​Horticultural Tips for April 2019
 
Houseplants

1. Start fertilizing now for spring and summer growth.
2. Fertilize your holiday amaryllis and keep it in high light to encourage new leaves.
3. Don’t even think about moving houseplants outside until night temperatures are above 55 degrees. 

  
Garden

1. Iris borer eggs hatch in April and May.  Remove last year’s foliage as soon as possible this month.  NEVER mulch up to the iris foliage.  That will encourage tuber rot and hide borer damage.
2. Cut back last year’s growth from perennials.
3. No matter how much you are tempted, DO NOT remove or braid the green foliage of bulbs as those leaves feed the bulbs so that there are flowers next year.
4. Improve garden soil by adding organic matter such as compost or worm castings.
5. Clean up groundcovers by lightly raking or mowing over the tops with the mower at its highest setting.
6. Perennials are best divided in two seasons:  very early spring (now) when they are just breaking dormancy or late summer after they have stopped flowering. This is especially true for hostas.  Move or divide before the leaves unfurl.
7. Adding organic matter (compost) to soil before planting ensures a successful garden.
8. Crabgrass will germinate when soil temp (not air temp) is 50 degrees for 3 consecutive days.
9. Remove infected leaves/foliage from iris and from under roses.
10. Sweet corn types:
                 Su:  normal varieties.  Sugars convert to starch rapidly, thus use quickly
                 Se:  increase tenderness and sweetness
                 Se = sh2:  quality and flavor is amazing
11. April 22 is Earth Day! Celebrate and reflect on the fact that it is our responsibility to preserve the natural wonders and resources of this planet so that we may be proud of the planet we leave our children and grandchildren.  
           

Lawn

1. Using the right fertilizer at the right time not only maximizes turf performance , it also saves money.
2. Most fertilizer applications to the turf focus on nitrogen (N), phosphoros (P), and potassium (K).

            Nitrogen will promote leaf growth and deep green color.
            Phosphorus aids seed germination and seedling establishment.
            Potassium aids tolerance to stress, such as traffic and heat.

1. Sweep or blow grass clippings back onto the lawn.  Don’t waste the free nitrogen.
2. Always sweep or blow fertilizer and herbicide pellets back onto the lawn so that it does not go down the storm sewer and harm local water quality.
3. Passing cars and snow plows can spray or throw road salt onto plants, damaging roots and browning leaves.  When weather warms, hose off affected plants and soak the soil to dilute salt buildup.
4. Turf pre-emergent should be put down WITHOUT fertilizer.  This is not the time to speed up grass growth, unless you actually enjoy mowing every three days!  Apply pre-emergent at the end of April to the 1st of May.  A second application can be put down in June, if necessary.  While the big box stores do not normally carry pre-emergent without fertilizer, it is generally available at hardware stores in the Omaha metro area.  One you can ask for is Weed Beater Complete by Bonide. It controls grassy and broadleaf leaves.
5. If you dormant seeded, hold back on watering during the present cold temps to control damping off disease.
6. While the best time to seed is in the fall, some situations require spring seeding.
   a.  It is important to purchase high quality seed from a reputable dealer and seed at the recommended rate for the species.

          b.  An excessive seeding rate will actually delay establishment and thus increase weed pressure—so more is not better!
          c.  Fertilize cool season lawns with 0.75 to 1.0 lb. per 1000 square feet of slow release nitrogen.
          d.  Mulching grass and allowing the clippings to fall on the lawn DOES NOT increase thatch.  Let them fall.  That is free nitrogen.
 
     Crabgrass Control
     a.  Do not be in a rush to apply pre-emergent control for crabgrass.
     *freezing temps will likely kill crabgrass seedlings that emerge before April 15
     *make your application between April 15 and the first week of May
     *apply your control when soil temps at 1” depth is 55 degrees for at least 5                days.
     b.  Go to http://gretnawx.net to get weather related information, including soil     temps.
     *control products for crabgrass containing prodiamine or pendimethalin will
       work if crabgrass is at one leaf stage and if it is watered in immediately.
 
     Aeration
     a.  Hold off on aeration until the grass is growing vigorously.
     b.  How often should you aerate your lawn?
         *Twice a year if you have heavy clay soil and heavy foot traffic
         *Once a year if you have well-drained soil and little foot traffic
     c. Remove soil cores, ¾” in diameter and 3” long.  Should end up with 20 to 40
         holes per square foot.  
     d.  Aeration (when it is done correctly) relieves soil compaction, improves water and nutrient movement in the soil and prevents thatch accumulation.
               Having someone go over your yard once is doing no good at all.
 
 
 Trees & Shrubs

1. Spray crabapple and apple trees for apple scab when leaf buds open. See G1922 at extensionpubs.unl.edu/ 
   
2. For pine diseases, spray when candles are ½” long.
   
3. Unlike some flowering trees, the serviceberry is a native plant so it can handle the cold.
   
4. Frost cracks on trees will seal over on thin bark.
   
5. Plan on pruning spring flowering shrubs AFTER they bloom to promote good flowering next year.
   
6. Thinking of pruning your trees this year?  A tree is an investment.  If you respect that investment, then call an arborist.  And never allow anyone to “top” a tree.”  This is just paying for vandalism.  If you call an arborist, as you this will never be an issue.  The sprouts that come on a tree after it is topped are weak and will easily break.
   
7. Keep mulch several inches away from the trunk of a tree.
   
8. When temperatures are above 40 degrees and before buds break, apply a Dormant Oil to your trees and shrubs to kill overwintering insects and
   
9. scale. 
   
10. New Emerald Ash Borer website:  https://nfs.unl.edu/nebraska-eab  
    
11. New research shows the optimum time to prune living branches is in late spring and early summer because pruning at this time promotes the sealing of the pruning wounds. 

 
Pesticides

1. The label on a pesticide is actually a legal contract for manufacturers to tell you how to use the product.  
2. Reading the label is your first move to keep yourself and the environment safe.
3. Signal Word—“Danger” means exposure to even small amounts of the concentrate or spray can make you sick or cause burning irritation to eyes and skin.  It is important to wear goggles and long pants, long sleeves, and closed-toe shoes when spraying.  Exposed skin and the eyes are the easiest way chemicals enter the body.  
4. NEVER use more concentrate than the directions on the label indicate.  More is not better; it is just more dangerous.  
5. A pesticide may not be effective if it has been frozen or become too hot.  
6. Neonicotinoids are systemic chemicals that are absorbed into a plant’s vascular system, leaving the entire plant toxic and thus harmful to bees. This is especially prevalent at certain big box stores.  Check the plant label before you buy. 
   
7. Timing is the key to specific insect control.   When applying pesticides, contact the Extension Service if you have questions.