You’ve just spent a lot of money—and likely a great deal of time and physical energy—sodding your lawn, and you want to do everything in your power to ensure success. No one likes to see their time and money wasted!
One area you should give new sod extra attention to is fertilizer applications. Proper fertilization of your new sod can make all the difference between a sun-patched, scraggly-looking lawn and a thriving, beautiful, verdant lawn.
When fertilizing new sod, you want to wait until the root system has been established and grown down into the topsoil before feeding it with a specially-formulated started fertilizer. Fertilizing too soon is unnecessary and wasteful since the sod can’t access it.
Basics About New Sod
Laying sod is a much quicker way to start a new lawn (or redo a lackluster lawn) than seeding.
Sod farms grow fields and fields of well-cared-for turf. Long sections of this grass are cut into strips and rolled up into manageable sections. These strips are held together by a short, dense root system and a thin layer of soil and other organic material.
After purchasing rolls of sod, you unroll them across your previously-prepped, bare topsoil for an instantly green, mature-looking turf.
What happens with the roots?
Sod grown on a farm has a shorter and denser root system than established turf grown for years in a backyard. Once this farm-grown turf matures, a special harvester cuts slightly underneath the root system, lifting it off the ground like long narrow rolls of carpet.
When you lay sod on your prepped soil, a thin layer of soil at the base of the sod is directly touching the soil in your yard. The roots are barely touching the ground, if at all.
After being laid, the sods need time for their roots to grow down into the soil, anchoring the rolls to the ground and allowing the plants to access soil nutrients and water.
How much time does it need to get established?
Establishing takes place in two different phases. After laying new sod, it develops shallow roots down into the soil within 10 to 14 days. It takes the sod’s roots approximately 4 to 6 weeks to grow deeper, creating a strong, robust root system.
What does new sod need to succeed?
New sod needs the same as every other plant to grow: sunshine, water, and nutrients from the soil. But caring for it as the roots establish does require a little extra attention compared to mature turf. The sod’s nutrient needs are a little different than established turf—at this stage, you want to promote root growth instead of shoot or blade growth.
This is why correct fertilization (and let’s not forget about watering) is essential.
What do you need to avoid with new sod?
The keys to growing new sod are to avoid damaging the newly establishing roots and minimize external stressors that inhibit growth. When plants are stressed, not only will their growth slow, but it also makes them more susceptible to problems with weeds, insect pests, and diseases.
- Avoid walking or running across your new sod.
- Avoid letting your pets out of the new sod as much as possible.
- Avoid overwatering.
- Avoid overfertilizing.
- Wait to mow until the longer roots establish.
Introduction To Fertilizers
Like humans, plants need “food” containing specific components as fuel for their growth. These essential plant nutrients are naturally found in the soil and taken into the plant through their roots to drive the processes inside their cells.
Over time, soil’s nutrient levels decrease or become depleted as they are taken in by plants or leached out of the soil by water movement. Fertilizer supplements the soil’s lost nutrients for optimal plant growth.
What does N-P-K on a fertilizer label mean?
One of the first things spotted on a fertilizer label is the set of three numbers in big letters. These numbers are known as the N-P-K (nitrogen, phosphorus, and potassium) ratio and help give you an idea of the amount of nutrients in the formulation to compare products.
Manufacturers use these three nutrients since they are needed in higher amounts than the rest of the essential plant nutrients.
When looking at a 10-10-10 bag of fertilizer, all three nutrients make up ten parts or 10% of the product weight. So a 10-pound bag of 10-10-10 contains
- One pound of nitrogen.
- One pound of phosphorus (in the form of P2O5).
- One pound of potassium (in the form of K2O).
What Are Starter Fertilizers And How Are They Different Than Regular or Maintenance Fertilizers?
You can broadly group lawn fertilizers into starter fertilizers and regular or maintenance fertilizers.
Starter fertilizers are usually applied to germinating seeds or seedlings to supply necessary nutrients until the root system of the seedling develops and can access them in the soil.
The goal of starter fertilizer is to help to enhance seedling root growth in places where the conditions might not be the most favorable. These conditions could be cold soil temperatures, wet conditions, low pH of the soil, and so on. Enhancing the seedling’s root growth helps them establish successfully.
Regular fertilizers—often known as maintenance fertilizers—are formulated with the nutritional requirements of established lawns in mind. Their goal is to maintain an overall healthy lawn that is lush, green, and strong enough to tolerate environmental stresses and resist insect and disease attacks.
Comparing The Nutrient Differences of Starter and Maintenance Fertilizers
Both types of fertilizer contain all three primary nutrients needed for plant growth. But the amount of nitrogen, phosphorus, and potassium varies since the two types are formulated to address plant needs at different life stages.
- Starter fertilizers contain a higher percentage of phosphorus than the other two elements. The P percentage should be at least 20% higher than nitrogen and potassium. Common ratios range from 1:2:1, to 1:3:1, to 1:4:2, or 1:5:0.
