sour orange will be at least reach those temperatures, if not a bit lower.

This tree should start flowering in about year four to six. You will still lose fruit due to early spring freezes combined with open flowers in some landscapes depending on its exposure to early spring freezes and wind. But the tree itself should survive our annual fluctuating freezing temperatures for about 25 years or more.

Remember ALL citrus are from China and parts of southeast Asia. This means the desert soil needs to be amended at the time of planting, and periodically adding amendments to the soil. No citrus are xeric so they will need about the same amount of water as regular fruit trees of a similar size, about 4 to five feet of water under applied under its canopy in one year.

Just for your information bitter orange does get a deadly disease occasionally but it's usually not prevalent in non-orchard citrus areas so you should be all right. Buy the tree smaller and protect the tree from sun damage through shading itself or providing it shade while it gets established. Buy a tree that is shrublike.

You won’t find it locally. It is not that popular as a tree on its own. I think you will have to order it online. Places outside of the desert southwest don’t have to worry much about sun damage to the trunk so it is limbed up higher into a tree. For this reason, you want to buy it grown into as much of a bush as possible. Limb it up later when it gets older and acclimated to our desert. The best places to order it are from Arizona nurseries such as Whitfill or Greenfield if they will ship it to you. Both are in the Phoenix area.

Plant it when temperatures are cool, but spring planting is best in the case of citrus. Because of digging and availability, most nurseries sell bareroot trees in the spring. Bareroot trees need to be planted as early in the spring as possible. Potted or container trees can be bought anytime but planting them is always best in the spring. If it were totally freeze tolerant, or you were sure it will not get extremely cold this winter and you can find it available, then fall planting is always best.

Why Not Encourage Winter Planting in the Warm Desert?

Q. Why do you encourage people to avoid planting during the winter months? I can understand it in Minnesota but why southern Nevada?

Oleander winter freeze damage during a particularly cold winter.

A. Simply because I don’t know what is going to happen. I tell you spring and fall are the best times to plant. If it is a warm winter. then planting during the winter is okay. But if it is a cold winter, such as the lower teens at night, then be careful! Plants need soil at least at 45 -50F to grow roots. Otherwise the roots just sit there until the soil warms. 

Winter Freeze?

Cold or freeze damage to myoporum (locally known as Australian racer).

Will it freeze this winter or not? If the plant is winter tender, like bougainvillea or most citrus, then you are playing Russian roulette with the winter temperatures. It is best to plant those (that might freeze during the winter) in the spring for that reason.

Winter freeze damage to bougainvillea.

Grape Vine Killed by Winter Cold

Q. I planted two vines in my backyard  3 year ago and it sprouted and grew very quickly but as you can see this year it has not done anything with the exception of the few countable leaves and the three new shoots.  I do notice some holes in the few leaves.  I live in Montreal Canada.

 

A. You are a little bit out of my climate zone but I'm going to take a stab at it. I am guessing, from the looks of it, it had some winter cold damage. There is a difference in cold tolerance among grapes. Those with some vinifera genetics in them (most of the European wine grapes are vinifera types) are less cold hardy than some of the American hybrids.

For instance Thompson seedless grape has vinifera in it and is less cold hardy than Concord, an American grape. I don't know where you got your particular grape and whether it was grafted onto a rootstock or not but if it was grown on its own roots than any suckers which could grow from it could be used to replace the dead vine.

Suckers growing from it should be extremely vigorous because of the already larger root system. It could be back up on top easily this growing season if you remove all but the strongest sucker. As it grows longer, tie it to the post. Strip all of the leaves and shoots off of this sucker until it finally gets on top. This way it will grow faster and you will direct the growth.

Give it a little extra water and nitrogen fertilizer and it will grow faster when the temperatures are warm. That's my best guess at it given the information I have and pictures. I saw one strong shoot coming from close to the ground in one of your pictures. You would cut it just above the strongest growth to reestablish it.

Protect Citrus From Freezing Temperatures Soon

Q. When should I begin to protect plants like citrus from the freezing weather that’s coming?

A. Some citrus will handle the cold weather better than others. Most of the citrus sold in this area are grafted to a cold hardy root system called a rootstock. Damage or even death results when the temperatures remain low enough to kill the top of the tree, its root system or both.

This citrus died from winter freezing temperatures several years ago and the sour orange rootstock grew in its place producing oranges that were too sour to eat.

            The more cold hardy and reliable citrus here are kumquat, grapefruit and Myers lemon. However, they will not survive the cold if the roots which they are grafted to are not cold tolerant as well. Most plants sold by nurseries in this area have citrus on cold hardy rootstock. This might not be the case if you buy citrus online.

