Hydroseeding in Philadelphia, PA

Hydroseeding in Philadelphia is how we put grass on ground that has just been graded, dug up or stripped bare: new construction lots, rebuilt back yards, regraded side slopes and the raw strips left after utility and drainage work. We mix seed, wood fiber mulch, starter fertilizer, tackifier and water in one tank and spray it onto a prepared seedbed, so the seed lands already covered and held in place. We work across the city and the suburbs in Bucks, Montgomery, Chester and Delaware counties and nearby South Jersey, on everything from a narrow rowhouse yard to several acres of builder's ground.

Two kinds of ground meet here

Philadelphia sits on the Atlantic Seaboard Fall Line, the boundary between the hilly Piedmont and the flat Atlantic Plain. That line shows up in the dirt. Northwest of it, on the uplands toward Chestnut Hill, Montgomery County and Chester County, soils like the Chester series weather from micaceous schist. The USDA describes them as well drained, with a silt loam or loam surface over a silt loam to silty clay loam subsoil that turns yellowish red as you dig down. Slopes on those soils range from nearly flat to 65 percent. Southeast of the Fall Line, along the Delaware River and across into Camden and Burlington counties, the ground gets sandier and flatter. Sandy soil drains fast and dries out a seedbed in a day; silty Piedmont soil holds water but crusts and washes on a slope. We adjust mulch rate, seed mix and watering advice to the side of the line your yard is on.

Weather that shapes the seeding calendar

The city's climate is on the northern edge of humid subtropical. Average precipitation is about 44.1 inches a year, January averages 33.7 degrees and July about 78.7, and highs reach 90 or more on about 30 days a year. The average freeze window runs from November 6 to April 2, a growing season of about 217 days. Lawns here are cool-season grasses: turf-type tall fescue, Kentucky bluegrass, perennial ryegrass and the fine fescues for shade. Penn State Extension says the optimum times to seed turf in Pennsylvania are mid to late spring and late summer to early fall, and that late summer is the strongest window because late August and early September soils are warm and dry enough to work, and seedlings get both fall and spring to root before their first summer. Summer seedings face heat, drought and disease, and seed will not germinate once soil turns cold in late fall.

So our busiest stretch is mid-August into early October. Spring work is fine, especially for construction sites that cannot wait, but a spring lawn has to be watered harder through its first July.

Hydroseed, sod or dry seed

There are three ways to get grass on bare ground, and each has a place.

• Sod gives you a finished lawn the day it goes down and can be laid almost any time the ground is not frozen. Penn State calls it usually the most expensive way to establish cool-season grass, and Kentucky bluegrass is the common sod species in Pennsylvania, which is not the right grass for heavy shade. Installed sod, by HomeGuide's numbers, costs $1 to $4 per sq ft.
• Dry seed with straw is the cheapest route on a small, flat patch. Straw is the most widely used and least expensive lawn mulch, but it blows around, brings some weed seed and has to be spread at the right rate.
• Hydroseed sits between them. The University of Nebraska Extension puts its price slightly above dry seeding and, as a rule, below sodding, and says hydroseeded grass generally becomes visible in 5 to 7 days, where dry-sown seed takes two to three weeks. HomeGuide lists hydroseeding at $0.12 to $0.35 per sq ft. Penn State notes it is most efficient on large areas and steep slopes, which is where it earns its keep around here.

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Stormwater rules in the city

Parts of Philadelphia are served by combined sewers, where rain and sewage share the same pipes, and the Water Department's rules aim to keep sediment out of them. Its stormwater manual says all earth disturbance must meet Pennsylvania DEP erosion and sediment control requirements, that projects with 5,000 square feet or more of disturbance must submit an Erosion and Sediment Control Plan, and that every project, regardless of size, must install controls suited to the site. City-owned inlets that take runoff from a work site must be protected, and silt fence must be trenched in and backfilled to work. State rules then decide when a site is finished: 25 Pa. Code 102.22 counts ground as permanently stabilized only when it has a uniform 70 percent perennial vegetative cover or another approved practice, and it requires seeding or mulching right away when work stops for more than 4 days. That is why builders and site contractors call hydroseeding contractors at the end of a job: the grass is what lets the silt fence come down.

Topsoil and grade come first

Most failed lawns we see were seeded on the wrong base. Penn State recommends a minimum of 4 to 6 inches of good topsoil, firmed or settled, and a finished grade that falls 1 to 4 percent away from the house. Construction subsoil is usually compacted and needs ripping or tilling before topsoil goes back. A soil test, taken three to four weeks ahead, tells you how much lime and fertilizer the ground needs. We can handle the yard grading, topsoil and dirt work ourselves, or seed behind your excavator once the grade is set.

Slopes, creek banks and wooded lots

The region is full of creek valleys: the Wissahickon, Pennypack and Cobbs creeks inside the city, and the Neshaminy, Perkiomen and Brandywine systems in the suburbs. Fairmount Park and the Wissahickon Valley Park together cover more than 4,000 acres. Homes that back onto those valleys come with steep banks, shade and runoff from uphill neighbors. A light lawn mix will not hold there. We raise the hydromulch rate, add tackifier, use erosion control blankets on the steepest pitches and pick shade-tolerant fescues where tree cover is heavy.

What happens after we spray

The first 4 to 8 weeks decide whether a new lawn makes it, and Penn State says more seedings fail from poor follow-up care than from anything else. Expect light, frequent watering so the surface stays moist, first germination in about a week in warm soil, and a first mow once the grass reaches about 4 inches, roughly six weeks out according to Angi. Keep foot traffic, dogs and equipment off it. We leave written instructions and answer questions by phone while it fills in.

We work in Philadelphia neighborhoods from Chestnut Hill to the river wards, and across four Pennsylvania counties and South Jersey. In Bucks County that means Doylestown, Warrington, Warminster, Northampton Township, Newtown, Lower Makefield, Bensalem and Levittown, where creeks like the Neshaminy shape drainage and the 1950s Levittown lots sit low and flat. In Montgomery County we cover Horsham, Lansdale, Montgomery Township, Whitpain, Upper Dublin, Upper Merion and Upper Providence, a mix of Piedmont hills, shale soils and fast-growing subdivisions. Chester County work takes us to West Chester, Downingtown and Phoenixville along the Brandywine and French Creek valleys, and Delaware County to Newtown Square and Concord Township. Across the bridges we seed in Cherry Hill and Evesham Township, where coastal plain sand drains very differently from the hills west of the city. Each town page explains what changes there.