weather icon Clear

Pruning can be done any time of year

Q: Is it too late to prune? We have artificial turf around the tree, but the borders are open for applying fertilizer. Is this good, or should we use fertilizer stakes too?

A: My old college professor used to say, “The best time to prune is when the pruning shears are sharp.” There is a lot of truth to that saying.

Pruning does not have to be restricted to winter months. If there is a problem, then fix it when you see. Prune with a hand pruner 12 months of the year. Reserve tools, such as loppers, hand saws and chainsaws, for the winter months or dormant season.

The biggest danger in our desert climate is removing too much just before the heat of the summer. There is a delicate balance between leaving enough new growth for shading limbs and leaving too much, which can interfere with fruit production.

There is a pruning technique called “summer pruning” used to help keep trees smaller and redirect growth where it is needed. The term “summer pruning” is a misnomer because it’s not done during summer but during late spring just after new growth has begun to surge. In our climate, summer pruning is in late March, April and up until early May depending on tree growth.

To me, fertilizer is fertilizer. If you haven’t applied any yet, then do so now. It’s not too late. The issue I have is whether there is enough soil exposed under the tree. The bare area under the tree not covered with anything but mulch should be at least half of the diameter of the canopy. For instance, if the canopy is 10 feet in diameter, then the exposed or open area should be at least 2½ feet on either side of the trunk.

There is nothing wrong with fertilizer stakes. They are convenient and less messy than a bag of fertilizer. But they are more expensive per pound of fertilizer than buying it in a bag. If you choose to go this route, then follow the directions provided by the manufacturer.

Q: This is our second year growing tomatoes from seed. We are having similar issues as last year. Some of the older leaves are yellowing and then dying. We are fertilizing once a week with a liquid fertilizer. We take the plants outside for an hour to accustom them to natural light. We have had issues in the past with spider mites, but I doubt that is the problem in their short lifespan.

A: When growing tomatoes from seed in the spring, the usual failures are associated with cold soils. When soils are too cold, tomato seeds either won’t germinate, germinate very slowly or the seedlings turn yellow and frequently die. The soils must be warm for strong and simultaneous seed germination and strong plant growth.

It is too cold now for spider mite problems. Spider mites become a problem during hot weather and dusty situations. It’s a good idea to take plants outside to acclimate but leave them outside all day and bring them in only when temperatures are expected to drop below 45 F. Use hot caps if they are planted in weather that is still cold.

When I first germinated my own tomatoes from seed in the 1970s, I would put seedling trays on top of the refrigerator or television for good germination. The seeds germinate quickly, and I immediately put them under strong fluorescent lights.

Now, I always use heat mats to germinate warm season crops like tomatoes. They make a huge difference.

When seedlings are grown in cold soils, there is the ever-present danger of plant diseases in the soil attacking plant parts below soil because the plants are growing poorly. These soil-borne diseases also cause yellowing of plant leaves. But this yellowing symptom results from soil problems. The temptation is to water more often but, actually, this makes the situation worse.

Again, warm soils get around these problems. Plants such as tomatoes can tolerate cool air temperatures and even thrive in them if the soil is warm.

Another cause of yellowing is a lack of fertilizer, in particular nitrogen. Classic lack of nitrogen causes old leaves to become yellow. Unfortunately, it can also look like the yellowing that results from the soil diseases.

A lack of fertilizer can be dismissed quickly if spraying yellow leaves with liquid fertilizer causes them to “green up” in a day or two.

I think your problem is most likely from cold soils. Next spring, germinate seeds using a seedling heat mat. They can be bought from local nurseries and online stores that sell gardening supplies.

Q: What is the best way to get rid of powdery mildew on my euonymus plant leaves?

A: These are probably Japanese euonymus, which is notorious for powdery mildew when grown in shady spots. Control this disease on euonymus either with chemicals or without them. The best way is without using chemicals but requires more work initially.

Controlling powdery mildew without chemicals requires understanding the conditions which create the fungal disease in the first place. These conditions are high humidity, splashing water, shade and lack of air movement across the leaves. Applying chemicals circumvents the disease but doesn’t find a long-term solution to the problem.

Make sure plants are in a sunny location or else provide more sunlight to the plants. If they are not, consider moving them to a sunnier location. Young plants should move easily. Older plants may require replacement.

Water from sprinklers should not splash on the leaves. Adjust the sprinklers to prevent this. Use drip irrigation when possible.

These plants are nearly always pruned with hedge shears. This is a no-no unless planted in a hedge. Prune to create openings for air movement through the plant and across the leaves to dry them more quickly after they get wet.

As a last resort, use fungicides. Fungicides that are sold to control powdery mildew on roses should also work. Neem oil provides some control of powdery mildew.

Q: I picked up 10 acorns in Illinois that were on the ground. Will these acorns germinate and produce an oak tree? What are the chances this tree will survive our desert climate?

A: There are about 20 different kinds of oaks native to Illinois. Two of the more common oaks are northern red oak and white oak. Both are not native to the Southwest. They will grow here, but you will have trouble keeping them healthy as they get older.