Spring freezing weather caused this fig to die back and push new growth from lateral buds along the stem.

            None of the citrus are severely damaged if temperatures remain above 32° F. The least cold tolerant of the citrus, such as limes, is damaged when temperatures drop below freezing. When temperatures are low enough to damage the top of the tree but not the rootstock, suckers or water sprouts grow from the rootstock the following spring while the top of the tree may be dead or severely damaged.

Freeze damage to bougainvillea

            As we start getting close to 32F, start watching the local weather reports or track the low temperatures online. When you see projected temperatures reaching 32° F or lower, wrap the base of the tree with a blanket or cover this area with mulch. Smaller trees or trees pruned into an espalier may be entirely covered with a blanket.

            Some people wrap tender trees with Christmas lights on a timer that comes on at night. This may work if temperatures are not extremely low and there is no wind. Blankets should be removed the next day when temperatures climb above freezing.

When to Cover Winter Tender Plants in the Mojave Desert

Q. When should we cover Pygmy Palm, Bougainvillea and other plants that will freeze here in Henderson?  I have burlap to cover them.

Bougainvillea freeze damage

A. Both of these plants can tolerate temperatures to near freezing and they don't seem to have problems at temperatures below 45° F that causes chilling damage to some plants. Some tropical plants such as tomatoes may show chilling damage to fruit at temperatures below 45° F. This is why it is best to not refrigerate tomato fruits.

            It seldom freezes in the Las Vegas Valley before Thanksgiving. After Thanksgiving you might expect freezing temperatures at the higher elevations such as in Summerlin or in very low spots in the Valley where cold air collects. In Henderson, this might be in the old Pittman area or along the wash.

            Cold air, being heavier than warm air, settles into low geographic areas. Cold air tends not to settle on gently sloping land or hills.

            Freezing temperatures are more frequent where plants are exposed to wind. Plants growing along major streets tend to freeze more often than those in protected backyards. Major streets are urban canyons that channel cold wind in the winter. Backyards are more nestled away from these exposed urban canyons.

Sehgal palm cold damage

            Plants growing close to brick or cement walls that face West or South are less likely to freeze than plants growing further away unless wind is involved. Brick and cement walls exposed to the sun store heat during the day and radiate this heat at night keeping the plants a few degrees warmer. If wind is involved, it removes this radiant warmth making these plants more susceptible to freezing temperatures.

            Bottom line, when the weather forecast is for freezing temperatures, cover the plants with an old sheet, blanket, or in your case burlap, before nightfall. Drape this covering over the soil or any surface that can radiate heat at night. Remove this covering the next morning after temperatures are above freezing.

            In open areas, expect freezing temperatures after Thanksgiving and up to March 1. In protected areas, expect these temperatures anytime between mid-December and mid-February but watch your local weather forecast closely and adapt this recommendation accordingly.

Assess Plant Cold Damage in the Spring and Fix It

Q. Are there are any plants I need to prune or trim down before the frost comes to the Las Vegas valley this year?  I noticed that oleander suffers greatly from frost, foxglove, asparagus ferns, potato vine and a purple flower trumpet flowered plant are kissed when the frost comes. Should these be covered also?

A. Damage from frost will be variable in different places throughout the Valley. There are places which are naturally cold spots and others in windy locations. These areas will be hit the hardest.

            Then we have the variability of the weather. It was not too long ago that we had unusually

Difference in cold damage between two different types of Oleander

warm winters where it hardly froze at all. Then we had a terribly brutal winter with the coldest temperatures hitting us in February when plants were just waking up from dormancy.

            Then we have variability in the plants themselves. As far as oleanders go, there are winter tender types and there are very cold tolerant types.

            My basic advice is to leave most ornamental plants alone. Wait until the coldest part of the winter has passed, or you begin to see the beginnings of new growth, and then remove what has been damaged. Oleander and asparagus fern can be pruned to within a few inches of the ground and they will recover.

Oleander will recover by summer if it is pruned to within a few inches of the ground. in late winter

            This doesn’t hold true with citrus. Citrus planted in cold locations will have to be protected if you want it to survive or you want fruit.

Bamboo Can Be Cut Back to Repair Winter Damage

Q. I have bamboo that was damaged last winter as you can see from my pictures. New growth is emerging from them but they are still yellow and brown. Should I fertilize them or give them iron?

Lantana and Yellow Bells Should Not Be Dead from Winter Cold

Q. I have had Tecoma stans, Yellow bells, in the backyard as well as lantana for the past 3 or 4 summers. They do well but never winter over. When I dig them up to replant, the root structures seem to be healthy and alive. The tag on the plant says they are cold hardy. Is there anything I can do to help them winter over?

