Home Landscape with Magnolias and Rock

Q. We moved to Las Vegas four years ago and had a professional landscape our backyard. We now have eight magnolias as well peach trees throughout our backyard surrounded by large rock up against the trunks. This rock makes it difficult to fertilize the trees and pick the fruit. Our gardener told us the trees are not getting enough water. Should I pull the rocks away from the trunk of these trees and put wood mulch around their trunks?    

A. First off, both peach trees and magnolias will not like the rock laid on the surface of the soil and surrounding the trees. You will see them start to suffer from this practice in three to five years. Both prefer an “organic” mulch that can decompose into the soil and improve it. That means a four-inch-deep layer of woodchips.

            When buying peach trees, they should be on a semi-dwarfing rootstock such as Citation. If bought on this dwarfing rootstock, they can be planted about ten feet apart, pruned to keep them small, the soil enriched with a good quality compost at planting time and the soil covered with four inches of woodchips, not rock. So yes, pull the rock back about three feet from the trunk and lay down four inches of woodchips instead.

Young magnolia planted in fescue lawn in Las Vegas.

            Magnolias? Eight of them? Wow. I’m assuming you are talking about southern magnolia with its beautiful flowers. Even in Georgia, where they belong, one specimen tree is more than enough for a large yard. Magnolias growing in Georgia can get 75 feet tall with a similar spread! These trees are NOT meant for backyard, or front yard, landscapes (desert or no desert) unless you have a huge property and water is cheap.

            As these trees get older (if they do) they will become a nightmare to maintain and water. Get rid of them now before they get fully established. One tree is enough to satisfy your curiosity and you will probably remove it in less than ten years anyway.

            Let’s say you keep the rocks. Using large rocks around plants has both pluses and minuses. If they are large enough, fertilizer or compost can be flushed on to the surface of the soil by washing it through the rock with a stream of water from a hose. Large rocks are also great for keeping people out. But you are right. Large rock makes it difficult to harvest and prune fruit trees. In my opinion, rock larger than 3/8-inch diameter is difficult for walking safely.

Where to Get Good Vegetable Seed

Q. I have been looking for seeds for planting fall vegetables and herbs and not having much luck here in Vegas. Where should I start? 

A. Start with varieties that have done well here in the past. Dr. Wittwer’s Moapa Valley vegetable growing “Bible” is a good place to start. He mentions several older varieties that have performed well for him. I can forward a copy to you if you don’t have it.

            Slowly introduce new varieties that have no production history in the desert. Be careful. Not all varieties produce well in a desert climate. Consult online vegetable seed sources like Gurneys, Park Seed Company, Territorial Seed Company, Baker Creek Seed and Grow Organic. Specialty seed sources like Kitazawa Seed and Seeds from Italy provide some interesting and heirloom seed sources.

            Heirlooms don’t produce as much food as hybrids, but they are oftentimes “tastier” if you can get them to produce here. heirlooms are not as "finicky" as hybrids so they don't require as much fertilizer and care.

Sick Raywood Ash on a Cul-de-Sac

Q. We have four established Raywood ash trees on our small cul-de-sac. Three are doing fine but the one directly in front of my condo is not. Just over the last few weeks, several brown dying  branches have appeared. Our landscaper said all that needed to be done was to trim the branches and give it more water. What’s your thoughts?

A. Large dying branches in ash trees may be from a disease called ash decline. It can be from a lack of water but if the tree doesn’t look much better after three weeks when larger amounts of water are applied, then it is probably ash decline disease. There is no cure for ash decline and the tree should be replaced with a tree that is NOT an ash tree.  

Ash decline disease or drought. Water the area under the tree with a sprinkler for an hour once a week for three weeks and find out.

            Plant diseases don't happen all at once just like they don't happen all at once with diseases in humans or animals. The reason you see it on one tree is because it may be just beginning. Eventually if one tree has it, they will all get it whether that is in 10 years or 15 years, I don't know. Keep an eye on the others. Remove infected trees early.

Greening Up Brown Italian Cypress with Ironite?

Q. Does Ironite help Italian cypress if they are turning brown?

A. No. Ironite may help if the problem is an iron deficiency or the plants can't take up enough iron. Iron problems on plants turn yellow first before they turn brown and die. If the cause of the browning was from poor irrigation management and the soil staying too wet because of poor drainage, then Ironite will not do any good. The same is true for browning due to spider mites.

            By the way, Ironite only works if the soil is not too alkaline (pH above 7.6). Most of our desert soils are closer to 8.0 or higher. Mixing in lots of compost and adding water helps lower the soil pH close to the mid 7’s. But if the soil has been covered in rock for a few years then soil pH (alkalinity) will be close to 8 or above.

Grubs and Improved Landscapes Go Hand in Hand

Q. I have grubs in sections of my fescue lawn. They have been a problem in the past and they are again this summer. How do you prevent grubs from re-infesting a lawn each summer?

Grubs feeding and growing larger in the soil beneath a lawn. They will become "June bugs" in the summer.

