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Saturday, January 3, 2015

Can I Plant My Gift Hydrangea Outside?

Q. My kids sent me a hydrangea for the holidays.  I know I have to keep it as a houseplant.  When I lived in New York, mine were huge outdoors. What do I need to do keep them alive and thriving?

A. Hydrangeas are not meant for planting in our climate and soils. Hydrangeas given as gifts are like poinsettias; intended to be grown in greenhouses for a one-time gift event. But what the heck, give it a shot!
There are some varieties of hydrangeas that are more suitable for growing outdoors than others. Western Sunset Garden Book has recommended varieties you can try. If you are lucky enough to have gotten one of these varieties as a gift then you may have a fighting chance of keeping it alive.
They need a bright location on the north or east side with filtered light. Add compost to the soil at the time of planting. The plants need an organic surface mulch that decomposes, enriching the soil, such as wood chips. It should be fertilized with an acid fertilizer every 6 to 8 weeks.
If you want to go whole hog on this plant then get some aluminum sulfate and apply it to the soil when you plant and in early spring. Aluminum sulfate does a better job acidifying the soil than sulfur. Acidifying the soil helps keep the flowers of vibrant blue color.
You are fighting an uphill battle on this one but if you really want it to work you must spend time and money on this plant with soil preparation, mulch and specialized fertilizers such as aluminum sulfate.

Otherwise, I would not bother and enjoy it for what it was intended; a gift on a special occasion from loved ones.

What is Causing Citrus Leaves to Yellow?

Q. What is causing the leaves on my lemon tree to turn yellow?  This has been happening gradually all year.

Readers lemon leaves
A. Leaf yellowing of citrus is caused by any of these problems or in combination: high light intensity, micronutrient deficiency such as iron, irrigation and drainage problems and salinity. If the yellowing occurred during the winter and it was more of a bronze appearance then I would say it was due to winter cold.

Looking at the picture you sent, some of the leaves have leaf tip burn. That could be caused by salinity or a lack of water. It is possible it could also be too much water or poor drainage but I don't think this is the case unless you are watering it several times a week.
Without more information I am guessing it is a combination of high light intensity, micronutrient deficiency and possibly salts. If the leaves were more “bronzy” looking I might also conclude it could be high light intensity if it is in a location with lots of reflected light.
Yellowing of citrus leaves due to high light intensity

Flush salts from the soil. Apply a large volume of water to the irrigated area under the tree to flush salts that might be causing a problem. Do this two or three times over a period of a few days then revert back to normal irrigations.
Water no more than every ten days right now. Make sure the volume of water is sufficient to wet the soil 18 inches deep. When new growth resumes, resort to irrigating more often but this time of the year irrigating 10 days apart should be adequate.
Unkinown nutrient deficiency of citrus but probably manganese or iron. Since iron deficiency is common in the Las Vegas Valley the KISS principle tells us to treat for iron

If there is rock surrounding the tree, pull it a distance of 3 feet away from the trunk. If wood mulch surrounds the tree, you do not need to pull it back. Make sure wood mulch does not contact the trunk of young trees. Keep wood mulch 6 inches away from the trunk.
Next, apply iron chelate containing EDDHA beneath the tree in January near a source of water. Cover the iron chelate with wood mulch to keep it out of the sun or make sure it is placed beneath the soil surface.

Magnesium deficiency of citrus
Next February or after fruit set apply a normal amount of fertilizer. Organic fertilizers are best. You should see a change in the color of the new leaves next spring during growth.

Monday, December 29, 2014

What Causes Brown Leaves on Yucca?

