Late spring freezes can have devastating effects on plants that would otherwise sail through these problems. Find out why and what you can do about it on this Desert Horticulture Podcast.

Q. I only have a small container for composting so I mix it twice a week on the ground and put it back in the container. It’s about 2 months old and I’m wondering if I can use this compost now for my plants? Composting is nothing more than getting stuff that you don’t use to rot. Remember, garbage in and garbage out. If you want a high quality compost use good quality waste. A. What you’re doing sounds like a lot of work! To judge if a compost is “finished” or not, look at its color, consistency and smell it. It should be rotten through and through, all the same color and have a good smell. Composting is controlled “rotting” of the ingredients. A finished compost should be the same color through and through, and the smell should be earthy and not like rotten eggs or ammonia.             I like to divide composting into 2 categories; “hot” composting and “cold” composting. Hot composting relies on developing high temperatures to “sterilize” the contents from human pathogens while cold composting doesn’t. They both rot the ingredients but hot composting is much faster than cold composting. Compost can be soaked in water to extract nutrients and good microorganisms that can prevent disease and improve the microbiology of the soil. This discoloration of the water is a good thing and called “leachate”.Sometimes it’s referred to as a “compost tea”.             Your compost size is small so it will probably never become “hot” compost. Whenever handling any compost, always wear gloves and wash your hands afterwards. Your composting will be slow. You can speeded up by making the ingredients of your compost as small as possible. Compost is a good thing around plants and here it’s added to wine grapes. Just keep compost away from the trunk of plants or it may damage it.             Compost is best used when it is mixed with the soil at the time of planting. Compost added to the top of the soil will improve the soil on the surface but not much below the surface. Because this surface soil is improved, roots will grow towards the surface in or near this composted area. Yes, you can apply it but I would cover the compost with a layer of woodchips if you can’t mix it into the soil.             Try a composting technique called “pit composting”. It’s much easier to do than what you are doing if you have an open space where you can dig a hole in the soil and let the ingredients rot inside the pit.

Q. I had new landscaping installed last June and had to guess the proper watering schedule for my plants. I really don’t know what I’m doing or why I’m doing it so I’m asking you to please suggest a proper watering schedule for my landscape during the four seasons of the year. Homeowners irrigation controller with the watering schedule released by the local water purveyor. Now you just have to learn how to operate the controller A. I suggest you follow the irrigation schedule sent by your local water purveyor. How the irrigation system was installed is anybody’s guess. Most landscapes have a mishmash of plants with varying root depths and watering needs so it’s difficult to give a blanket recommendation that fits everyone’s situation. Research like ours clearly shows water use of plants varies with the seasons. This shows monthly water use of plants in general starting in January (1) through December (12). The trick is figuring out how to apply this schedule with an irrigation controller.             You are already ahead of many people because you recognize your irrigation schedule should be adjusted seasonally. This adjustment to your watering schedule is primarily the number of days per week that you water. Once the number of minutes is established, or the amount of water plants receive, it doesn’t vary seasonally. The amount of water plants receive is adjusted by increasing or decreasing the number of drip emitters delivering water to each plant.             There are four seasons in our desert but for someone who uses snow to recognize that it’s winter, they will be lost here. People might argue this point but the four seasons we have start approximately in February with Spring, May for summer, October for Fall and December for Winter. These months are the approximate times when irrigation controllers are adjusted to more or fewer irrigation frequencies each week.             If you want more precision about how much water to apply, grab a three foot long piece of “skinny” rebar. If you push this rebar into the soil after an irrigation, it will slide into wet soil easily. A piece of rebar about 2 to 3 feet long helps you to estimate how deep water from your irrigation system has penetrated into the soil. This can easily be translated into how many minutes you should use on your irrigation controller for that valve.             Push it deeper until it’s hard to push any more. It’s difficult to push when it reaches dry soil. This is the depth of the irrigation water. Repeat this in 3 spots around the plant to get an average “wet soil depth” reading. If you hit rocks when you do this, keep poking the soil in different places until you find a place where you can push it in and get a measurement.             Small plants, approximately a foot tall, should be watered a foot deep. Medium-sized plants, up to about 8 feet tall should be watered 18 inches deep. Water small trees and large shrubs 24 inches deep. Large trees require deeper irrigations so water them about three feet deep. Adjust the amount of water these trees get individually by adding or subtracting emitters.