A. Make sure the brown areas you see is damage due to grubs before you apply grub control products. Most brown spots on lawns during summer months are irrigation or disease related, not from grubs. Usually grub damage starts appearing early in the summer.

            Brown spots resulting from grub damage is probably the easiest to determine. In early summer, grab a handful of grass from the edge of a suspicious brown spot and lightly pull. If green grass is pulled up without roots on it, then your lawn probably has grubs. YouTube videos will show infested grass rolling back “like a carpet” but that’s only on sod forming grasses like Kentucky bluegrass. We have mostly tall fescue in our lawns which is a “bunch grass”. That makes identifying grub damage in our lawns different.

White grub larva just before it will become a "June beetle".

            If you are convinced that brown spots are due to grubs, then apply an insecticide for grub control to lawns in late spring. If you want to get a jump on controlling white grubs, apply the same insecticide to the lawn September through October.

Desert Horticulture Podcast: Why Mulch is Important for Desert Soil

Mulch is anything laid on the surface of the soil. Selecting the right mulch and using it can mean plant success or failure in the long run. Organic and inorganic mulch play different roles in landscapes. Rock mulch may or may not be the right thing to do with your landscape. Learn why on this episode of Desert Horticulture.

Part Time Vegetable Gardener Needed

 I am helping an employer find a part time vegetable and herb gardener in the downtown Las Vegas area. Flexible schedule, time and hours. Easy parking. Good with the public. 

Contact me if you want more information. 

Extremehort@aol.com 

Check Your Garden Planting Schedule

Q. This summer I had a terrific garden with lots of tomatoes, but my zucchini died by mid-summer, green beans were lush and beautiful but produced nothing, and just a couple of fruit from my cantaloupe but no watermelon. I’m not sure if the roots of my carrots and beets have gotten bigger but they sure have beautiful tops! I rototilled in a bag of manure, waited two weeks, and rototilled again.

Be careful when adding bagged steer manure to a garden area. It has not been composted and so is considered "raw". Let it "rot" in the garden. 

A. Several things may have gone wrong for you. In a longer email you said they were planted at the right time of year. I’m not so sure. When it’s hot you should have finished harvesting your beans, carrots, and beets a long time ago. You could be planting for a second crop of these just before cool weather arrives, but you shouldn’t be seeing tops now. These are cool season crops.

I don’t know where you got your planting schedule, but I am sending you one that I created for a local company. It’s adjusted for 1000, 2000, and 3000-foot elevations. It also tells you which vegetables you can plant from seed and those from transplants only. You still need to adjust it for your local weather microclimates but it’s correct otherwise. I will be happy to send you a copy by email and to anyone who wants one.

Zucchini and melons are warm season vegetables. It sounds like they were planted at the right time. You don’t mention the varieties of vegetables you planted. Maybe you chose the wrong variety. Selecting a good variety for the hot desert and planting cool season vegetables just before cool weather arrives, is a must for successful gardens.

I am also sending you a copy of a local vegetable guide that suggests some successful varieties that you can try first. Record what you try and when you plant it. Plant trusted varieties first and experiment with unknown varieties in small numbers.

Sounds like you rototilled steer manure into your garden area. Nothing wrong with that. Sounds like the two weeks that you waited before cultivating a second time worked for you. Steer manure is not a bad choice it just depends on where it came from, how it was processed and, taking these into consideration, your level of comfort using it. Make sure you wash all of your vegetables before eating them.

Controlling Grubs before They Become a Problem

 Q. My question today is, how to deal with white grubs in established landscape plants.  I have seen them in a few yards in Mesquite, NV this year.  Is it just a seasonal thing?  I just found 7 more yesterday in Mesquite on one property.   How do I get rid of any there now and how to prevent in future?  Are some plants more susceptible than others?  Some of the plants I found them in the dirt:  Eucalyptus just planted, texas mountain laurel, african sumac, and I think they got a bunch of myoporum, agave parryii, Santa Barbara Daisy.

A. I will tell you as much as I know about these grubs. They like to feed off of decaying organic material. I think sometimes they get confused between dead and dying organic matter and small roots of plants like Lantana and so you find them everywhere. 

I guess I just figure that wherever the soil is been enriched and there's healthy plants you're going to find these critters. They mature into June bugs, metallic green June beetles, rose chafer's and just about anything else in that particular family of bugs. 

They are fairly easy to kill with a soil drench of Sevin insecticide but the problem is which plants do you drench? All of them? The adults pupate around May or June so if you are going to treat plants with an insecticide then you're going to do it fairly early in the season or fall. It doesn't make much sense to put down an application close to may because the are adults are going to emerge and fly around and meet and be back in the soil by July or so. 

You can try spreading the bacteria that are supposed to kill them long term or the nematodes. These biological control insecticides may take a bit longer to get established in the soil or they may require you to treat every year. Read the label!

So if I were to get a jump on them you would probably be in fall. The question still remains which plants do you treat because they are going to all look healthy even if they have these guys feeding on the roots or not.  