Q. Why are the tips of my yucca leaves turning brown? 
Brown leaf tips on yucca. Can be from soil or irrigation problems.
A. This is pretty common on yucca in our climate and soils unless they are grown in filtered sunlight and the soil has been prepared well before planting. They always tend to have brown tips. In the case of your plant, judging from your picture, it does seem excessive.
When we see brown tips on the foliage of desert plants it usually means a watering problem, a soil salt problem or lack of drainage.
This particular yucca is native to the Chihuahuan desert so infrequent irrigation is critical to its health. Most of the soils in the Chihuahuan desert are better than our landscape soils created by the builders of our homes.
Regarding your irrigations, compare your watering with how these plants might be watered in their natural habitat. This is a guideline for how you should water. They won’t need watering that often so if you are watering more frequently than every two or three weeks in midsummer, I would suggest this is too often.
If this plant is on the same irrigation circuit as other landscape plants, and these other plants are not a desert plants, then I would suggest the plant is being watered too often.
The volume of water you give the plant is not as critical as the frequency it receives water. In other words, you can give it a large volume of water and not hurt the plant as long as you wait long enough before the next irrigation. Giving large volumes of water may waste water but it seldom keeps the soil too moist for the plant between irrigations.
If this plant is watered too often, remove it from that irrigation circuit and water it by hand every few weeks. It will like a couple of deep winter irrigations, a spring irrigation, a couple of midsummer irrigations and a fall irrigation and that's about it.
If the applied water is close to the trunk, then the trunk could be rotting. Keep frequent irrigations away from the trunk. However, it is okay to water in a large basin beneath the plant if it is done infrequently.

If there are other plants around it, it is probably getting enough water from its neighbors. But I would still give it an occasional drink to be on the safe side.

Can I Apply Iron in the Winter?

Q. I have a dwarf lemon tree with many yellow leaves. Can I add iron at this time of year (December)?
This is not citrus but it is iron chlorosis. You can tell from the yellowing of the leaf while the veins remain green and appearing on the newest growth. It is possible to confuse it with manganese deficiency easily.

A. If you apply iron this time of year (December) it is best applied as a foliar spray rather than to the soil. If the leaf yellowing is not extensive you could wait until spring. Leaf yellowing reduces a plant’s ability to capture sunlight and produce energy to maintain its growth and health.
Iron chelate made for applying mixed with water. 

If you want to correct it now, you must apply iron to the leaves as a liquid or foliar spray. It is best to use an iron chelate mixed with water and add about 1 tablespoon of white vinegar if you use tap water to reduce the alkalinity. If you use distilled water, you will not need the vinegar.  To this water add the appropriate amount of iron chelate listed on the label. You should add a wetting agent to help the spray penetrate the leaves.
You can make your own wetting agent by using a liquid detergent like Dawn or Ivory Liquid at a rate of about 2 teaspoons per gallon added to the finished spray mix. It is not as refined as a commercial wetting agent but it will do the job.
A very safe wetting agent for better leaf penetration

You would apply this mixture of water, chelate and wetting agent to the leaves immediately after mixing it until the spray runs off the leaf surface. Let the leaves dry and repeat it a few days apart or until you see the leaf color change from yellow to a darker green.
Foliar sprays like these may require several applications to get the results you desire.  Citrus leaves have a very waxy surface and are difficult to penetrate with just plain water. If you use tap water then each time you prepare a new spray you should adjust the alkalinity of the water with vinegar and add a wetting agent.
Foliar sprays should always be freshly made, applied immediately and not stored for any length of time. Unfortunately homemade iron liquids, unlike commercial sprays, do not store very well. It might be cheaper in the long run to buy the liquid iron spray already made and make the application.
It is also possible citrus leaf yellowing could be a magnesium or manganese problem. Liquid iron sprays will not correct problems due to magnesium or manganese.

Radishes Are the Perfect Winter Vegetable for Beginner Gardeners

Radishes are the perfect winter crop for the beginner gardener in the ground, raised beds or containers. They are easy to grow, will germinate at very low soil temperatures and will mature for harvesting in as little as 30 days. Don't plant them too deeply and to speed germination cover with some clear plastic to keep the soil warm. Remove the plastic after you've seen them germinate.

Space the seed in rows or in blocks so that the seed is about 1 to 2 inches apart from each other. In our Las Vegas climate you should be able to get 5 to 6 crops during the fall, winter and spring seasons when they are the sweetest.