We have native oaks in the Southwest. There also are oaks available from nurseries suitable to desert climates. In the long run, you are better off planting those than growing your own from Illinois.

But I also understand the fun of trying. If you go down this road, be prepared that you may have to remove them when they are no longer healthy.

If you found acorns on the ground, then most likely the seed inside the acorn is mature. However, the seed may not be “alive.” Put the acorns in a bowl of water. Use the ones that sink and discard the ones that float. The floaters are not alive.

If you pick these acorns up in the spring, plant them in the soil. If you pick them up in the fall, simulate a cold winter by putting the “sinkers” in a plastic bag along with a moist sponge for three months. Then plant them in soil. It doesn’t hurt to leave them in the fridge longer if the timing is off.

In early spring, plant one to four of them in a 5-gallon plastic container with good water drainage. Mix compost 50/50 with native soil and use soil mix for planting.

Plant the acorns on their side in this amended soil, about 1 inch deep, in mid-November. Water only when the container starts to feel light when you move or lift it.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.

Don't miss the big stories. Like us on Facebook.
Entertainment Videos
Heavier traffic expected from EDC festival attendees
Electric Daisy Carnival attendees began to vacate the Las Vegas Motor Speedway starting before 5 a.m., the majority heading south on Interstate 15.
What it's like to skip the lines and fly by helicopter to EDC
What it's like to skip the lines and fly by helicopter to EDC. (Janna Karel Las Vegas Review-Journal)
DJ Steve Aoki visits Las Vegas comic book store
DJ Steve Aoki visits Torpedo Comics in Las Vegas Friday, May 17, 2019, for a signing for his new comic book series "Neon Future." (K.M. Cannon/Las Vegas Review-Journal) @KMCannonPhoto
Las Vegas Smith & Wollensky opens at The Venetian
After 18 years, the Smith & Wollensky location on Las Vegas’ south Strip closed in 2017, to be re-born two years later with a rib-cutting — instead of a ribbon-cutting — in The Grand Canal Shoppes at The Venetian. (Heidi Knapp Rinella/Review-Journal)
Colin Cantwell, Creator Of Iconic Star Wars Ships Visits Vegas
Colin Cantwell, who created and designed such "Star Wars" ships as the X-Wing fighter, and Death Star, met fans at Rogue Toys in Las Vegas today. (Mat Luschek / Review-Journal)
Beauty & Essex in Las Vegas makes an EDC Wonder Wheel
In honor of the Electric Daisy Carnival, Beauty & Essex at The Cosmopolitan of Las Vegas makes its Wonder Wheel party-worthy. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Giada talks Vegas Uncork’d
Giada De Laurentiis talks during Aperitivo Hour, a Vegas Uncork'd event, at her Caesars Palace restaurant, Pronto, May 10, 2019. (Al Mancini/Las Vegas Review-Journal)
Scenes from Vegas Uncork’d 2019 on the Las Vegas Strip
The 13th edition of Vegas Uncork’d by Bon Appetit brought four days of food, wine, celebrity chefs and parties to town, May 9-12. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Three ingredients Gordon Ramsay can’t live without
Bon Appetit's Andy Baraghani interviews the "Hell's Kitchen" chef during a Vegas Uncork'd event at Caesars Palace, May 11, 2019. (Al Mancini/Las Vegas Review-Journal)
Vegas Uncork’d launches wiith bubbles and a blade
Dozens of chefs representing some of the Strip’s top restaurants gathered Thursday at The Cosmopolitan of Las Vegas to launch the 2019 edition of Vegas Uncork’d by Bon Appetit. (Al Mancini/Las Vegas Review-Journal)
Bunky the Clown at the clown convention
Bob "Bunky the Clown" Gretton talks about his life as a clown and the Clown Convention which was in Las Vegas at Texas Station this week. (Mat Luschek / Review-Journal)
Frying soft-shell crab at Lola’s in Las Vegas
At Lola’s: A Louisiana Kitchen in Las Vegas, soft-shell crab is breaded and fried and served either as an appetizer, po’boy or platter. Heidi Knapp Rinella/Review-Journal
The Stove in Henderson makes Pecan Pie Pancakes
At The Stove in Henderson, chef/partner Antonio Nunez stacks buttermilk pancakes with pecans and dulce de leche and tops them pie crust crumbs. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Vinnie Paul remembered at Count's Vamp'd
The late rocker's favorite table at one of his favorite clubs in Las Vegas. (Jason Bracelin/Las Vegas Review-Journal)
4DX movie experience at Red Rock
4DX movie experience during a demo reel at Red Rock. (Christopher Lawrence/Las Vegas Review-Journal)
What To Do On May The 4th
There are plenty of events going on May the 4th this year around Las Vegas. Celebrate Star Wars and Comic Book Day all at once. The Rogue Toys, the 501st, Rebel Legion and Millennium Fandom Bar are all hosting fun events to help celebrate your geek-dom. (Mat Luschek / Review-Journal)
Las Vegas Water Sports Introduces New Attraction At Lake Las Vegas
Las Vegas Water Sports will debut its new aqua park attraction at Lake Las Vegas Days this weekend. (Mat Luschek / Review-Journal)
Making the Space Invader at Greene St. Kitchen in Las Vegas
Lysa Huerta, pastry cook at Greene St. Kitchen at the Palms in Las Vegas, starts with angel food cake, Fruity Pebbles ice cream and strawberry sorbet to create a space creature engulfed in flashing lights and swirling mists. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Las Vegas Pools
The M, Park MGM and NoMad are just a few great pools in Las Vegas. (Mat Luschek/Las Vegas Review-Journal)
Jose Andres explains Iberico pork
(Al Mancini/Las Vega Review-Journal)
Inside Life is Beautiful
Craig Asher Nyman explains how Life is Beautiful festival is booked and talks about this year's line-up. (Jason Bracelin/Las Vegas Review-Journal)
Tattoo'd America Pops Up In Vegas
Tattoo'd America, a new pop-up attraction on the Linq Promenade, had their grand opening Friday. The attraction is dedicate to the culture of tattoos. (Mat Luschek / Review-Journal)
Jose Andres gets key to the Strip
Chef Jose Andres was presented with a Key to the Las Vegas Strip and a proclamation declaring April 26 Jose Andres Day in Clark County by County Commissioner Tick Segerblom on Friday. The ceremony took place at his restaurant Bazaar Meat in the SLS Las Vegas. (Al Mancini/Las Vegas Review-Journal)
Sadelle’s in Las Vegas makes a grilled cheese with an inverted bagel
Michael Vargas, executive sous chef at Sadelle’s at Bellagio in Las Vegas, inverts an everything bagel and grills it with Swiss, cheddar and Muenster cheeses to make the Inverted Bagel Grilled Cheese. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Learn how to make China Poblano's Salt Air Margarita
Learn how to make China Poblano's Salt Air Margarita (Janna Karel Las Vegas Review-Journal)
Tattoo'd America invites you to have fun and take pictures
Kassandra Lopez at Tattoo'd America invites you to have fun and take pictures. (Janna Karel/Las Vegas Review-Journal)
Prime rib is carved tableside at Lawry’s The Prime Rib in Las Vegas
Dave Simmons, executive chef of Lawry’s The Prime in Las Vegas, which plans special cuts for National Prime Rib Day, demonstrates the restaurant’s service from rolling tableside carving carts. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Making gluten-free pizza at Good Pie in Las Vegas
Good Pie owner/pizzaiola Vincent Rotolo makes his gluten-free pizza.
Rockabilly fans enjoy Las Vegas weather poolside
Viva Las Vegas Rockabilly Weekender runs Thursday, April 18th through Sunday, April 21st with a huge car show on Saturday featuring The Reverend Horton Heat, The Delta Bombers and The Coasters. (Michael Quine/Las Vegas Review-Journal)
Brownie sundae at VegeNation in Las Vegas is completely vegan
Donald Lemperle, chef/owner of VegeNation in Las Vegas and nearby Henderson, NV, makes his sundae with ice cream made with coconut and almond milks, a brownie made with coconut flour and oil and organic sugar and cacao, and fresh fruit. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Stay away from heirloom varieties of asparagus

