Question

  Hello,
  I live in the high desert of Nevada. The soil here is basically sand and is alkaline. It is well drained.
  I've planted green ash,lacebark elm,siberian elm as a windbreak,quaking aspen,cottonwoods,poplars.golden rain trees.and am going to plant sargent cherry,kwanzan cherry,and flowering crabapple I've also planted wild wood rose,sand cherry,american elder,lilac,siberian pea shrub.
 So far everything is growing and establishing well.The key in this area is that everything gets plenty of water.Probably considered overwatering in other areas of the country.The soil does not have a lot of nutrients.Is there something you would recommend as a good overall fertilizer for this group that wouldn't cost me an arm and a leg? By next year I will have about 150 plantings. About 50/50 shrubs and trees.My lilacs are suffering from the heat and wind at the moment. I'm thinking about moving them to a more protected area. I live in a high wind area.Hot and dry here.Stressful to both shrubs and trees. Thanks for any info you can provide.
Regards.
Craig  

Answer
Most trees should be fertilized but in most suburban locations trees do not need extra fertilizer as they get plenty from lawns, etc.

However, you can keep your eyes out for nutrient deficiencies such as pale green leaves, reduced leaf sizes, yellowing along the leaf veins, overall reduced growth and vigor, and  premature fall coloration

If you decide to fertilize newly planted trees or shrubs then start by fertilizing annually for 2 years and then switch to fertilizing every 2nd year until the tree or shrub matures (depends on the actual tree/shrub in question).

If trees/shrubs grow in lawns or flower beds which are already fertilized then cut back accordingly, and only fertilize mature trees and shrubs if growth seems inadequate.

I recommend that you buy a complete fertilizer which is one which has about equal amounts of nitrogen-phosphorous-potassium, such as 10-10-10. For best result try to buy one with maximum amount of nitrogen in a slow release form (e.g. WIN = water insoluble nitrogen). The lable usually states how much.

You can look out for names such as The nitrogen sulfur-coated, IBDU or urea-formaldehyde. These are indications that the nitrogen is in slow-release form. The bags should state how much nitrogen is slow release.

A 10-10-10 fertilizer will have 10% nitrogen (the first number of the 3). If a bag states that 2% of the nitrogen
is water insoluble ("WIN"), this means that 20% (2 / 10) is in slow release form.

Your goal is 50% or more of the nitrogen in slow release form (e.g 5% of the 10% nitrogen. read lables on bags).

Another example, if you buy a bag of 16-18-20 fertilizer. This means that the bag contain 16% nitrogen. if the bag contains 8% or more of water insoluble nitrogen then you are ok (more than half of the nitrogen is slow release).

You may have to check around to find the right product with the combination of balanced fertilizer and slow release nitrogen. Generally 10-10-10 is not expensive, but do check the slow release properties.

For both shrubs and trees you can use below calculations:

Use about 2 lbs of nitrogen per 1000 sq feet spread evenly over the entire root zone. To calculate the root zone meassure from the trunk until the edge of the overhang of the branches (the radius). Then calculate the area as:
Area = 3.14 x (2 x radius) x (2 x radius).

Example, if the branches hang about 10 feet out from the tree on each side you would calculate the area as:

3.14 x (2 x 10) x (2 x 10) = 1,256 sq feet.

Then use 1.256 x 2 lbs = 2.5 lbs fertilizer.

Spread the fertilizer evenly in a circle under the canopy of the tree (branch outreach).

Water well after spreading fertilizer

Before fertilizing your trees, however, it may help to have a soil test done.

Especially with small shrubs be very careful not using too much fertilizer. Younger shrubs and trees need to be fertilized whereas mature trees and shrubs generally needs less help.

Note that some plants prefer an acidic soil to grow well. Lilacs prefer soil pH between 6 and 7. If yours is much above this then it may need to be reduced using gardeners sulphur. Lilacs also prefer a humus rich organic soil. You may consider adding liberal amounts of compost and peatmoss sphagnum in the planting hole if you are transplanting. (Peatmoss sphagnum is excellent to reduce soil pH also as it is naturally very low).