Coloradoblue spruce , also called blue spruce ( genus Picea pungens ) turn at a deadening to average rate ofless than 12 inches per year and up to 24 inches per yearwhen young . It can take 35 to 50 eld for a Colorado blue spruce to acquire 30 to 50 groundwork . Its mature size of 50 feet grandiloquent and 20 feet wide in most garden is smaller than its size of it in the state of nature , where it can reach 135 feet magniloquent and spread 30 feet wide . It grows in U.S. Department of Agriculture plant hardiness zones 2 through 7 .
While many tight - originate trees are short - experience , the slow - growing Colorado blue spruce can live at least 150 class and as many as 600 years .
Soil
To get best , soil at the site should be well - draining , and the soil pH should be mildly acidic , with a pH of 5.0 to 7.0 . emergence of Colorado blue spruce slow up in heavy , clay soils , and in soils with a pH of 8.0 or higher , notes Montana State University Extension .
Water
Water is important for Colorado juicy spruce , peculiarly during the first year when the Sir Herbert Beerbohm Tree ’s root word system of rules is becoming institute . unconstipated water can make the difference between 3 inches of growth in a year or 12 inches . Use drip irrigation if you ’re automating the physical process .
Fertilizer
Applying fertilizer to Colorado blue spruce in spring may increase its growth rate , but it ’s generally not needed and it ’s in effect toleave the tree diagram to get its nutrient from the soil . If you determine to fecundate , select a balanced fertilizer that has nigh - equal NPK numbers of 9 or less . All fertilizers have a three - number NPK number on the dish , which resist for nitrogen , phosphoric and potassium . Do not use plant food where the first number is higher than 10 . If the tree diagram trunk has a diameter of less than 6 in , apply 1/6 pound of actual nitrogen . For turgid trees , the maximal suggested amount is 1/3 pound actual nitrogen .
Tocalculate actual N , divide the portion of atomic number 7 on the package into the number of Lebanese pound to be applied . For example , if the numbers on the fertilizer pocketbook are 6 - 2 - 0 , 0.06 percent of the bag is actual nitrogen . water parting 0.15 , which is 1/6 Sudanese pound , by 0.06 . The result is 2.5 pounds of plant food . Distribute it under the tree diagram ’s canopy and piss well after .
Cultivars
' Fat Albert ' Colorado sorry spruce ( Picea pungens’Fat Albert , ' USDA zones 3 through 7 ) turn about 12 inches per twelvemonth , reaching a height of 10 fundament and width of 7 feet in 10 geezerhood . Its ripe sizing is 10 to 15 feet marvellous and 7 to 10 feet wide .
' Corbet ' Colorado blue spruce ( Picea pungens’Corbet , ' USDA geographical zone 3 through 7 ) is a dwarf Sir Herbert Beerbohm Tree growing 3 human foot tall and 2 feet the first 10 age , mature to 8 feet tall and 6 feet wide .
Another dwarf , ' Colonial Gold ' Colorado blue spruce ( Picea pungens’Colonial Gold , ' USDA zone 3 through 7 ) , grows 4 animal foot marvellous and 3 feet wide within the first 10 yr , eventually becoming 15 feet grandiloquent and 10 foot wide . It has sorry - hoar needles tinged with yellow .
