Can You HydroSeed Over an Existing Lawn?

Existing lawn buried with topsoil.

All plants, including grass plants, need adequate soil space for roots to spread and develop. Grass seed should always have good soil contact to establish properly. We do not recommend burying a patchy lawn with more soil unless it is very thin without removing the old grass first. If we hydroseed over your old lawn, the new grass roots will compete with the root space already occupied by the old lawn underneath. Your new lawn will be competing for soil nutrients, and water if the old lawn survives. If your old lawn is buried deep enough it will start to decompose causing excessive heat to the new roots which will cause your new lawn to suffer and die quickly. Your hydroseeded lawn will look great initially but will eventually thin out by disease and eventually you will be replacing your lawn once again.

Lawn turning yellow

I wanted to post these pictures for awareness. Please share if you think it will help someone else.

We received an email from a client that we hydroseeded 6 weeks ago with concerns of much of the lawn being light green and sparse. Our client stated they wished the entire lawn looked like the dark green thick patch in the picture.

When we hydroseed a lawn we always leave a care guide with our customers. We tell everyone if they follow our guide they will have an outstanding lawn. I have tried to compile almost 20 years of experience on 2 pages for what I know works best. But for some reason 1 particular paragraph(*) often gets overlooked resulting in this concern.

(*)FERTILIZING: In 3-4 weeks your lawn will need to be fertilized using a high nitrogen or “Turf Builder”
fertilizer. This must be applied by the end of the 4th week to maintain a dark green appearance and promote a thick lush lawn. We used a high phosphorus “starter fertilizer” when we hydro seeded. Phosphorus stimulates healthy root development in the early stages. It is not necessary or beneficial to use a starter fertilizer again. If your lawn looks thin, not ready to mow and turning yellow this is a good indicator that
your lawn needs nitrogen. We recommend using a premium grade slow release fertilizer with nitrogen being the highest number on the bag.

In these pictures the dark green spot was most likely a 🐕 who wanted to put some urea on the lawn. I explained to my client if the lawn was fertilized 2 weeks ago the entire lawn would look like that dark green spot. I have to say they did a great job with the watering showing nice uniformity.

If you use a lawn care company you need to notify them the day we hydroseed that your lawn will require a turf building or high nitrogen fertilizer in 3-4 weeks. This will give them time to work you into their schedule.

There is no harm done here, once the lawn gets fertilized and watered in it will quickly start to look like the dark green patch.

Too much grass seed and your lawn may struggle.

More is not always better and this is especially true when it comes to planting grass seed. I will talk more about the impacts later but first I want to explain how our hydroseed application is calibrated.


The First thing anyone would notice about hydro seed is the attractive green appearance. It not only looks nice but it is really a visual aid to the applicator. Once the hydroseed hits the ground it starts forming an even layer of (green) wood fiber, grass seed, fertilizer, tacking agent to bond the mixture to the soil. Always Green also offers many other additives including weed control that is now included in every application, growth stimulants, lime, moisture retainers, insect and disease controls. Every product we add to the hydro seed slurry is carefully measured in accordance with the label. The applicator must have the correct training and licensing and carry additional insurance to apply these products. At this time the only person applying the hydro seed is the owner who founded Always Green Hydroseeding back in 2004. I can assure you with over 15 years of experience I know what the finished product should look like on your soil.

So lets talk more about the grass seed. This is obviously the most important ingredient in the hydro seed slurry. Without the grass seed there will be no lawn. This is the one thing I put a lot of time and research into. Every winter I work closely with my seed supplier choosing some of the best varieties of grass that gets the highest ratings on the NTEP trials. You can Learn More about the varieties of our grass seed. We use the latest lateral spread technology that fills in and repairs bare spots and thickens up a thin lawn. It is crucial we use the correct amount of grass seed so the lawn can fill in properly. Too much grass seed causes undue competition for resources such as light, water and nutrients, and grass seedlings struggle and may even dampen off as a result.

Each type of grass seed variety we use (Turf Type Tall Fescue, Perennial Rye and Kentucky Bluegrass) germinate about a week apart. So your lawn will start off thin then gradually get thicker as all the seeds germinate usually within 3-4 weeks. Temperature and proper watering also are key factors. We sometimes get calls within the first 30 days with concerns about thin and bare spots. Unless you had an obvious wash out from an excessive amount of water from run off it is likely you have seed that has not germinated yet. If you can still see the wood fiber that is now likely a tan color there should still be plenty of seed mixed in. If you once had grass sprouting and now looks like dirt again that may be a fungus that melted out the lawn which may appear the same.

Unless you know for sure you did not have a wash out or get a disease it is not advisable to add any new seed until the following season. This will give seed a chance to still germinate that may be behind from not enough irrigation. Areas in full sun will need more water than shaded areas. Keeping your seeds moist in the full sun is the key to success. If you let your seeds dry out during the day while exposed to the sun will certainly add days even weeks on to the germination cycle.

We want to assure you we use the correct amount of grass seed applied evenly and consistently to give you turf quality results. Nobody is going to get a re spray under our 30 day guarantee unless it is proven by our seed reps that the seed was unviable. Since we have 10,000 pounds of grass seed blended exclusively for our company at one time it would quickly become evident that we have a big problem. We encourage our customers to be home to see that the hydro seed was applied evenly. We will even provide you with our certified seed label from the bag of seed upon request.

At this time we are not retailing our exclusive grass seed but if you need to do any repairs or over seeding look for Jonathan Green Black Beauty Ultra. This is also a high quality seed that will match best with similar varieties.

Fall is not the best time to seed a lawn in Rhode Island.

