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Wednesday, December 11, 2013

UNCE Orchard in North Las Vegas Posts Hard Freeze Temperatures in December 2013

Earlier this month the UNCE Orchard in North Las Vegas (located near the intersection of North Decatur and Horse Drive) posted some very low freezing temperatures.  Winter tender plants will be killed to the ground at these temperatures. In particular bougainvillea and any tender vegetables (tomatoes, peppers, squash, basil, etc). Tender citrus will be damaged or outright killed to the soil level. Hardy citrus that will handle these temperatures include Meyer lemon and some grapefruit. Expect to see some bronzing of the leaves of palms and citrus.

UNCE Orchard Weather Station Report From 2013-12-04 To 2013-12-10
Reported by Mike Barrett
          __________Temperature________   Degree    Solar     RH     Rain-   ___   Wind___
    Date   Mean  High   Time    Low    Time     Days    Rad       Mean   Fall       Speed Gust
   12/04   36.5    44.7  14:30   25.0   00:00      0.0       153.7      40     0.00          5.3    26.0
   12/05   31.6    42.1  14:30   22.4   06:30      0.0       151.3      41     0.00          0.2      7.0
   12/06   31.5    42.2  14:30   20.9   07:00      0.0       148.1      45     0.00          0.5    10.0
   12/07   40.2    52.8  14:30   27.6   00:30      0.2       131.6      42     0.00          4.0    19.0
   12/08   34.2    41.2  13:00   27.8   05:30      0.0       145.0      17     0.00          3.6    17.0
   12/09   31.7    40.3  14:00   22.9   23:30      0.0       150.6      17     0.00          4.9    20.0
   12/10   22.6    28.4  08:00   20.3   04:30      0.0         20.9      42     0.00          0.0      2.0
                                                                        0.2                               0.00           

The Watchdog 2900ET weather station is located near the northwest corner of the south orchard, approximately 2.5 meters above ground, at the top of the tree canopy.

Temperature – degrees F (±1ºF)
Solar Radiation – Watts/m2 (±0.05)
RH – Relative humidity (±3%)
Rainfall – inches (±4%)
Wind – miles per hour (±5%)

Tuesday, December 10, 2013

Vegetable Planting Calendar for the Mojave Desert

Calendar of planting (2000 foot (700m) elevation in Southern Nevada @ 36 deg N Lat.)

If closer to 3000 feet, delay planting 2 to 3 weeks in the spring; plant earlier 2 to 3 weeks in the fall. If row crop covers are used, planting can be 2 to 3 weeks earlier in the spring and 2 to 3 weeks later in the fall on some vegetables. If hoophouses are used, planting can be four to six weeks earlier in the spring and 4 to 6 weeks later in the fall. These are approximate dates. Current weather conditions and soil temperatures must be monitored for the exact timing.

Beets, broccoli as transplants, radish, Spinach, Swiss chard, roasting garlic

Beets, broccoli as seed, broccoli as transplants, Brussels sprouts, cabbage as transplants, carrots, sweet corn (later in the month), kale, lettuce, onion sets, potato (later in the month), radish, spinach, Swiss chard, turnip

Bush beans, broccoli seed, broccoli as transplants, brussels sprouts, cabbage transplants, carrots, sweet corn, eggplant late in the month, green beans, pole beans, kale, kohlrabi, lettuce, onion sets, onions as transplants, peppers late in the month, potatoes, radishes, spinach, Swiss chard, tomato late in the month, turnip

sweet corn, cucumber, eggplant, green beans, pole beans, melons late in the month, peppers, tomatoes, summer squash

cucumber, eggplant, melons, peppers, sweet potato, summer squash


sweet corn late in the month, green beans, pole beans, melons

beets, broccoli from seed, broccoli from transplants late in the month, cabbage transplants late in the month, cauliflower transplants late in the month, sweet corn early in the month, green beans, pole beans, spinach, Swiss chard, winter squash at lower elevations

beets, broccoli from seed, broccoli from transplants, cabbage transplants, cauliflower transplants, carrots, kale, lettuce late in the month, spinach, Swiss chard

beets, broccoli from seed, broccoli from transplants, cabbage transplants, cauliflower transplants, carrots, garlic, green beans, pole beans, kohlrabi, lettuce, radish, spinach, Swiss chard, tomato

beets, broccoli from seed, broccoli transplants, carrots early in the month, green beans, pole beans, onion seeds, peas, radish, turnip,

