Xtremehorticulture

Boxwood Hedge Slower to Recover From Pruning Damage Than Rosemary

Q. I have a neighbor concerned about his rosemary and boxwood hedges. The foliage has been falling off. Landscapers recommend he cut them to the ground to get them to recover but he opted to cut them back halfway instead. Now there is a lot of bare wood exposed with no leaves. What should he do to help them recover? A. When plants are continuously pruned with a hedge shears it causes them to get thick and bushy.             This increases their leaf density on the outer edges of the hedge. This causes the interior of the hedge to become very dark and the stems on the inside of the hedge to drop their leaves.             They also drop their leaves because the wood on the inside is old. All the new growth occurs where the hedge is being cut over and over. So perhaps only an inch or two along the outer surface of the hedge has leaves.             If we cut the hedge back more than a couple of inches, we expose the older wood that has no leaves. The wood is alive, but without leaves. Once this interior wood begins to receive sunlight again, new growth will sprout from this older wood.             The rate of growth from this older wood depends on the plant. Rosemary grows faster than boxwood. If he is patient, he will eventually start to see new growth coming from the older wood. Boxwood will also have new growth but will fill in slower than rosemary.             If he is patient both hedges will eventually slowly fill back in but boxwood will be much slower. In cases like these most people do not want to look at an ugly the hedge for the next few years and would elect to replace the damaged plants.             Once plants are cut with hedge shears for a few years over and over they are very difficult to reestablish again as plants that are not shaped like a hedge.

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Texas Ranger (Sage) Getting Woody

What should I do and when should I do it? Q. My Texas rangers have become very woody. Each have 2-2gph emitters and are watered for 40 min. 3 times each week. One is close to other plants and is probably stealing water from them. So, what should I do and when should I do it? A. Basically they have been pruned with a hedge shears or pruned like they were hedged. This has caused the outside of the canopy to become thin with lots of interior older wood. It will get progressively more like this with time and become more and more sparse unless the plants are allowed to get much larger. You have three options.             Let them get larger. This will allow them to put on sufficient new growth on the outside to cover up the sparseness of the foliage and the very old interior wood.             Second, you can do some corrective pruning. This may make them ugly for a couple of seasons but you will be on your way to re-establishing the plants with a better appearance and longer life. This would require two to three cuts deep inside the canopy, opening the canopy for new growth and re-establishing a new canopy. A caveat. I did not do this pruning but I saw it and it demonstrates an idea. The idea is the concept of renewal pruning. Renewal pruning is cutting back about 1/4 to 1/3 of the shrub every couple of years so that you have a “new” shrub every 6 to 10 years. This helps keep the shrub green from top to bottom and avoids it from getting woody at the base.             This will leave them looking like a gap-toothed 7 seven year old for a few months until they fill in. Next year remove two more and let it recover. By the third year you should have removed most of the older wood and the shrub should be well on its way to looking and performing better.             From that point forward you would renew prune the shrub every two or three years. This means that every two or three years you could take out maybe two of the oldest stems from the base and let it regrow out. That is all the pruning required on this plant. Another option is called rejuvenation pruning.This is basically cutting the shrub to within a couple of inches of the top of the soil or mulch and letting it regrow from these “stubs”. This does not work with all shrubs so make sure it works on the shrub you are thinking of doing it to before you do it. If you are not sure it will work on a specific shrub, cut one of the stems back to a couple of inches and watch what happens during the next growing season. Cutting shrubs down within a few inches of the soil or mulch surface is called rejuvenation pruning. Oleanders respond well to this type of pruning. Be careful though because not all shrubs will respond favorably to this drastic form of pruning.              Here is a shrub that was attacked by a hedge shears. Notice that there is sucker growth coming from the base. This is an excellent sign that this shrub is a candidate for either renewal or rejuvenation pruning.  Third is to pull them out and replace them and start pruning them the correct way which is without a hedge shears but two or three deep cuts every two to three years.

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