So you are probably wondering when is the best time. The absolute best time to plant any kind of turf grass seed in Rhode Island is in late summer between August 15th and October 1st. This time frame only includes about a week into Autumn. Late Summer is the best time to plant a lawn, here’s why.

Every year we see valuable time wasted in the prime growing season due to the misconception that you have all fall to plant. The reality is once the soil temperature drops below 50 degrees germination will come to an end. This may occur any time after the middle of October. Then you will also be dealing with leaves covering your new grass plants which can also be a challenge.

Always Green does not recommend seeding from the middle of June to the middle of August. Seed at your own risk in the Summer, here’s why. Although it is possible and we will seed your lawn during this time it may be more costly for the proper treatments for success.

With newer advancements in weed control Spring should not be overlooked as a good time to plant as well. Always Green does more hydroseeding in Spring than any other time. How we control weeds in the spring is the key to our success to establish a lush weed free lawn before summer.

Cool wet start delays Hydroseeding

As May is upon us you would think that we were busy all of April installing new lawns. Well the fact is we were only able to install 3 using topsoil. Our projected goal was to have 8 renovations completed. Due to the 21 out of 28 days of rain in April it was beginning to get very difficult to find topsoil that was not mud. It not only is very heavy, it is very difficult to spread and get all the lumps out. At the source is very difficult to screen when wet causing a shortage and to eventually sell out by the end of April.

We always stay busy servicing other customers hydroseeding needs. Even less calls from homeowners and landscapers. It is a trickle down effect, if we can’t get dry topsoil, nobody can. This lead to a decrease in phone calls for any hydroseeding. We hope May will bring warmer drier weather so we can complete some renovations by June 15th. If it goes beyond this date customers are strongly advised to wait until after August15th when the nights get cooler. This is the most ideal time to seed.

Challenges of Hydroseeding under trees.

2014-05-14 09.54.27

We have no problem dragging our hose anywhere we need to go to get hydro seed where it needs to be. But there are some areas where grass just does not belong. You would not want to grow a lawn under your deck right? Not only would it be very difficult to mow but it would never get the sunlight it needs to survive. As a rule of thumb for growing a lawn if the lawn is not getting at least 3-4 hours of filtered sunlight it may be a better option to consider a better shade tolerant ground cover.

Always Green uses grass varieties that do very well in both sun and shade. We always tell our customers that our hydro seed will grow just fine in shadier areas but over time it will thin out if there is not enough sunlight. Areas that stay wet and not dry out will start to grow moss and may become more dominant than the lawn.  The only way to correct this is to thin out the trees to let more light through. Not only are there challenges with light but there is also many tree roots under ground competing with the grass roots. Your tree roots are stealing the moisture and nutrients that your lawn needs. Not only that but sometimes if it does not rain heavy enough the raindrops get caught in the canopy of the trees and never make it to the ground. Since a shaded lawn does not photosynthesize as a lawn in full sun it is not using as many nutrients so your tress are getting fed more. You can actually over feed a lawn in the shade as it can’t utilize the nutrients as quickly.

During the establishment phase there is a higher risk of erosion under trees. We use enough tacking agent to keep the hydro seed in place without washing away under most extreme rainfall conditions. Anytime you take on additional water running off flat surfaces, downspouts and water shed off of trees all bets are off. There is really no problem with a heavy rain drops falling straight down on a hydro seeded area with little to no problems. Once the rain gets collected in a tree canopy the raindrop size changes to much larger drops and come down at a more forceful rate causing certain erosion leading to spotty results. When this happens re-seeding will most likely be needed.

So if your going to hydro seed around a tree canopy make sure your getting enough sunlight for the lawn to survive. Moss is usually a good indicator there is not enough light. Have your soil pH tested, ideally it should be right around 6.5 ideally. Thin out the trees as much as possible to let more light through. Plan on over seeding  yearly with a shade tolerant seed. Be sure your lawn is getting the right amount of water using rain gauges and do not over fertilize. Understand the potential of erosion if the lawn does not get established before torrential rains.



2018 Spring Update

As of April 15th temperatures still struggle to climb for optimal germination. We have started hydro seeding with a reminder to our customers to be patient with slow germination due to the cool soil temps.
At this time we have not started any lawn renovations or new lawn construction due to inclement weather and the availability of dry topsoil. We are hoping the second half of April conditions will improve so we can get some work done. For the first half of April we have been spraying new lawns for customers that have had new septic systems installed and projects where suitable soil was prepared for us.
Always Green is a Hydro Seeding Specialist which means we only install new lawns. 90% of our work is applying hydro seed to your bare soil that was prepared by you or another contractor. 10% of our work is full lawn renovations or new lawn construction.
At this time we are only offering hydro seeding for your prepared soil. We are fully booked up this spring for the small percentage of renovation and new lawn construction work we offer.
Always Green is owner operated and our priority is to be available within a 1-3 day notice to deliver and apply hydro seed to your prepared site. You would prepare your site the same way as if you were rolling out sod with special attention to the top 1-2″ of soil being soft and loose. You should be able to poke your index finger in the soil and cover your first knuckle with ease. This will assure good seed too soil contact and an even application.
Another common question we need to clarify is (our hydro seed) needs to be applied to bare soil. It is not good practice to apply hydroseed on top of an existing lawn unless it is very sparse and there will still be good seed to soil contact.
Please call if you have any questions. I return most calls by the same evening except on holidays weekends.

Spring Soil Temperatures

With the warmer weather this February we may have an early start this spring. Hydro seeding may begin as early as the middle of March.

We ask our customers to be patient with germination in the spring while the soil temperature come back up into the 50’s. Grass seed needs soil temperature to be at least 50° for germination to start. Here is a soil temperature map for our region.

Get a free estimate now for a spring hydro seed application.