Repairing Lemon Trees From Winter Cold Damage

Q. Our lemon tree shows damage after our recent very cold spell.  Some of the leaves are dry and dropping.  Is there anything we can do to assist the tree?

Sago Palms Damaged in December

Q. Do white fronds indicate my sago palm has frost damage? Can my sago be saved? Should sagos be wrapped and, if so, do I just cover them when the temperatures drop down to the 20's but then remove the wraps once the weather warms up?

Freeze Damage on Acacia Can Be Hard to Fix

Q. Any advice on Acacia trees would be great.  These trees took a hit when the temps dropped to the 20's in December.  I see new growth, but mostly on the suckers.  Should I leave the suckers there or remove them? What is the best thing to do to help these trees recover?
 

A. This is more complicated. First you will remove any wood you know is dead. By now (June), any part of the tree which is still alive should have thrown out some growth. Remove any limbs that are dead (no growth coming from them) by cutting at point of attachment to another limb or the trunk.  You should not leave any stubs when you are done.

            If the limb is large and heavy, you should remove it by either removing sections of the limb at a time that are manageable or use a technique that we sometimes call the 1-2-3 method. This is demonstrated pretty good on Wikihow http://www.wikihow.com/Cut-a-Limb-from-a-Tree

            Next, remove any broken branches. They will not repair themselves. Remove any wild or “sucker” growth. This type of growth usually has weak attachment to the trunk and not support itself in years to come. Remove any growth coming from the trunk that is not high enough in the future.

            This growth will not get any higher and as it gets bigger will “sag” or bend downward perhaps into places where you can bang your head. Remove these by making a “flesh cut” in other words remove it all and don’t leave a stub.

            Finally thin out the remaining branches so that any dead wood is removed (again by making “thinning cut” which is the same as in the third sentence, removing it at a point of attachment without leaving a stub.) Try to have the remaining branches going in different directions to help balance the crown visually.

            I hope this helps. By the way, I would do any major limb removal next early spring after the worst temperatures have passed. Minor cuts (with a hand shears) can be done any time.

Using Ficus as a Hedge/Screen Around a Pool in Phoenix

You scared me for a minute. I'm in Las Vegas so when I saw your Ficus mentioned I was concerned. I am less concerned with it in the Phoenix area but the pool area puts it in a different twist and you still have to worry about freezing damage.

            But I am going to copy this to my good friend Terry Mikel who was your Extension Specialist in Maricopa County with the main office in Phoenix. He is better at answering this one and I will post his answer. He is in retirement but I am SURE he will come out of hiding on this one!

Q. I live in Glendale Arizona. I have a 45ft section of 6 foot brick wall that I would like to plant Ficus nitida along. There is a 4 foot width between the wall and a plaster underground swimming pool. No problem watering the hedge?  But will this plant seek the pool water and cause a problem. I am not worried about frost. I want a 10 foot hedge when done.

A. Your thoughts about having a hedge sound good.  Ficus microcarpa sub species/or cultivar 'Nitida' can fit the situation; its clean (no real messes). evergreen and makes a dense wall of foliage.

            I have to use the term 'can' with a couple caveats. 

1. This plant can grow to a very large size.  Frosts every few years help keep them in check.  And pruning can, to a certain degree keep them in check.  But, frosts and pruning will be a continuous battle against their genetics: it wants to be a 60' tall and 80' wide tree.

2. This species of Ficus will after time develop huge surface roots that will lift, push or barge anything in their path.  It’s their genetics and watering will have little, if any affect so the wall to the one side and any pool decking on the other side will be vulnerable to the large lifting roots.

            Your one concern about them 'seeking' water is a commonly misunderstood trait of any plant. . . Plants do not search out water, period.  Plants send out roots randomly in all directions and roots that run into a water source will proliferate.

            Pool sides, if sound will be the same a rock in nature, the roots will try to grow up, under, or around any solid object.

            If, and this is a big if there is the slightest oozing leak from the pool's wall  and a root meanders there then it will grow and proliferate in response.  That's where the issue of roots and pools becomes a problem.

            Personally, the Ficus is overused and most people who grow them quickly tire of all the problems with them.  If anyone who knew much about them would warn folks against using them except for large evergreen tree.

            Your setting is a little bit of a challenge. You might think about something much less vigorous with fewer potential problems and some have blooms (a potential 'mess' issue). Look at: citrus, Hop Seed Bush (Dodonea), Xylosma (both common and botanical name), Arizona Rosewood (or any in that genus of Vauquelinia), one of the many different blooming colors of Arizona Yellow Bells (Tecoma and various species and varieties), Petite Oleanders have been used in that setting for generations.

