Citrus cuttings should not be planted upside down

Q: I’m hoping you can help answer how I can start a citrus tree from a cutting. Can citrus trees be started just from cuttings? I mean just a cutting without the rootstock since I don’t have the rootstock to graft it onto.

A: When you do that, it will be on its own roots. Cuttings will be about ¼ inch to ⅜ inch in diameter and about 6 to 8 inches long. The cuttings should be cut slanted at the bottom and straight across at the top end.

Cutting them slanted at the bottom end helps to not confuse the top from the bottom. These cuts should be about ¼ inch below the bottom bud and ¼ inch above the top bud.

Planting cuttings upside down will confuse the cuttings and they may not grow. Do not leave any part of the stem to dieback to the bottom or top bud.

Buy some powdered Rootone (such as Hormex No. 3) to ensure success. The cuttings should root on their own, but it is cheap insurance to use a rooting hormone. Watch a video on how to use the rooting powder.

The only thing I would add is to make the hole first with what propagators call a “dibble,” but you can use a pencil and then insert the cutting into it. Making the hole first helps, then closing it off by hand, prevents rubbing off the powdered rooting hormone.

Use a potting soil for the container or the propagating material. Put stem cuttings about 6 inches apart with at least two buds below the soil. Start twice as many stem cuttings as you need because they all won’t root. When new growth occurs, you will have new roots on the cuttings and about two weeks after that they can be transferred into the garden area.

Q: I was reading your book on suggested trees for Southern Nevada, and I saw a few oaks mentioned. I am thinking of using Quercus fusiformis for shade in a parking lot or parking area in Phoenix. Do you have any thoughts?

A: There is a lot of confusion right now about this tree. It is sometimes in the nursery trade as southern live oak (Q. virginiana) and sometimes as Q. fusiformis, and sometimes named Q. virginiana var. fusiformis. The scientists will figure it out.

Texas live oak (Q. fusiformis) is not generally recommended as a parking lot or street tree for the hot Sonoran Desert surrounding Phoenix. I realize Phoenix is hotter than Las Vegas (Clark County) but I think Dr. Chris Martin at Arizona State University does a good job pointing out the problem between Q. virginiana and Q. fusiformis regarding parking lots and used as a street tree. It is generally too hot in the summer for it. If used in a parking lot, I would be very careful and provide plenty of grow room for the roots and water it when stressed.

Q: I need to replace my raised beds this year. The old ones are made from cedar and have lasted 10-12 years. I am considering switching to pressure-treated due to the cost difference. My question is that OK for my vegetables? I am told that the chemicals used today are not a real health risk. Any thoughts or comment would be helpful.

A: The best wood for making raised beds naturally, without human-made preservatives, are redwood and cedar. The fastest decaying woods are pines.

Ask your provider which preservatives are used in your wood. The older chemicals used combinations of arsenic, chromium, creosote and pentachlorophenol. The older chemicals killed everything including humans if the concentration was strong enough.

My understanding is that the chemicals used to treat lumber now are not as much of a health problem as the older ones, but they can still be a health problem. The typical lumber preservatives used now in the homeowner lumber industry are: alkaline copper quatenary (ACQ), borates, copper azole, copper naphthenate, copper-HDO (Bis-(Ncyclohexyldiazeniumdioxy) and polymeric betaine

You can see they are still chemicals but chemicals which don’t pose as much of a health problem (we are told) for humans as the older chemicals. You can’t get away from chemicals, but you can pick chemicals that are safer to use around humans.

Check www.epa.gov/ingredients-used-pesticide-products/overview-wood-preservative-chemicals.

Raised beds that are 10 years old before replacement is a good age. I would still use redwood or cedar instead of preservatives. Be responsible and limit what you can while you still have the chance.

Q: I have a star jasmine and it froze last winter. What can I do to get it back?

A: Where are you located? It doesn’t freeze until it gets winter temperatures around 5 degrees F (USDA plant hardiness Zone 7) or perhaps a little bit colder. I would suggest that your winter temperatures may not be warm enough and you might be in the wrong USDA hardiness zone for this plant. In Las Vegas, we are in USDA zones 8b through 9a (Sunset zone 11).

If the top froze to the ground, you might be able to grow it as an herbaceous perennial, which means it might come back from the roots or crown after the top freezes to the ground. Some winter tender plants will do that. It just depends on the plant.

One of our plants that will come back after mild winter freezing temperatures is bougainvillea. Apply a layer of wood chip mulch to keep the roots or crown from freezing and apply water and fertilizer when it starts to grow again.

When winter temperatures approach freezing temperatures surround the plant with wood chips. I use a 1- or 5-gallon plastic container filled with wood chips to protect the plant from winter cold until the warmer temperatures of spring arrive.

Q: I have a parking area that never gets any shade. I want to plant something there that would shade the car. Can you suggest a tree for that spot?

A: Trees use water. Larger trees use more water. With our water crisis and plant water use, I would avoid planting trees. Instead, I would construct a shade structure. Shade structures don’t use any water but will require regular maintenance instead.

Materials that require less maintenance are made from cement and aluminum or steel. If you want to decorate it with plants, use vines instead. Vines planted at the corners and allowed to grow along the top will require less water than a tree.

Q: I planted some fruit trees in Searchlight at about 3,500 feet of elevation. Although large, my plum tree produces sick-looking fruit that is not edible. Is there anything I can spray or treat the tree with to improve the fruit or do I have to start over?

A: It sounds like you have a bad variety of plum. No, there is nothing you can spray or use on the fruit tree to improve the fruit. The fruit will stay the same regardless of the fertilizer or sprays you use. Unfortunately, you must start over.

All plums will not work in the desert. The variety you select is very important. If you are dead set on plums then I would suggest you decide on whether you like hard or soft fruit. Although many will work, of the soft fruited varieties, buy Santa Rosa, Catalina, Burgundy and Burbank which are purple or dark red. I have found them to produce good fruit in the desert.

Don’t forget pluots. Pluots are hybrids of plum and apricot but produce fruit that looks like plums. Of the red pluot varieties that have performed well and are productive, try Flavor King, Dapple Dandy and Flavor Grenade.

This is a good climate for plums or pluots, but avoid hot locations. All of them need to be thinned for larger fruit. They grow best on eastern or northern exposures, 8 to 10 feet apart, unless grown in the shade of other trees like in an orchard. Plant them in amended soil and cover the soil with wood chips. Any of the semi-dwarfing rootstocks work well.

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.