Xtremehorticulture

Hibiscus Grows Differently in the Desert

Q. My hibiscus plant, transplanted from a pot to my outdoor flower bed, is blooming like it should. But the leaves are not getting any bigger than 1 – 1½” long and ¾” wide. The new leaves also only get to that size. I water and fertilize if with Miracle Grow regularly, but that does not help. Any suggestions? A. The appearance of plants will be different when grown in different climate zones. I am now on my farm in the Philippines where we have Roselle hibiscus (commonly called Red Zinger) growing. I checked the size of the leaves in response to your email. I normally don’t pay much attention to leaf size just flower production. Roselle growing on our Family Farm in the Philippines             The leaves of our Roselle vary in size from the narrowest at about 3 to 4 inches in length and about 2 inches wide to the largest being 6 to 8 inches long and 4 to 5 inches wide. The largest leaves are growing in partial shade. The smaller leaves are growing in full sun. Tropical hibiscus growing in the Philippines in a tropical climate.             Appearance can also be impacted by your management practices. Let’s cover a few of these.             Climate and microclimates. Plants grown under high light intensities have a different appearance than plants grown under lower light intensities. The principal differences are in leaf size, color and thickness.             Leaves growing under higher light intensities, provided they are getting enough water and nutrients, will be dark green, smaller, thicker or tougher and develop a thick waxy coating on the leaf surface.             The same plant growing under lower light intensities will have larger and thinner leaves with a waxy coating that is not as thick. If light intensities get extremely high then we will see leaf discoloration, yellowing or bronzing, on some plants because the light intensity is actually damaging the leaves. Red hibiscus growing in rock mulch in Las Vegas             If the same plant does not receive enough light then the plant will become “leggy” with large distances between the leaves and thin stems that will not support its own weight. The plant will become “floppy”.             Our job as a manager of this plant is to find a good location in our landscape that provides the right microclimate which provides enough light for flowering and an appearance close to what we expect.             Because we are in a desert, Hibiscus will not look similar to those grown in semi tropical or tropical climates but we can approach that look if we are careful where we plant it.             Soil. Organic matter such as compost mixed into the soil at the time of planting and applied annually to the soil surface surrounding the plant will encourage larger and healthier leaves. I have seen this numerous times on a number of plants particularly in parts of the plants that are shaded such as lower leaves. Red hibiscus growing in rock mulch in Las Vegas showing signs of leaf drop, leaf yellowing and branch dieback.             Fertilizer. Fertilizer will influence the kind of growth. We know that phosphorus fertilizers are very important for flowering, fruiting, root development and production of oils in plants. If not enough phosphorus is present it will impact these types of growth.             We do not need to apply phosphorus to a soil very often unless it is extremely sandy or growing in hydroponics.             Nitrogen is different. Nitrogen is important for developing dark green color in leaves and stems and for “pushing” new growth. It is important in producing good leaf size and in the number of leaves and supporting stems produced.             Nitrogen in soil available to plants also dissolves easily in water. Nitrogen is easily does not dissolve in water easily and is slowly released to plants.             In your case you want to make sure that nitrogen is applied regularly through the growing season to maintain dark green color and “push” new growth. Combined with moderate amounts of shade, nitrogen will encourage more leaves and larger leaves.             What should you do? Understand that if your hibiscus is in a very hot, bright location that this location will limit the plants ability to produce larger leaves. Moderate amounts of shade will encourage larger leaf development, particularly in a microclimate that gets morning sun but afternoon shade.             Apply a 1 inch layer of compost and scratch it into the soil surrounding the plant as much as you can. When you’re done doing this, apply another 1 inch of compost to the soil surface and thoroughly wet the soil deeply. Apply a 1 inch layer of compost to the soil surface every year.             Apply high nitrogen fertilizer at the beginning of the growing season. Apply a high phosphorus fertilizer after it is finished blooming. If you apply fertilizers at other times of the year, apply liquid fertilizers to the leaves.             Do not apply any nitrogen fertilizers to the soil after August 1 if you are concerned about winter freezing damage. 

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Mesquite Bushes Can Be Trained to a Tree

Q. I grew up in a part of Texas where mesquites were bushes not trees.  We have a small backyard here in Vegas with two mesquite trees in it; one large one and one slender one. There is little or no green on them, just wood. There are so many woody branches I am wondering if they will ever give us shade.  Would you please educate me on this? Native honey mesquite growing in the Mojave Desert just outside of Las Vegas, NV A. The Texas mesquite or honey mesquite is a shrub that we prune into a tree form. The plant grows well here but is usually not a preferred type of mesquite because of its long thorns. There are improved types of mesquites that are usually preferred.             With a little bit of care when they are young they can be trained into a tree form.             In our climate many mesquites drop their leaves in winter and so are considered deciduous to semi evergreen due to winter cold. In warmer climates they tend to stay evergreen during the winter unless there is a cold spell.  One of the ornamental mesquites in the nursery trade, claimed to be thornless, showing dense canopy and shade, a sign of abundant water.             We consider our local mesquite to be a riparian species of plant. In other words it puts on growth when water is available and slows down when water is not. When mesquite trees are watered frequently they can put on large amounts of spindly growth, perhaps 8 feet or more each year.             Mesquite are normally very deep rooted plants in the wild. Being deep-rooted gives them the capability of avoiding long periods of time without water. For this reason they can be very drought tolerant if they have rooted deeply. Native mesquite growing in the Sonoran Desert near Jerez, Mex, demonstrating sinker roots tapping into deep water from a nearby river.              If mesquite trees are watered too often, their roots will tend to be shallow and not deep-rooted, a frequent problem in over-irrigated landscapes. They also tend to put on a lot of wood because of frequent irrigations.             Mesquite trees handle pruning very well and their growth is very adaptable to landscape management. They do well with light fertilizer applications annually. They should be grouped with other desert plants for irrigation purposes.             After training these plants into a tree form they do not require a lot of pruning. In fact heavy pruning just encourages a lot of new growth. I would remove lower branches just high enough to allow traffic to pass under them.             Frequent irrigations will cause these plants to be lush and provide dense shade. Watering less often will cause them to become more open and provide lighter shade. Remove branches that are crossing or growing too close together.             Limbs would be removed at their point of origin, not by hedging or simply cutting them back.

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