Compost ingredients must be balanced to produce heat

Q: I’m composting in plastic trash cans with holes. It’s taking a very long time to make compost, despite adding carbon to my grass clippings and kitchen waste. I water and turn it every few days. What am I doing wrong?

A: Compost ingredients are divided into two categories: “brown” ingredients that are loaded with carbon and “green” ingredients that have much more nitrogen in them. Typical brown ingredients might be things such as shredded paper, cardboard, sawdust and pulverized woodchips.

Typical green ingredients can be scraps of fruits and vegetables and green parts of plants, including leaves and soft stems. Brown and green ingredients must be in proper balance to achieve a ratio of carbon to nitrogen between 20:1 and 40:1.

Composting is controlled rotting of a mixture of these ingredients. Brown and green ingredients are finely shredded and mixed together. Some water is added, along with a small amount of soil or fresh compost, and the compost is turned, or aerated, when the center gets hot. If heat isn’t produced by a compost pile, then one of the necessary ingredients is missing or in short supply.

Ideally, microorganisms from soil or fresh compost feast on moist carbon and nitrogen found in the compost ingredients. Heat is produced, and the entire mixture rots in a few months if these rotting microorganisms also get air. Air is provided by turning this mixture periodically or injecting air into the pile.

Commercial composters turn large compost piles when temperatures are about 160 degrees F toward the center of the pile. These high temperatures are needed to destroy human and plant pathogens and weed seeds.

Small amounts of compost are more difficult to start than large piles because of our desert environment. In our desert environment, place small composters such as trash cans out of the wind and protect them from the sun.

Make sure microorganisms are in the mixture. Add a couple scoops of fresh compost or a pound of garden soil to this mixture. Add extra nitrogen such as high-nitrogen fertilizer or blood meal if you think too many brown ingredients are in the mixture.

Q: I have a 7-year-old Panamint nectarine that never produced fruit, even though it has flowered. My Katy apricot sets fruit every year. Is this because of the wrong chill hours? I am resigned that I will never taste a Panamint nectarine.

A: The fact your tree flowered and didn’t produce fruit is a critical piece of information. If your tree didn’t produce fruit, I would want to know if it flowered or not. If a fruit tree doesn’t flower, it’s one set of problems. If it flowers but doesn’t set fruit, then it’s a different set of problems.

It is thought the Panamint nectarine needs about 250 chilling hours (total winter hours below 45 degrees F) to be satisfied so it will flower normally the next spring. If your nectarine tree had lots of flowers, then I doubt it’s a lack of chilling hours.

The Panamint nectarine is self-fruitful, which means it does not need another tree to provide pollen for fruiting. It needs only bees (pollinators) present when it flowers. If there is a lack of pollinators, then the tree will usually have less fruit, even though it had lots of flowers.

Bees can only visit a certain number of flowers. When there are more bees, more flowers are visited. Pollinators improve the amount of fruit produced by a tree if there are plenty of flowers.

Late spring freezing temperatures can be a problem with fruit trees planted in locations prone to freezing temperatures after flowering. On top of that, some varieties of fruit trees have flowers and young fruit more sensitive to freezing temperatures than others.

This is true of many peaches and nectarines. One or 2 degrees during and shortly after bloom can mean the difference between a few fruits and lots of fruit.

The most critical time for loss of fruit due to late spring freezing temperatures is when the flower is open through the formation of new fruit. Tolerance to light freezing temperatures is greater before flowering and after the young fruit has had a chance to mature a little bit.

After that many years of no fruit, I would get rid of it. Plant a variety called Arctic Star, which seems to perform better through cold spring weather and, in my opinion, produces a better nectarine.

Q: How much water does oleander, lantana and honeysuckle need during summer months?

A: Whenever talking irrigation, two important considerations should be made: how much water to apply and how often to apply it. How often refers to which valve or station they are on. How much water refers to the minutes of operation of that station and the size and number of drip emitters around each plant.

Deeper rooted plants such as oleander should be watered less often (but with more water) than shallower rooted plants like lantana and honeysuckle. Ideally, oleander should be on a station (valve) that waters other trees and large shrubs not desert-adapted. The lantana and honeysuckle would be fine on the same valve.

Next is size. Larger plants should receive more water spread over a larger area than smaller plants. Some oleanders get quite large, while dwarf varieties would do fine with a smaller amount.

Larger oleanders should probably get somewhere around 15 gallons or so each time they are watered, and smaller, petite oleanders should probably get between 5 and 10 gallons. If using drip irrigation, the size of the drip emitters used (gallons per hour) depends on the minutes allocated for that station.

Lantana needs 1 to 2 gallons every time it’s watered. The honeysuckle probably needs 3 to 4. If watered the same number of minutes, double the number or size of the emitters used on the honeysuckle.

Q: We have a large Mexican fan palm in our courtyard that is now about 15 feet tall. About 5 to 6 feet from the tree is a Pebblestone plastic divider that is slightly raised. The Pebblestone representative said it is likely caused by root problems from the palm tree. A gardening company told me the palm tree roots are not likely the problem. Which is it?

A: Palms are a different type of plant altogether from ornamental trees. They are monocots, while most ornamental trees are dicots. The internal physiology and anatomy are very different between the two.

Palm trees grow differently and have roots that are very different from ornamental trees.

Basically, palm roots grow closer to the trunk, while ornamental tree roots can grow a distance horizontally twice their vertical height, if water is available.

Ornamental tree roots are larger in diameter closer to the trunk and smaller in diameter with more distance from the trunk. Palm tree roots don’t get bigger with length, as ornamental tree roots do. Palm tree roots don’t increase much in diameter their entire length.

This increase in diameter of ornamental tree roots is very powerful. Heaving of sidewalks, patios, driveways, foundations, and footers of walls is frequently caused by ornamental tree roots increasing in diameter if planted too close to them.

Water and where it is applied will also control where roots grow in desert soils. If you want plant roots to grow in a specific direction and not another, apply water to the soil where you want roots to grow.

I would not plant palms closer than 4 feet from anything that might be damaged. Apply water in the area where you want root growth. Do not apply it close to other areas where damage could result.

Installing root barriers to add more protection to these areas is another option.

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

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