Q: I am trying to revive an old grapevine that has been neglected. It produces plenty of grapes but of poor quality. It has been untrimmed and unsupported for years. The trunk is rotted halfway through and splitting.
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 Fridays and Saturdays offered on Eventbrite.
Remove excessive vine growth from the trunk. Select only two “arms” and leave only these attached to the trunk. Remove all the others. Cut these two 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.
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.
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.
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.
Q: I want to grow gardenias. I live in the desert and wonder what is the best soil and where I should plant gardenias in the yard. How much sun 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 other 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.
They are native to tropical and semitropical parts of the world that are nondesert. 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 side of a home so they are shaded from the intense afternoon sunlight will work.
Dig the planting hole at least three 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.
* 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 degrees 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.
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 three or four 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.
Q: Please advise on how to prune pineapple guava.
A: It’s not clear if you are using the shrub for its 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 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 three or four cuts like this are 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 two to three 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 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: 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.
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.
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 hedge shears on it repeatedly through the growing season. All they do is cut off the flowers and charge you for 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.