Overseeding Before or After Top Dressing Your Lawn – Which Is Best?

Top dressing and overseeding are two important lawn care practices that help create a lush, thick, and healthy lawn. But what is the best order to perform them – should you overseed first and then top dress, or vice versa? There are good arguments on both sides, so let’s explore the pros and cons of overseeding before and after top dressing.

What is Top Dressing?

Top dressing involves spreading a thin layer of material over the lawn to improve soil structure, fertility, and grass growth Typical top dressing materials include

• Compost
• Quality soil
• Sand
• Peat moss
• Composted manure
• Specially blended mixes

Done properly. top dressing provides the lawn with a range of benefits

• Enriches soil nutrients and organic matter
• Improves moisture retention
• Reduces compaction and aerates soil
• Helps level uneven areas
• Allows for easy seeding and sodding

What is Overseeding?

Overseeding is the process of sowing grass seeds over an existing lawn. It helps fill in thin, patchy areas to create a fuller, denser lawn. Overseeding is performed in early fall or spring when temperatures are milder and the soil has some moisture.

Some key benefits of overseeding include:

• Thickens up thin, bare spots
• Crowds out weed growth
• Introduces improved grass varieties
• Repairs damage from heavy use
• Improves color and texture

Now that we’ve reviewed both practices separately, let’s compare the pros and cons of overseeding before and after top dressing.

Overseeding Before Top Dressing

Spreading grass seed before applying top dressing has some potential advantages:

Pros

• Seeds have direct contact with soil to aid germination
• No barrier between seeds and soil moisture
• Seeds not blocked from sunlight by top dressing layer
• Avoids seeds being swept away when top dressing is applied

Cons

• Seeds may be displaced or uncovered by raking in top dressing
• Uneven seed germination if the layer of top dressing is too thick
• Difficult to ensure good seed-to-soil contact throughout

Overseeding After Top Dressing

Waiting to overseed until after laying down the top dressing layer has some distinct benefits too:

Pros

• Creates a more consistent surface for distributing seed
• Top dressing maintains consistent moisture and temperature
• Seeds adhere well to the prepared seedbed
• Achieves good ground contact for seed germination
• Light top dressing helps anchor seeds in place

Cons

• Too thick of layer can inhibit seed-soil contact
• Seeds may not penetrate thatch layer effectively
• Lack of moisture if top dressing is non-organic

Best Practice Recommendations

So when all factors are considered, what is generally seen as best practice in terms of order for top dressing and overseeding?

Most lawn care experts recommend top dressing first, followed by overseeding as the preferred sequence.

This allows the benefits of a smooth, prepared seedbed, good moisture retention, and proper seed placement to be fully utilized.

However, there are some qualifiers to this recommendation:

• If only a very light, thin layer of top dressing is being applied (less than 1/4 inch), then overseeding first may be fine.

• For very sloped lawns, overseeding first may help anchor seed in place before top dressing.

• When sowing heavy seed varieties like tall fescue, going seed first may work better to avoid burial.

• Cool season grasses tend to do better overseeded before top dressing.

• Warm season grasses seem to benefit more from top dressing first.

So the lawn type, slope, and amount of top dressing should all be factored into the decision. Consulting a professional lawn care service is wise for any large overseeding or top dressing project.

Top Dressing First – Step-by-Step Process

If top dressing before overseeding, follow this detailed process:

1. Mow the lawn short, around 1-2 inches tall. This allows for good top dressing contact.

2. Clear away any debris like leaves, branches or toys from the lawn area.

3. Use a spreader to apply a thin 1/4 inch layer of top dressing uniformly across the lawn. Adjust settings as needed.

4. Gently rake the top dressing into the lawn, taking care not to disrupt the soil. The goal is to create a smooth seedbed.

5. Apply starter fertilizer per product instructions to provide nutrients for seeding.

6. Use a seed spreader to evenly distribute the grass seed over the lawn. Calibrate the spreader settings for the seed variety.

7. Lightly rake over the lawn again to ensure good seed-to-soil contact.

8. Water thoroughly to moisten seedbed. Mist as needed to keep top 1/2 inch moist.

9. Once sprouted, water deeper and less frequently to promote root growth.

10. Allow 4-6 weeks for full germination before mowing new seedlings.

Overseeding Tips for Best Results

To maximize the results from overseeding, incorporate these tips:

• Time overseeding for early fall, when temperatures cool and rainfall increases. Spring overseeding is another option.

• Test soil and address any pH, drainage or nutrient deficiencies beforehand.

• For heavily shaded areas, use shade-tolerant grass mixtures.

• When overseeding warm season grasses, use only varieties matched to existing grass type.

• Water lightly but frequently to keep seeds moist for germination.

• Use pre-germinated seed or seed starter fertilizer to boost sprouting rates.

• Consider dormant overseeding during winter months for warm season grasses.

• Overseed high-traffic areas more heavily for thicker growth and durability.

• Allow newly overseeded areas time to establish before heavy use or mowing.

• Spot overseed thin areas as needed rather than overseeding entire lawn.

Top Dressing Tips for Lawn Improvement

Adhering to some key best practices when top dressing will improve lawn benefits:

• Time top dressing for early fall or early spring when grass is growing more actively.

• Test soil pH and nutrients first; adjust as required to optimize growth.

• Select organic top dressing materials like compost to build soil structure and fertility.

• Spread top dressing evenly and smoothly using a calibrated spreader.

• Apply lighter, multiple layers vs. a single heavy layer for best incorporation.

• Adjust mower height up temporarily after top dressing to avoid grass damage.

• Increase watering by 25% for the first weeks to settle material into soil profile.

• Schedule core aeration and dethatching before top dressing for enhanced results.

• Drag a board or weighted roller across surface to further settle material.

• Top dress consistently on an annual or biannual basis to steadily improve soil.

When to Avoid Top Dressing and Overseeding

While top dressing and overseeding provide substantial benefits, there are certain times they are not recommended:

• Avoid top dressing during hot, dry summer weather when grass is dormant.

• Do not top dress or overseed during a drought or under water restrictions.

• Overseeding cool season grasses in summer will often fail and waste seed.

• Don’t overseed during extremely cold winter months when the ground is frozen.

• Avoid top dressing immediately before or after chemical treatment applications to the lawn.

• Do not top dress or overseed a brand new lawn for the first growing season.

With proper timing and care taken in the application process, both overseeding and top dressing are extremely beneficial for improving lawn thickness, texture, color and overall beauty. Just be sure to consider all factors including grass type, climate, layer thickness and timing when deciding the ideal order to perform them in.