            Every person's 'likes' and 'dislikes' vary. Check with your water department and pick up some of the nice booklets about planning and plants for the landscape. These were produced by the Arizona Municipal Water Users' Association, more lovingly called AMWUA to be distributed in the different communities.

            Another resource might be going to the Mountain States Wholesale Nursery (MSWN.com) site for a truly complete list of plants that are well adapted in the lower Sonoran desert. They also produce some for the higher deserts but their main goal is for lower deserts. .

Respectfully,

Terry H. Mikel

When Should I Cut My Grape Vines Back?

Q. When should I cut my grape vines back?  They're on a trellis, and are 1 year old.  During the summer they spread out very well, and produced several large groups of table grapes.

A. I would wait until late February or early March to prune them. We still have some potentially difficult times to go through this winter for grapes. Cutting them early may result in a loss of bud wood and fruit production.

            When pruning you will cut back this past years growth (it will be a different color) so that only one or two buds remain. I prefer two. Also I usually prune it back so that ten or twelve buds remain if I do it early. Then just before bud swelling in the spring (like about early March) I cut then spurs back to two buds. This way if there is dieback during the winter I won't lose the fruit producing spur.

Yellowing in Palms Can Be Lots of Different Things

This is California fan palm with cold damage from
temperatures in the low 20's or high teens F

Q. We have a fan palm where the palms are turning yellow and I'm assuming dying. One or two would be acceptable but we are have 5 and 6 that are going bad.

A. Let's cover some ideas about why your palms could have yellow fronds. These are the main reasons: older fronds are dying from natural causes and should be removed; fronds were damaged during winter freezes; too much water applied too often or too little water; palms planted too deeply; palms planted in heavy soil that doesn't drain well; palms planted with pure sand around the rootball; fertilizer problems such as iron, manganese or zinc.

Not totally sure on this one but it was probably
light cold damage on this date palm during the
 winter in low 20's

Palms should be planted with the soil taken from the hole plus 50% compost and a starter fertilizer high in phosphorus added. Palms should NOT be planted with their root ball surrounded by pure sand in the planting hole which is commonly done in Las Vegas. The idea of doing that is absolutely crazy.

Palms are high water users even though they tolerate high temperatures and our desert climate. Different types of palms require different amounts of water. The larger the palm, the more water it will require. Some of the highest water users will be date palm with their huge canopy spread. The amount of water will vary but most fan palms would be happy receiving about 20 gallons every time they are irrigated.

This is Queen palm, not a good palm for the hot desert
and probably lack of soil preparation or watering too often
or both

One of the common problems is irrigating palm trees with small amounts of water, like ten or fifteen minutes of drip irrigation, daily or even twice a day. Watering like this can fill the soil with water and suffocate the roots causing them to rot, diseased or both. So if you are irrigating your palms daily, don't do that anymore!

During the heat of the summer they can be irrigated two or three times a week, using 20 gallons each time you irrigate but the soil must freely drain the water away from the tree. In the wintertime you might be dropping your irrigation to 20 gallons every 10 days or perhaps even as long as two weeks.

Sometimes the soil lacks certain types of minerals that palm trees need. Deficiencies like iron and manganese usually appears as a discoloration in the fronds at the center the canopy, the most recent growth. This can range from light green to nearly yellow. If these inner fronds are yellowing then we can usually narrow this to watering too often, poor drainage or a lack of minor elements such as iron.

Center fronds, youngest, demonstrating yellow growth
which could be due to watering issues, soil issues
or possibly disease

Next February when you make your annual application of fertilizer use a complete fertilizer such as a Miracle Gro, Rapid Gro, or Peters. You can also use fertilizer stakes. Make sure it is well balanced and try to select a fertilizer with the three numbers the same or close to the same value like a 16-16-16 or 10-10-10. Add an iron chelate that contains the EDDHA chelate in the ingredients. Let's see if that works along with irrigating with a large volume of water but doing it less often.

Cold damage on palms usually results in the older fronds turning a bronze color first and then browning later as they die. General rule of thumb is if more than half of the frond has turned brown, remove it. The new fronds at the center of the palm should be healthy and green when they emerge in mid-spring.

If your soil is heavy and holds water a long time then plant on a mound 2 to 3 feet high and 6 to 8 feet across so the water drains away from the roots.

Prune Palms in Early Spring to Remove Winter Damage



Freeze Damage to Palm

Early Spring is a great time to be pruning your palms if they had winter damage. They are pushing new growth now so any pruning done now will be replaced with new growth over the next month.