Find some hybrid varieties which will reduce the heat or spiciness if you don't like that. The tops can be eaten in a salad or cooked as greens just like mustard greens. The oil that you use in cooking greens has a big impact on the flavor of cooked greens.

French breakfast radish after 30 days

Spacing of radish seeds. If radishes are too close together they will not produce large bottoms.

Brown Ugly Space Alien in the Garden

Recently I found this brown space alien into one of our raised beds. This is the pupa, or resting phase, of the tomato hornworm. This is the stage of development between the worm or larva and the adult hummingbird or sphinx moth. This insect is a voracious feeder of all garden plants but particularly tomatoes, peppers, eggplant and even grapes!

This insect will overwinter in this stage and emerge again in the spring as the adult hummingbird moth. It will find a mate by flying at dusk and lay eggs on plants that it likes to eat. The eggs will hatch into a miniature hornworm and voraciously grow into the much larger version.
Hummingbird or Sphinx moth
Right now you can dispose of them. But later in the spring after planting you will want to protect your plants with either Bt or Spinosad.
Bt can be found under the names of Dipel or Thuricide as well.
One of the names for Spinosad. Check the ingredients

Delay Pruning Grapes Until Very Cold is Past

Q. I usually prune my grapes when I do the roses but would like to get a jump on it this year. Will I do them any harm if I prune them now (December)?

A. You can do it but I worry a little bit about possible freezing damage if these are winter tender grapes and desiccation. Some grapes are less cold hardy than others. For instance, Thompson seedless has some wine grape heritage (vinifera) and tends to be less cold hardy than some other table types.

I have noticed in our desert climate that we can also get winter desiccation (drying out) in windy locations. Those grapes which are pruned to spurs usually leave only one or two buds which means the spur may only be one half inch long after pruning. If we lose this half inch of growth from winter cold or desiccation, then we have lost our crop for the season.

I usually delay it until almost the first week in March when buds are starting to swell. By delaying it I can prune out the dead wood that occurs during the cold winter months and focus on the stuff that is still alive. I would wait.

Swarming Bugs; Ants or Termites?

Q.  We were out in our yard last weekend putting up decorations when we noticed small bugs flying up out of our yard. They were thick groups of them coming out of small holes that looked like grains of rice clumped together in bunches. There had to be thousands of them. The "exodus" lasted for about an hour and then it was done with no sign they had been there.  Can you tell what they are?  Are they harmful?  Do we need to do something to get rid of them?
Flying ants or termites. The length of the wings suggests termites but a visual check of the bodies and antennae need to be done.
A. These look like winged ants or possibly winged termites. It was difficult to tell from your picture. They both swarm in identical fashions. The ants are just a nuisance. If these are termites then you may have a problem.
You need to catch some of these insects and look at their body shape, antennae and length of their wings. Ants have a constricted waist or segmented body parts. Termites do not have these segmented body parts and body parts are not as easy to distinguish. 
I have provided a link on my blog for you to follow or you can type the following into your search engine that will help you identify the difference between the two different insects. 
If you believe these are termites contact a reliable pest control company and schedule a follow-up.

Follow the link below or on my blog to read information about flying ants from Colorado State University. More about flying ants

When Should I Winter Prune Flowering Plants?

Q. I have some bushes and shrubs in my backyard that still seem to be blooming. How do I know when they are ready to be trimmed back?

A. Sometimes we have to prune them back to make way for new growth in the spring. For small plants that get a lot of woody growth at the base, let them go through the winter and trim them back after all of the very cold weather has passed this winter. That is usually by mid-February.
Lantana after winter pruning. This was actually left too long. Prune closer to the ground. After pruning, this is what you will look at until February.

Pruning of ornamentals is all about appearance. If it looks bad to you, go ahead and prune it back. You will not hurt the plant. My major concern about pruning too early is the possibility of freezing damage and creating more work for yourself. If you prune now and we get more freezing weather then you will have to prune a second time.

Waiting until the end of the coldest part of the winter avoids pruning a second time. But if you like to go out in the yard and tinker, prune when you need to. It won't bother the plant.