Taking Over Your Landscape and Monthly Calendar

Q. I have taken over my desert landscape maintenance, formerly serviced by a company.  Can you please provide a general monthly schedule e.g. fertilizing, pruning, seasonal changes in watering etc.

A. When I consult with people on managing their landscapes at their homes I encourage them to pay a little extra and use certified arborists for pruning ornamental trees and large shrubs. They are good at that. Only highly skilled gardeners are good at pruning fruit trees, roses and other flowering shrubs. These people are hard to find.

“Blow and Go” maintenance companies should not be allowed to do any pruning on your property unless they can demonstrate that they know how to correctly prune your plants. Hedge shears are commonly used for pruning trees and shrubs, this makes them look all the same; gumdrops. Hedge shears should only be used to prune hedges. Many of these types of companies are good at pruning hedges but not other plants.

I sent you a month to month calendar of operations but it’s too long to include here so I will post a more extensive list on my blog (below). Watering is the most important management practice in the desert. I discuss how to water landscape plants on my blog and some tools that would help you determine when and how much to water but water should be applied so that it wets the soil under the entire canopy of the plant. The amount of water applied is determined by plant size; large trees, water 36 inches deep, medium sized trees 24 inches deep, small trees and large shrubs 18 inches deep.

Fertilizers for trees and shrubs are applied once a year in early spring and only when plants need it. Flowering plants are fertilized just before they flower and some, like roses, are also lightly fertilized three or four times per year.

January, pruning and fertilizing trees and shrubs and roses, fertilize the lawn, annual flowers, vegetables and herbs as needed usually once a month. Water trees and shrubs one to three weeks apart.

Apply iron fertilizers to the soil to plants that show signs of yellowing

Control weeds

Dormant oil application on deciduous trees

February, last chance for pruning and fertilizing trees and shrubs including iron applications to the soil.

Light pruning as needed

Control weeds

Water trees and shrubs once a week

March, fertilize lawn, roses

Light pruning as needed

Test irrigation, make sure irrigation system is working properly for the hot months

Last chance to control weeds before it gets hot

Water trees and shrubs once a week

April, control ants causing problems by applying an ant bait

Water trees and shrubs once or maybe twice a week.

May, fertilize lawn. Water trees and shrubs twice a week.

June, light pruning as needed. Water trees and shrubs twice and sometimes three times a week.

July, fertilize lawn at half rate of fertilizer. Water trees and shrubs three to four times a week.

August, light pruning as needed. Water trees and shrubs three to four times a week.

September, fertilize lawn at half rate if hot, full rate if cooler. Water trees and shrubs three times a week.

October, fertilizer applications to trees and shrubs if needed. Water trees and shrubs twice a week.

Control weeds now that it's gotten cooler

November, go on vacation. Water trees and shrubs twice a week.

December, major pruning of large branches, dormant oil applications on trees and shrubs after leaf drop. Water trees and shrubs every one or two weeks.

Kumquat Good Choice for Container Citrus

 

Q. Can we grow Kumquats in our area? Are they water intensive?

A. Kumquats are a good choice in citrus if you want a low maintenance container plant and had had poor luck with citrus in the past. They use the same amount of water as other small citrus trees. Their mature size determines their water use. Kumquats are frequently more cold hardy than other types of citrus and provide some edible fruit that can be eaten directly from the tree.

            During very cold winters it might be deciduous but generally consider the tree to be evergreen and range in height from 6 feet to 20 feet depending on which variety you choose, with a width equal to its height. Unlike Meyers lemon that flowers usually during our coldest spring weather, it flowers and produces fruit throughout the year.

When to Pick the Fruit

            Pick and eat the fruit when it’s bright orange because, unlike peaches and apricots but more like figs and grapes, it won’t get any sweeter after you’ve picked it. Since the peel is not bitter, just pop the whole fruit in your mouth and eat it. It does however get sweeter as the fruit gets brighter in its orange color.

            Kumquat is not a desert plant, so it appreciates a reprieve from intense sunlight in the afternoon. In other words, don’t plant it where it will be in full sun or in a hot part of the landscape and don’t cover the soil in rock. Because it produces fruit and flowers, it won’t like a lot of shade either. East or North facing microclimates out of the wind are usually best.

Which Kumquat to Get

            Three varieties of Kumquat are popular for home landscapes and containers; ‘Meiwa”, ‘Nagami’, and ‘Fukushu’ which is a bit less cold hardy than the other two. There are some seedless selections available so look for those.

Desert Horticulture Podcast: Successful Fall Vegetable Planting

 

Here are some things you can do to make your fall vegetable garden more successful in the desert.

Desert Horticulture Podcast: Avoid Planting Landscapes During the Heat.

 Landscapes are best planted during the early spring and early fall months. Sometimes they are planted when it's hot. Learn some of the problems that you will encounter when planting out of season and why. All This and More on This Episode of Desert Horticulture.