Q. I have a Mimosa tree that is about 15 – 20 years old with four main branches forming the trunk of the tree. These four branches form a “well” about 8 inches deep which catches rainwater and remains wet for about a week or so after a rain. Someone recommended filling this “well” with roofing tar so that the tree doesn’t rot at the point where the main branches come together. Not the readers picture but a silk tree that started to yellow. It could be poor drainage but it also could be the beginning of a disease called Mimosa wilt. A. Mimosa, or silk tree, is not a long-lived tree due to disease problems. At 15 – 20 years of age it’s getting close to the end of its life. Its short life is because of a disease problem called Mimosa wilt disease that invades some of the limbs and causes limb or stem dieback. The tree usually dies in a matter of months once it gets the disease.             The reason I’m mentioning this is because you should realize this tree may die regardless of what you do so prepare yourself for that eventuality. It may die because of nothing you did or didn’t do. You don’t see a lot of old silk trees around for a good reason.             I think filling that well with roofing tar is a bad idea and will damage the tree. Rainfall is so infrequent in our desert climate that I don’t think it’s worth the effort or concern. If this catchment is filling with water because of frequent irrigations by sprinklers, then this situation is different.             Secondly, any compound made from petroleum is potentially damaging to plants. Petroleum products are normally not applied to plants because of their toxicity. You run the risk of damaging parts of the trunk in contact with the roofing tar.             I appreciate the concern you have, but in my opinion if that tree has survived this long, then leave it alone.

            Another freeze went through the valley this past week along with some unusually cold weather. Freezing temperatures are more damaging to plants as we enter the spring months because plants are starting to “wake up” from their winter dormant period. These same plants might have no problems with these temperatures in December and January. Spring recovery of oleander from a freeze that did a small amount of damage             During these low temperatures, honeybees were not flying during the day so pollination of flowers would be light. They fly when temperatures are warmer, the sun is shining and wind is light. Put in some plants that flower during the winter that attract honeybees and it will help bring the few that are out there scavenging into your yard. One example is rosemary but there are many others. Freeze damage to American agave. You can reduce freezing damage to potentially tender plants somewhat by not fertilizing plants with high nitrogen fertilizers a couple of months before anticipated freeze.             In many places this was a “hard” freeze. Some landscapes were colder than others and this may affect fruit production in trees that were flowering or had small fruit on them. Electronic thermometers that record the previous days lowest temperature are not very expensive and may be worth having this time of year. By having one you will know the temperatures your landscape experienced. The extent of damage to plants relates to the lowest temperature, how long it lasted and the susceptibility of the plant to freezing temperatures. An older Taylor digital thermometer that remembers the last 10 days of low temperatures. It doesn’t give you a date but it gives you a sequence of days up to 10 days historically.Now they have wireless versions for less than $20.             If you applied fertilizer to your landscape plants already, or plan to soon, then all that the damaged plants need is water for recovery. If fruit is lost due to a hard freeze, there’s nothing you can do about it. If you plan to apply fertilizer soon, save some money and apply it when temperatures begin to warm.

Q. Is it too early to begin to hard prune Texas Rangers? We have a lot of them at our condo development. They have been sheared into balls over the years by our landscapers. If we could hard prune them now it would help our landscapers with scheduling other maintenance work. Texas Ranger pruned with a hedge shears A. Texas Ranger, or Texas Sage as it is sometimes called, should be pruned before flowers begin forming in early spring. Prune it hard, once in February, and don’t prune it again all season long. Remove as much of this shrub is you want, and it will come back with a little bit of fertilizer and water. Extremely Hard pruning of Texas Ranger             Consider pruning it 8 to 10 inches from the ground and don’t prune it anymore for the rest of the season. This should save your landscaping crew quite a bit of work! It will grow back quickly with water and fertilizer. Yes, it’s that easy. Don’t let your landscapers use a hedge shears on it repeatedly through the growing season. All they do is cut off the flowers and charge you for it.

Q. Please advise on how to prune pineapple guava. Flowers of pineapple guava A. It’s not clear if you are using these shrubs for their fruit or as an ornamental for its flowers. If you are harvesting fruit, then prune just after harvesting the fruit. If you are pruning it as an ornamental, prune after it flowers.             Don’t use a hedge shears. Instead, remove about one fourth of its entire canopy by reaching deep inside the shrub and cutting a stem with hand pruners just above a side branch. Perhaps 3 or 4 cuts like this is all that is necessary. Your cuts should be hidden, not easily seen, and removal of a stem should not leave a huge, gaping hole.             This type of pruning opens the shrub to sunlight, reduces its density, and causes more growth to occur throughout the canopy. It is done every 2 to 3 years and cleanup is quick and simple. Besides, it is the proper way to prune shrubs of this type.             Cutting only on the perimeter of the canopy with a hedge shears causes the shrub to become dense, boxy and not open to sunlight. This dense shading suppresses growth on the inside and, instead, stimulates growth only on the perimeter. The inside of the plant becomes leafless and woody.

