Knowledgebase

Best soil temp and time for first fertilizer of the year #894601

Asked March 17, 2025, 9:34 AM EDT

Greetings. I live in one of the newer developments in the Parker area where they took all the good dirt from the top and left that garbage clay and then sodded w/ Kentucky Blue. This is the yard's 6th season. * I have received somewhat contradictory input regarding when to do the first fertilization of the year and what to use. I have heard one "professional" say to use a balanced blend while another says I should use high nitrogen for the first application. One recommends synthetic blends to kickstart the growth and awakening while another strongly advocates all organic to wake up slower and build a stronger root system below the "soil". They all seem to agree on achieving a soil temp of about 50 deg. before doing anything. *The back yard isn't bad but the front yard gets full exposure w/ no relief from the sun until it sets behind the single story houses on the other side of the road from us. Last season was merciless. What is the recommended mow height, water frequency and amount for my Kentucky Blue as I'm having a hard time finding a balance? My most recent cycle was 3x/wk, 2x/day early morning and dusk at about 1 1/4" per week. Again, varying input from the "professionals". Thanks for your time. I appreciate any help you can provide.

Douglas County Colorado

Expert Response

Hi Kevin,

Sorry for the delay in getting back to you. 

Under most circumstances, the first fertilization on a Kentucky bluegrass lawn along the Front Range is in March or April, as the grass really starts to green up.  1/2lb of nitrogen per 1,000 square feet of lawn is recommended--you can use whatever formulation you like--what is most important is to get the lawn nitrogen--other nutrients are typically adequate in the soil for lawns (even in "bad" soil).  Returning your clippings to the lawn will help lower your fertilization needs as well.

Lawns in newer neighborhoods are often fighting soil compaction, using a core aerifier machine to aerate will help--aerate so that the holes are on 2-3" centers (more than one pass with the machine).

Taller mowing heights will typically reduce both weed pressure and watering needs because the longer grass can develop more vigorous, deep roots.  3-4" is common; you can go as low as 2.5" if you have a particular need for shorter grass.  
  

This CSU fact sheet summarizes general lawn care information and may be useful for you: https://extension.colostate.edu/topic-areas/yard-garden/lawn-care-7-202/

It includes both watering and fertilizer recommendations, as well as some other general care information.


I hope this is helpful!

Cordially,

John


An Ask Extension Expert Replied March 24, 2025, 12:48 PM EDT

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