Should I thin out flowers to produce bigger lemons?

A: No thinning of the flowers. The first thinning is done when fruit is about the size of your thumbnail. The second fruit removal is done about four weeks later. Aim for about 30 percent to 40 percent fruit removal for mature citrus. In about four to eight weeks, you should know where the leaves will be — that’s important for removing sunburned fruit.

Remove misshaped, deformed, damaged, doubles or the smallest fruit during the first wave of thinning. On the second wave, remove possible sunburned fruit and leave fruit that is or will be shaded by leaves.

Fruit sunburning on exposed sides (usually west and south sides) and the tips is common in the desert. There is usually no sunburning on the east and north sides. There is a maximum size (determined by genetics) that the fruit will reach, but it is possible to maximize size in a higher percentage of fruit.

Pinch the fruit between two fingers and gently twist it off. Pay close attention to the bottom of trees, as a higher percentage of small fruit is located there. Young trees have fewer leaves to photosynthesize and will be better off in the long term if they are allowed to focus on their growth. You can leave some fruit if you want a taste.

Q: I have a space that has a height limit of 10-12 feet. I want to plant some columnar trees that won’t grow too tall. I realize that Italian cypress would work but would have to be trimmed to limit their height. Are there others that might work in our Las Vegas climate? For example: Emerald Green Arborvitae, Sky Pencil Holly, or any others?

A: To get a truly evergreen hedge in this climate is tough. We may have winter cold that kills the leaves of many smaller trees, followed by leaf drop.

Tiny Towers (aka Monshel and Compacta) from Monrovia Nursery claims it to be only 10 feet tall and 2 feet wide and very slow growing. Monrovia claims it grows to 25 to 30 feet tall and 3 feet wide. Others confirm 20 to 25 feet at maturity.

What maturity means, as far as age of the plant, is not clear. I would guess that it grows at 1 foot per year if not watered more often and given fertilizer. Watch out for the flopping of new growth — that tells you are watering too often.

Monrovia said it was taken as a dwarf sport from an existing Italian cypress. Las Vegas USDA zone classification is 8A through 9B, so it is well within those hardiness zones.

Q: We had six 24-inch box bay laurel trees and one 24-inch olive tree planted in April 2021. We water once a week for one hour with four, two-gallon per hour emitters in the spring. We are not sure if they are doing well and would appreciate your expert advice.

A: If it were me, I would flood the area around the tree, a single time, with water now. Don’t wait. Use a $12 stationary sprinkler at the end of a hose and adjust the watering pattern from 6 to 8 feet. Water this way for one hour.

Next, I would increase the four emitters to 4 gallons per hour rather than 2. I would still water for one hour. As trees get bigger, they need more water. I believe you did not give these trees enough water when they needed an increase in water.

A normal response to a lack of water is leaf drop and thinning of the canopy. I doubt it is a disease problem. I would first guess it’s not getting enough water as temperatures increase. This is normally taken care of by increasing the number of times you water per week.

In your case, I think the 2 gallon emitters did not release enough water. Replacing the emitters is sometimes a better solution than increasing the water output for all of your plants. This way your watering time does not change.

Some people plant these trees in dry soil. Make sure they are planted wet. Watering now with a stationary sprinkler, wet all of the roots immediately. Make sure those 4 gallons per hour emitters are 6 to 12 inches from the trunk. All of the soil should be wet between irrigations. These are not desert trees, but water-loving mesic trees.

Q: I rooted these avocado pits in containers. Got great roots. Got stems and leaves. I planted them in good soil with organic stuff. And then they died. What did I do wrong? I have them under a plant light. Any suggestions?

A: At least two reasons could be involved: watering too often or not watering frequently enough, and not enough light. My first guess is watered too often. Not too much water but irrigation frequency.

I lift the pot to judge how wet the soil is before watering. After watering, the pot is heavier. Avocado should never be watered daily. At most, it should be watered every other day. Some plants like succulents might need watering once every two or three weeks in the winter, even in a container. In the summer once a week is usually enough. Always water until water comes out the bottom of the container. This is to keep salt in our irrigation water from increasing in the soil.

If the plant is watered too often, it will develop a disease problem that chokes the plant at the top of the soil. This is called collar rot. It will develop good, strong roots; it’s just that it is watered too frequently.

Frequency of watering depends on the size of the container and amount of soil. Smaller containers and small amounts of soil are watered more often (never daily) than larger containers and soil amounts.

Next is the issue of light. Is the plant outside during the day? Give it extra light during the winter by placing the light source extremely close to the plant. Florescent or LED lights are best and cooler than incandescent. Bring the plant in at night if temperatures threaten to freeze.

Bob Morris is a horticulture expert and professor emeritus of UNLV. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.