Q. I want to grow gardenias. I live in the desert, and wondering what is the best soil and where I should plant gardenias in the yard? How much son do they need? Do they need to be kept in pots or planted in the ground? A. There are pluses and minuses when keeping gardenias in pots or containers; in some ways containers make growing gardenias easier and, in some ways, more difficult. But first things first.             Gardenias are not desert plants. The reality is, if you want to grow gardenias in the desert then they will cost more to maintain and take more time to properly care for them. They are native to tropical and semi tropical parts of the world that are non-desert. This means to grow them successfully, we need to try to emulate their native growing conditions as closely as possible. If you agree with that plan, then let’s get them planted! Light They need light for flowering but too much light will damage them because of the intensity of our desert sun. But planting them in too much shade will cause them to grow but not flower much. If it’s way too much shade, they won’t flower at all!             Typically, growing them on the east or north sides of a home, so they are shaded from the intense afternoon sunlight, will work. Soil The soil where they are planted should be amended so it is close to the soils in parts of Africa and Asia where they are native. This means amend or mix into the soil a good quality compost when planting. Dig the planting hole at least 3 times the diameter of the store-bought container. The hole doesn’t have to be deep, just wide because plant roots grow horizontally where the fertilizer is applied.             Don’t cover the soil around them with rock. Use a 3-inch depth of woodchips so that it decomposes into the soil and continue to improve it as it decomposes. A post about problems with woodchips Potted or not?  The good thing about containers is they can be moved to a different location if the first location is not the best. They can be moved into the garage if freezing temperatures are extreme. They can take temperatures down to 15° F. They are semi tropical plants so freezing could be a problem some extreme winters!             Secondly, container soils are isolated from bad landscape soils and can be amended much easier than landscape soils. But container plants require more upkeep. Every couple of years the plant should be removed from the container, the roots cut and the whole plant repotted with fresh soil. Another post on growing gardenias in pots Fertilizers Organic fertilizers such as compost are best but mineral fertilizers could be used if the soil is covered in decomposing woodchips. A single application of compost or a mineral fertilizer in mid-February is enough for general care but if these are your “pride and joy” then lightly fertilize these plants 3 or 4 times a year with a rose fertilizer.             To help prevent yellowing of the leaves during the growing season, add an iron fertilizer to the soil along with your first fertilizer application. Another post on iron in gardenias

Q. I am trying to revive and old grape vine that has been neglected. It produces plenty of grapes but poor quality. It has been untrimmed and unsupported for years. The trunk is rotted half way through and splitting. This was the only picture sent to me so there was not much to go on.  A. This year just get it growing and don’t worry about producing any fruit. This requires pruning, irrigating and an application of fertilizer all done in February. We can discuss this at my grape pruning classes on Fridays and Saturdays offered on Eventbrite. Great pruning classes offered on Eventbrite on Friday afternoon and Saturday morning.. Sign up for these classes here.  Remove excessive vine growth from the trunk. Select only 2 “arms” and leave only these attached to the trunk. Remove all the others. Cut these 2 arms back so they are each about 6 feet long. Support them so they are off the ground. Next, locate smaller branches coming from the “arms”. Prune back these smaller branches coming from the “arms”, so they are 12 inches long. These are called “canes”. Observe where the fruit was produced on these canes. Build a flat, dirt basin around the vine about 6 feet in diameter and 4 inches tall. Irrigate with about 30 gallons of water around the base of the vine and fill the basin with this water. Grapevine roots can be 30 feet deep or more. It will need this water to repair itself. There is a flat basin constructed around the trunk of this grapevine that is about 2 foot in diameter. They are being watered with bubblers and a basin. I usually use drip irrigation when they are in production. Here the basin has broken and leaking water so it needs to be fixed. After the soil has been wetted, apply a high nitrogen fertilizer, manure or compost in the basin and apply it no closer than 12 inches from the trunk. Use about 2 cups of fertilizer, or a 5-gallon bucket of manure or compost. Water this in with 5 to 10 gallons of water. Be sure not to apply this fertilizer, manure or compost near the trunk. This is granular fertilizer applied around fruit trees but you would do it the same way around a grape plant. Don’t get the fertilizer too close to the trunk. Water once a week in February to push new growth. You may or may not see flowering and berries depending on how much damage was done or how you prune it. Next year the fruit will be produced on growth from the current year. Where the fruit is produced on the cane will tell you if it should be “cane pruned” or “spur pruned”. When Cane pruning grapes, leave last year’s growth with about 10 buds. Follow good grape pruning practices in 2020. This year just get it growing and observe where the fruit is produced. These efforts may not improve the eating quality of the grapes appreciably. If you still don’t like the grapes, replace the vine. Note: I will post some information on my blog about how to prune grapes in a couple of weeks. Right now I would hold off pruning them until the weather begins to warm up.