Keep irrigations further apart in winter months

     By Bob Morris
     View columnist
      The following are typical questions our Master Gardeners answer daily at the Nevada Cooperative Extension. If you have gardening questions, call the Master Gardeners' hot line at 257-5555 between 9 a.m. and 4 p.m. Monday through Friday. There is also a gardening Web site at http://www. intermind.net/mgarden./
     
      There have been some questions concerning how long to set drip irrigation this time of year. Remember, when setting drip it is never set to run for just a few minutes. The length of time should be long enough to wet the soil to the depth of the root system. If this is for trees and shrubs, water needs to penetrate to a depth of 18 to 24 inches.
      After enough water has been applied to accomplish this, the water should not be applied again until the soil around the roots has dried adequately.
      This may take a week in the summer and as much as four weeks in the winter. The point is that the soil should dry out before the next watering. If it doesn't then plants that are sensitive to overwatering will die.
      If plants have been established for at least one year after planting, I would guess that drip irrigations should be at least one week apart during the winter. In fact, I would be very surprised if the time between irrigations couldn't be much longer than that. In the case of desert plants, the irrigations should be much further apart.
      Question: I finally got lemons on my Meyer lemon tree. Why is my Meyer lemon not sweet?
      Answer: Meyer lemons were introduced to the U.S. from China in 1908. It is not a true lemon and mature fruit resembles an orange. It is commonly grown for ornament and the fruit is used as a lemon substitute, although a small commercial industry for fresh market and processing exists.
      The flesh is light orange-yellow, moderately seedy and juicy but is much less acidic than true lemons. However it is not a sweet lemon. The tree is spreading, small in size, nearly thornless and more cold tolerant than true lemons.
      It can be grown towards the northern end of the citrus belt and can possibly make it through our winters if we don't get temperatures this winter in the teens.
      The true lemon apparently originated in northwestern India, though little is known about its origin and subsequent spread. It was first grown commercially in southern Italy and Sicily and was brought to the New World by Columbus in 1493.
      There are basically only two types of lemons, based upon characteristics of the tree, Eureka and Lisbon. The true lemon fruit characteristics do not vary appreciably among varieties. Eureka originated in California where it is the major variety. Lisbon originated in Australia. There are a number of other varieties that are selections from either Lisbon or Eureka.
      Q: I have this white powder on the soil where I want to raise vegetables. Will this spot be OK for a vegetable bed? What should I do with it?
      A: The white powder on the surface of the soil is a salt of some sort or combination of many different salts found in the soil and left on the surface after evaporation.
      The type of salt depends on the minerals in the soil. The safest way to deal with it is to remove this layer of soil that contains the salt and dispose of it somewhere outside the vegetable garden.
      There are a number of vegetables that are not very salt tolerant and this amount of salt could damage salt-sensitive vegetables. Many other landscape plants and lawn grasses are much more salt tolerant and can withstand these types of salts.
      Generally speaking, flowerbeds are another place where salts could be a problem depending on which flowers you grow.
      If you are going to use the existing soil in that spot for the garden the soil needs to be leached with good, clean water.
      The best way to do this is to test the soil for salinity and determine just how much salt is present. For a vegetable garden, the salts should be at a minimum. Vegetables like beans and radishes are very sensitive to salts and will not do well even if a small amount of salts are present.
      I would recommend you use a raised bed and bring in a good planting soil from a local supplier rather than use that soil.
      Q: We purchased a living Christmas tree this year and we are concerned about how long it should stay in the house. What should we do?
      A: You should be somewhat concerned about that. When you purchased the tree it was outside, in the cold, in a somewhat dormant state. The cold fall temperatures and the shortened days combined to signal the tree that winter was approaching and enter into this period of rest.
      As it enters this period of rest, changes inside the tree protect it from freezing temperatures that it would not normally experience in the summer.
      The tree will stay in this condition until it senses winter is over and it's safe to grow again. Trees coming from our part of the world must have these seasonal changes or they will eventually die.
      The next signals the tree would respond to are warmer temperatures and increasing day length. These signals trigger the tree into changes that mean spring growth is near. In other words, the tree will begin to get everything ready for new growth when it senses warmer temperatures.
      Bringing a living Christmas tree inside the house for a long period of time may be enough to send a signal to the tree that winter is over.
      This might not necessarily be bad if all danger of freezing is past. If a tree that has been in the house for a long time and then is taken outside where it experiences very low temperatures, damage to the tree could result.
      The best recommendation would be to keep the tree inside the house for a short time after the holidays.
      I'm relatively confident that two weeks inside the house will not be a problem for the tree but much of that depends on the type of tree and its health prior to its purchase.
     
     Bob Morris is a horticulture specialist with Nevada Cooperative Extension.