Grapes only grow on wood that grew previous year

Q: I have had a grapevine for the last six years. The first year when I planted it, I didn’t get grapes but years two, three and four, I had lots. Last year my vine grew leaves and it was time for the baby grapes to show up, but they never did. We’re in the middle of May and I’m wondering what is wrong with my grapevine.

A: Fruit of grapevines is produced only on wood that grew the previous year. It does not grow on new growth. It does not grow on 2-year-old wood. Second-year wood is the only place that can produce flowers and fruit.

If all of the previous year’s wood is removed or dies, there can be no flowers or fruit. On the flipside, if the vine is left to grow every year without pruning or dying back it will produce lots of flowers and fruit. However in future years there will be problems of crowding, fruit rots, disease, etc.

If a grapevine is pruned too much and all of last year’s growth is removed, it will produce lots of new shoots but no flowers or fruit.

Either last year’s growth died or it was pruned out. That’s why you don’t have grapes.

Q: Is salt cedar wood OK to use as mulch?

A: Mulch is anything applied to the soil surface that reduces weeds and evaporation of water from the soil. Mulch can include wood chips, rock mulch, straw or even plastic. When wood chips are used, however, it also improves the soil as it decomposes.

Salt cedar is a tree with a big environmental problem in the Western United States. It is invasive along waterways, chokes out other plants and dominates an area once it becomes established. There has been a lot of talk and effort aimed at eliminating this tree and put its remains to beneficial use after it has been cut down.

Here’s the rub. Salt cedar does not produce a lot of heat when used as a fuel. So burning it for that purpose has been discouraging. Chipping the wood to use in landscapes as a mulch was thought to be a possibility, but using it for that purpose is problematic.

There are two major problems when salt cedar is used for a mulch. First are the seeds. One tree produces millions of seed. The seed germinates easily. Using it for a mulch would spread seed everywhere.

The second is salt. Salt cedar gets its name because it pulls salt from the soil and concentrates it in its leaves. By dropping its salty leaves on the ground it prevents other plants from growing beneath it.

Using salt cedar as a mulch will cause many new seedlings to pop up everywhere and apply salt to the landscape wherever this mulch is applied.

If you could use only the wood without the leaves or needles, it might be all right as a wood chip mulch.

Q: We have a split leaf philodendron that is starting to bear fruit. We are hoping you could advise us on when and how to harvest the fruit.

A: What we call split leaf philodendron, or Swiss cheese plant, is actually not a philodendron at all. This vine is also called Mexican breadfruit in other parts of the world because the fruit is edible and fruity in taste. Although not hugely popular, you can sometimes find it for sale in markets selling tropical fruit.

The fruit is not edible until it is fully ripe. The cone-shaped fruit changes color from green to light green indicating it is close to maturity.

When it reaches this color, cut off the fruit with a little bit of the stem attached and let it ripen on the kitchen counter. The fruit is covered in scales that can be removed once the fruit is soft.

Wait for it to get soft so that you know it’s ripe. Eating it while it is still green can irritate your throat and mouth.

Q: My new apple tree had at least 18 inches of new growth since spring. Last year when I cut these long shoots back it caused the tree to not produce any flowers. I’m assuming that flowering only occurs at the end of the branch until it forms side shoots. My apricot didn’t produce any flowers at all but it is a young tree.

A: Most apples and all apricots produce fruit from short shoots along branches called spurs. Apples and apricots don’t bloom at the ends of branches. They only bloom on these short shoots.

If trees are vigorous and produce very long branches, cutting them back so they aren’t quite so long helps produce fruiting spurs closer to the trunk. Allowing them to grow to 3 or 4 feet puts long spaces between fruiting spurs.

Fruit trees that produce fruit on spurs take a year or two longer to set fruit compared to peaches and nectarines. If you want to keep your fruit close to the trunk and the tree more compact, always cut back long shoots to about 18 to 24 inches. Cutting these long branches back helps slow growth and makes more compact.

Extra-long branches might also occur because too much fertilizer was applied. Cut the applied fertilizer in half next growing season.

Q: I would like my 3-year-old mesquite tree to grow taller. It seems they are growing like a bush.

A: If you want any tree to grow taller and faster, then reduce the total number of branches in the canopy and water frequently.

Plants grow taller and more quickly if there are fewer branches. Remove about one third of the branches from this tree. Remove them by cutting these branches back to the trunk or a major limb.

Resist the temptation to stub branches back. Stubbing the branches slows growth and causes the canopy to become compact and bushy.

Don’t water frequently but give them plenty of water when you do water them. Growth of mesquite responds to water. When water is present, they grow rapidly.

Fertilize them with high nitrogen fertilizers. Apply high nitrogen fertilizers every two months until August and make sure to water the fertilizer into the soil.

Q: I bought a lemon tree about a year ago. Now it has leaves only on bottom.

A: The usual reason for leaves only on the bottom of a tree is because of freezing temperatures during winter causing the tops to die while the bottom of the plant survives.

Look at the trunk of this tree carefully. At 1 to 3 inches above the soil is a place where the trunk is not straight. We sometimes call this a dogleg. This is the location where the tree was grafted.

Lemon trees are joined, or grafted, to the roots of a different citrus at this dogleg. If new spring growth is coming below the dogleg then the lemon part of the tree is dead. If this is the case, dig it up and throw it out.

If new growth is coming from above this dogleg then you can save it. Cut just above the new growth and let it grow back.

It is also possible that the tree can be damaged if it is not receiving enough water each time it is applied. Create a basin around the tree that holds 10 to 15 gallons of water.

Always apply water inside this basin where it will be contained and water all of the roots of the plant deeply. Without this basin, it will be difficult to give the plant enough water.

If this tree is watered by drip irrigation, then replace the drip emitters with emitters that provide more water or add more emitters around the plant.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.