Should I fertilize or grass first?

Deciding whether to fertilize or seed grass first when overseeding or establishing a new lawn is a common dilemma for homeowners. Both fertilizer and grass seed are vital for growing a lush, green lawn, but the order in which you apply them can impact the success of your lawn project. Proper timing and technique are key when fertilizing and seeding to avoid wasting money on products that won’t work.

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Should I Fertilize Before or After Seeding?

When overseeding an existing lawn or establishing a brand new lawn, it’s generally best to seed first and fertilize second. Fertilizer provides nutrients that help new grass plants grow, but it also fuels the growth of existing grass and weeds. If you fertilize before seeding, the existing vegetation may grow too tall and thick, shading and crowding out new grass seedlings. Seeding first allows the new grass to sprout and establish before encouraging growth of existing plants.

However, there are a few scenarios where fertilizing before seeding may work:

If you are starting a brand new lawn from bare ground or scratch, pre-fertilizing is unlikely to cause any issues since no existing plants are present. Fertilizer will help enrich the soil for new seedlings.
When overseeding very thin or bare spots in an existing lawn, fertilizing first may help accelerate growth to fill in the patches. But this risks having existing grass take over the bare areas before new seeds can establish.
Using certain slow-release fertilizers before seeding may provide nutrients to new seedlings without overly stimulating existing growth. But fast-acting synthetic fertilizers should always be applied after seeding instead.

So in most overseeding situations, it’s best to seed first and then fertilize about 4-6 weeks later when the new grass plants are a few inches tall. For new lawns, you may be able to fertilize first or apply starter fertilizer at seeding time since competition from other plants isn’t a concern.

Tips for Seeding Before Fertilizing

Here are some tips for proper timing and techniques when seeding grass before fertilizing:

Mow the existing lawn short, around 1-2 inches tall, to allow good seed-to-soil contact and reduce competition for new seedlings.

Use a grass seed blend suited to your climate and lawn conditions for the best results.
Rake or dethatch to disturb the soil surface before seeding to create pockets for seeds to establish.
Apply seed according to package rates, either by hand, with a spreader, or by hydroseeding.

Cover the seeds by raking lightly or rolling the area.
Water gently but frequently, keeping the top 1/2 inch of soil moist until seeds germinate.
Allow 4-6 weeks after seeding for new grass to sprout and grow before fertilizing.

When new grass is 3-4 inches tall, apply a balanced starter fertilizer to support continued growth.

Following these steps correctly will give your new grass the best chance to thrive before existing plants are stimulated by fertilizer. Patience is required to wait those critical weeks for new seeds to take hold.

Fertilizing a Newly Seeded Lawn

Fertilizing a newly seeded lawn encourages the young grass plants to establish deep roots and shoots. But it’s vital to wait until the new grass has sprouted and grown for a few weeks before fertilizing to prevent harming the tender new seedlings.

Here are some tips for fertilizing after seeding new grass:

Wait at least 4-6 weeks after seeding to fertilize, or until new grass is 3-4 inches tall.
Organic fertilizers like compost or compost tea can be applied soon after seeding since they release nutrients slowly.

Use a balanced starter fertilizer with a ratio like 10-10-10 or 12-12-12 to provide key nutrients.
Overseeded lawns may need a second application 2-3 weeks after the first to support continued growth.
New lawns from bare ground may only need one application for the first season.

Follow fertilizer rates according to the product, usually 1-2 pounds of actual nitrogen per 1,000 sq ft.
Spread evenly and water in thoroughly after applying.

Proper fertilization is the reward for patience after seeding. Letting young grass establish before fertilizing avoids disrupting the crucial germination and sprouting stages.

Signs It’s Time to Fertilize After Seeding

How do you know exactly when your newly seeded lawn is ready for its first fertilizing? Here are a few key signs to look for:

New grass is at least 3-4 inches tall and has been growing for 4-6 weeks since seeding.
The lawn is completely filled in without thin or bare patches.

Seedlings have developed deeper roots and several leaves.
Grass plants are still light green in color, signaling need for nutrients.
Growth has slowed from the initial sprouting phase.

Existing grass is starting to crowd out or compete with new seedlings.