- Regular or maintenance fertilizers usually contain a higher quantity of nitrogen since established lawns need more nitrogen for their growth. Typical ratios for regular lawn fertilizers are 3:1:3 or 4:1:2.
|Starter Fertilizer||Maintenance Fertilizer|
|Goal||Promote Root Growth||Maintain Overall Health|
|Targeted Lifestage||Seed Germination & Seedling||Established, Mature Turf|
|Focused Nutrient||Phosphorus (P)||Nitrogen (N)|
Best Starter Fertilizer For New Sod
What should be included in the formulation?
You want a starter fertilizer with lots of phosphorus, potassium, and carbon. Phosphorus helps with root growth; potassium improves drought tolerance, disease resistance, and cold hardiness; carbon improves the soil’s overall health to create a thriving, growing environment.
Also, look for products with:
- Humic acids to enhance microbial activity, soil texture, and water retention.
- Biostimulants contain plant hormones, enzymes, vitamins, beneficial carbohydrates to enhance nutrient availability, uptake, and use, bolster microbial colonies, and improve soil structure.
- Other macro and micro-nutrients needed for growth such as calcium, magnesium, iron, zinc, and manganese.
What ingredients should be avoided?
- Too many synthetic components that can damage beneficial soil microbes.
- Too much fast-acting nitrogen such as urea, ammonium nitrate, and ammonium sulfate that can burn roots.
Turf Mechanic Starter Fertilizer Recommendations
See the following post for my full thoughts on the best starter fertilizers you can buy today.
When Do I Fertilize Newly Laid Sod?
Generally, it is recommended that you fertilize new sods approximately four to six weeks after being laid. As discussed earlier in the article, this coincides with establishing deep roots.
This recommendation, however, is a loose guideline. There isn’t a fixed timeline for fertilizing new sods. Consideration must be given to the type of grass used and the time of year you laid it.
The reason for waiting and not applying fertilizer immediately to new sods is to give the root system time to lengthen and grow down into the soil. Roots on new sod aren’t long enough to absorb the nutrients captured by the soil after fertilization. Consistently watering new sod will leach these nutrients out of the soil.
Keep in mind, too, that they regularly fertilized the sod at the sod farm. So fertilizing it immediately after laying it down is a waste of your money and may cause nutrient toxicities.
After the first fertilizer application, wait at least another six to eight weeks before fertilizing a second time.
Q. Can you put starter fertilizer on existing grass?
You can put starter fertilizer on existing grass, but it contains less nitrogen than maintenance fertilizers. It won’t harm it. However, the resulting growth won’t be as robust, and over time, applying starter fertilizer can create an unhealthy lawn.
Q. Should you apply starter fertilizer before laying sod?
No, you shouldn’t apply a starter fertilizer before laying sod for the aforementioned reasons. However, it is beneficial to amend the soil before laying sod with milorganite for nitrogen and phosphorus, sulfate of potash for potassium, azomite for trace minerals, and biochar for water and nutrient retention.
Q. How long until sod lines disappear?
Sod lines typically take four to six weeks to disappear if the soil was prepped correctly and you take good care of the new sods.
Q. How often do you water sod after laying it?
After laying new sods, water them for twenty minutes, twice every day for the first sixty days. It is best to water once in the morning and then again in the evening, avoiding the hottest part of mid-day.
Q. Can you over-water new sod?
Yes, you can over-water new sod. Overwatering hinders root growth and may damage the grassroots, preventing the roots from growing down into the topsoil. Consistently overwatering new sod will lead to rot.
Q. Should you fertilize new sod in spring?
Yes, spring is the best time to put down new sod and apply fertilizer to it. Sod grows best in the rainy, cooler spring season.
Q. Can you overfertilize new sods?
Yes, you can over-fertilize new sods if you schedule fertilizer applications too close together and apply fertilizer without running a soil test beforehand, so you know the soil’s nutrient concentrations.
Q. How do you know if your sod was overfertilized?
Symptoms of over-fertilized sod include yellow or brown grass blade tips, scorched blades, and limp, black roots. Growth may also slow or stop altogether. Another sure sign of over-fertilization is crusting at the soil surface.
Q. How do you remedy overfertilized sod?
Water the new sods thoroughly every day for at least seven days to flush excess fertilizer out of the root zone. Give it three or four days to let the soil dry out, and then continue with your regular watering schedule. If the sod isn’t rebounding, you may need to replace it or reseed it.
Conclusion: Should You Put Fertilizer On New Sod?
Now, let’s revisit the original question—should you put fertilizer on new sod?
The short answer is don’t apply any fertilizer right after laying sod. Give it four to six weeks to develop a healthy, deep root system and then fertilize it with a lawn starter fertilizer formulated with higher potassium levels to enhance root growth.
Once the sod establishes itself and attaches well to the soil underneath, you can switch to a maintenance fertilizer promoting robust, overall growth.