Asparagus usually grows well here, but there are some differences among the varieties. Stay away from heirloom varieties such as Mary Washington because they don’t produce enough spears in any climate.

Spray grapevines to control pests

Grapeleaf skeletonizer and grape flea beetle were found in the orchard during the last couple of days. These two pests damage grape leaves but few other plants.

Removing dead fronds doesn’t affect health of sago

Q: The top ring of sago palmfronds died after I transplanted it but remain on the plant. I left this brown ring of fronds around the crown of the plant and it looks like new growth coming from the center is OK. Should I trim off the dead fronds without disturbing the crown or just let them fall off?

Yellow leaves not necessarily caused by fertilizer

Q: I see many times where you’ve said fruit trees only need feeding in the spring. However, without periodic applications of nitrogen, my 3-year-old peach tree leaves become yellow. Could there something going on I should investigate?

Waxleaf privet should have more than one drip emitter

Q: I purchased a few waxleaf privet plants in February. They were planted in my yard using drip irrigation with one drip emitter per plant for about one month now. I am starting to see some black markings and yellowing on the leaves. I also think there may be some root rot, but I am unsure.

Removing excess fruit allows remaining fruit to grow larger

If you have fruit trees, the next big tree management activity you are facing is fruit thinning or removing excessive amounts of fruit so that the remaining fruit gets larger. Peaches, nectarines, plums, apples and pears must have excessive fruit removed if you want larger fruit. Do this as soon as the fruit reaches the size of your thumbnail.

Proper pruning, thinning, irrigation increases fruit size

Q: Peaches from my dwarf peach tree were very small again last year. This is the third year the fruit developed into a small size. We fertilize them twice a year with vegetable spikes and our in-ground system fertilizer system has Dr. Benson’s Natural Mix added five times per year. Any suggestions?