Seeing these cues means your new lawn is well-established and ready for fertilizer to keep growth strong. Be patient and wait for confirmation to avoid fertilizing too soon.

Choosing a Fertilizer for a New Lawn

With so many fertilizer options on the market, how do you choose one that’s ideal for a newly seeded lawn? Here are some things to look for:

Balanced NPK ratio – Look for a relatively equal ratio between nitrogen, phosphorus, and potassium, such as 10-10-10.
Slow or controlled-release nitrogen – This feeds grass steadily without excessive top growth.
Moderate nitrogen content – Avoid very high or very low nitrogen levels, ideal is 20-25% or so.

Natural organic sources – Compost, animal meals, etc. break down slowly over time.
Starter fertilizer mix – Special blends made just for seeding contain helpful micro-nutrients.
No weed preventers – These chemicals disrupt germination so avoid until later.

Investing in a high-quality starter fertilizer designed for newly seeded areas will give your young grass the best nutritional foundation.

Common Mistakes When Fertilizing After Seeding

While the order of fertilizing after seeding is ideal in most cases, it’s easy to make missteps. Here are some key mistakes to avoid:

Fertilizing too soon – Waiting less than 4 weeks risks burning delicate new seedlings.

Applying too much – More fertilizer won’t speed growth, and can damage tender grass.
Using quick-release nitrogen – This stimulates fast top growth prone to disease and drought stress.
No follow-up application – Most new lawns need a second feeding 2-3 weeks after the first.

Skipping proper watering – Fertilizer needs sufficient watering to dissolve into the soil and be taken up by plants.
Overlap spreading – Apply in a pattern to prevent excess fertilizer pile-up in some areas.
Applying weed preventers – These chemicals disrupt germination so should be avoided until the lawn is mature.

Avoiding these missteps takes patience and proper technique for a successful fertilizing experience after new lawn seeding.

Special Cases for Fertilizing Before Seeding

While fertilizing after seeding is the best practice for most situations, there are a few special cases where you may want to fertilize before or at seeding time:

Establishing a brand new lawn from bare ground – With no existing plants, pre-fertilizing provides nutrients for seeds.

Seeding unusually poor, infertile soil – Starter fertilizer provides an initial nutrient boost.
Using specific slow-release fertilizers – Some break down over many weeks or months.
Hydroseeding or applying seed and fertilizer together – The materials are designed to be combined.

Overseeding very thin or bare lawn areas – Minimal competition allows fertilizing first.
Applying compost or compost tea before seeding – These release nutrients very slowly.

In these unique situations, fertilizing before or during seeding may offer advantages and improve success. But follow product instructions carefully.

Key Takeaways on Fertilizing Before or After Seeding

Here are some key tips to remember:

Seeding first and fertilizing later promotes the best results in most overseeding cases.
Wait 4-6 weeks after seeding for new grass to sprout and establish before fertilizing.

Look for cues like 3-4 inch height and light green color before fertilizing.
Choose a balanced starter fertilizer made for newly seeded lawns.
Special cases like bare ground or poor soil allow fertilizing at or before seeding.

Always follow product rates and instructions carefully to avoid misuse.

Proper timing and techniques for fertilizing around seeding are vital to grow a flourishing new lawn. Patience allows tender grass seedlings to sprout and take hold before being stimulated by fertilizer. Pay close attention to product guidelines for the healthiest seeded lawn possible.

Conclusion

Seeding first before fertilizing is the best practice in most lawn overseeding scenarios. This allows new grass plants to sprout and establish roots to access soil nutrients before existing vegetation is pushed into excessive top growth by fertilizer. But new lawns started from bare ground or very thin existing turf may benefit from fertilizing first or at seeding time. The keys are using quality products suited to seeding, following package rates carefully, and practicing patience. Proper watering and waiting at least 4-6 weeks until new grass is 3-4 inches tall provides the best conditions for fertilizing success after seeding. Avoiding common mistakes like applying too much fertilizer too soon or using quick-release nitrogen prevents disrupting the crucial seed germination stage. With the right timing and techniques guided by signs of establishment, fertilizing after seeding results in a lush, thriving new lawn.