Spring Lawn Care in Sonoma, CA: What to Do and When to Do It
By Scott Anderson Landscaping · Serving Sonoma County homeowners
Sonoma's mild Mediterranean climate gives local lawns a head start come spring — but it also means weeds, dry spells, and soil stress arrive early. Here's your step-by-step guide to spring lawn care in Sonoma County.
1. Know your Sonoma soil before you start
Sonoma County soils vary widely — from the clay-heavy valley floors to the sandier hillside properties. Before doing anything else, check that your soil is ready to work. The squeeze test is simple: grab a handful, squeeze it, and open your hand. If it crumbles, you're clear. If it holds a ball shape, wait a few more days.
Cool-season grasses like fescue — common throughout Sonoma — start growing actively when soil temperatures hit 50°F. A soil thermometer takes the guesswork out of timing, and it's worth the few dollars for the accuracy.
2. Rake out winter debris and dead grass
Even in Sonoma's relatively mild winters, thatch and matted grass build up and block sunlight and airflow from reaching your soil. A thorough spring raking — with a flexible lawn rake, not a leaf rake — in multiple directions will lift that mat and reveal what you're working with.
Note any thin or bare patches as you go. These areas are candidates for overseeding later in the season.
PRO TIP FROM OUR SONOMA TEAM
If your thatch layer is thicker than half an inch, raking alone won't cut it. Power dethatching or core aeration is often the better move — especially for older Sonoma County lawns that see heavy foot traffic or clay soil compaction.
3. Aerate to fight Sonoma's clay compaction
Clay soils — common throughout Sonoma's valley areas — compact easily over winter. Core aeration removes small plugs of soil across your lawn, opening up pathways for air, water, and nutrients to reach the root zone where they're needed most.
Spring is the right time to aerate cool-season lawns in Sonoma County. If water is pooling on the surface or your lawn has thinned out despite regular maintenance, compaction is likely the culprit.
4. Apply pre-emergent weed control at the right time
Sonoma's warm spring temperatures mean weeds like crabgrass, clover, and annual bluegrass wake up fast. A pre-emergent herbicide stops weed seeds before they sprout — but timing is critical. Apply when soil temperatures are consistently between 50–55°F, typically in late February to early March in Sonoma.
Planning to overseed bare patches? Use a pre-emergent labeled safe for new seed, or hold off until after your overseeding window has closed.
5. Fertilize smart — not heavy
Spring fertilizing gives your Sonoma lawn the nitrogen it needs to green up after winter dormancy. But going too heavy too early pushes rapid top growth at the expense of deep root development — which is the last thing you want heading into Sonoma's dry summer months.
A slow-release granular fertilizer applied in mid-spring, once the grass is actively growing, tends to produce the most durable results. A soil test — available through the UC Cooperative Extension in Santa Rosa — will tell you exactly what your lawn needs before you spend a dollar on product.
6. Set your mower height for Sonoma's spring conditions
As you start mowing again in spring, keep the blades higher than you might in summer. Taller grass shades the soil, retains moisture, and naturally suppresses weed germination — all valuable in Sonoma's increasingly warm and dry spring conditions. The one-third rule applies year-round: never cut more than one-third of the blade height in a single mow.
Before your first mow of the season, sharpen your mower blades. Dull blades shred the grass tips rather than cutting cleanly, leaving your lawn more vulnerable to disease — a real concern in Sonoma's humid spring mornings.