beets, broccoli from seed, green beans, pole beans, spinach, Swiss chard

Acidifying Soil and Water Can Be Beneficial for Desert Soils and Sprays

Q. Have you ever heard of adding vinegar or citric acid when fertilizing plants in our area?

A. Quite a few people have thought about it or tried it but the positive impact on the soil is short-lived and is usually considered not worth doing. Gardeners realize our soil is much more alkaline than the ideal garden soil. Methods used to acidify soils are frequent gardening topics. This includes the addition of acids such as acetic or vinegar and adding sulfur.
Sulfur granules can sit on the surface of a desert soil for months or even years if it never comes in contact with water or is not ground finely. This does not help lower soil pH.
            Our soils and our tap water from Lake Mead carry a lot of lime so the addition of anything to the soil to make it more acidic is usually short-lived.  A fairly effective long-term method for improving our soil is the addition of compost or other sources of organic matter that decompose, acidifying the soil as it does so.
            However, adding weak acids to the soil is a short-term solution. How much acid to add to a soil is another question altogether. Much of that depends on the chemistry of the soil itself and varies from soil to soil.
            Acidifying water used for foliar applications of a pesticide or fertilizer is a different story. This water should always be acidified to pH around 6.5 before adding the pesticide or fertilizer. The easiest way to measure this pH is with litmus paper, the type used for swimming pools or aquariums. Another option would be to use distilled or reverse osmosis water instead.

Tropical Dragonfruit a Possibility for Backyard Culture in Las Vegas

Q. I am interested in raising dragonfruit.  Any suggestions or comments?

A. The dragonfruit plant is a tropical climbing cactus that originated from Central and South America. The plant produces large edible fruit covered in scales. The edible fruit interior has a bland taste resembling watermelon or Kiwi with slight citrus overtones.
Dragonfruit is produced by a "climbing" cactus.
            There are several different varieties with skin colors ranging from green, yellow or red. The flesh, pulp or interior of the fruit is normally white but in some varieties it can be various shades of red.
Here in a small orchard in south vietnam the vegetative cuttings are planted next to a cement post that will be used for trellising
            Several other cacti also produce similar types of large edible fruit. Collectively these fruits are called pitaya.  The cereus cactus is commonly grown in the Las Vegas area, can withstand our cold winter temperatures and may on rare occasions produce a pitaya fruit.
Although not dragonfruit or cereus, flowers typical of pitayas
            Many of the pitaya-producing cacti have large white flowers that only open at night and frequently are very aromatic.  Moths or bats are usually responsible for pollinating these night blooming flowers. Many pitaya require cross pollination in order to set fruit and so a second plant in the vicinity may be necessary.
Dragonfruit cactus in full production, trellised, in south vietnam
            The dragonfruit plant itself is very sensitive to frost and harsh light intensities and must be protected from freezing weather. It will also benefit by being grown in a part of the landscape protected from late afternoon sun.
            Just for fun, the plant can be started easily from seed collected from the fruit. The seed is small so you would plant it very shallow in good planting soil. The seed should germinate in about two weeks in warm soils.
            However, commercially the plant is started from stem cuttings to maintain plants that are true to type.

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.

Bulbs Forming on Top of Garlic

Q. My garlic planted last year has a small bulb forming at the top of a few of the plants. From what I read about this type of plant the garlic is formed from the bulb at the top. Do they reproduce underground for future plantings?

Bulbils forming on top of hardneck garlic at UNCE orchard
A. We do find some garlic producing these small bulbs at the tops of the plants. They are sometimes referred to as bulblets or bulbils depending on who you talk to. These plants will also produce bulbs which can be used for planting the following year.
            In the same family of vegetables there are onions which do the same thing. These are called “walking onions”. The flower at the top of the flower stalk, or scape, does not produce seed but produces miniature bulbs instead.
            These bulbils are capable of reproducing the mother plant. They are called “walking onions” because the weight of the bulbils bends the scape over to the ground. If the soil is wet, these bulbils grow into new plants just inches from the mother plant. This new growth gives the perception that these onions are “walking” or moving from one location to another.
            These types of plants can be self-seeding by dropping the bulbils into the garden and starting new plants perpetually.
            Most garlic that produces bulbils are hardnecked types of garlic or sometimes referred to as “topsetting” garlic. They are called hardnecked because the flower stalk is very rigid compared to the “softneck” varieties which can actually be braided.
            So to answer your question, yes you can plant these bulbils and they will produce new plants. It is good to remember that the size of the clove or bulbil you plant will impact the size of the bulb you produce. The larger the clove or bulbil, the larger the bulb.