How much grass seed to overseed bare patches: complete guide

Why grass seed overseeding is better than doing nothing

Bare patches in your lawn spread into weed invasions. One bare spot attracts dandelions, plantain, and other weeds. Within a season your whole lawn is taken over. Grass seed overseeding is the only way to prevent this.

Grass seed is cheap, simple, and works. The art is knowing how much you need and when to sow. Sow too little and you do not fill it. Sow too much and you waste money (and seed takes effort to incorporate properly).

TL;DR

For bare patch overseeding: 25-50g per m2 depending on:

• Small (pinhole): 25g/m2
• Medium (hand-sized patch): 35g/m2
• Large (meter-sized gap): 50g/m2
• Very large (whole zone bare): 40g/m2 plus extra feeding

Best time: March-May (spring) or September-October (autumn). Avoid summer (dry) and winter (frozen).

Small bare patches (10-30 cm): 25g per m2

For small pinhole holes (e.g. dead grass after ant nests) use 25g per m2. This feels minimal, but for small patches it is perfect. You sow lightly, seeds germinate, and you have not wasted excess seed.

Practical: a small hole 20x20 cm (0.04 m2) needs roughly 1g seed. This sounds very little, but it is enough. Seed is tiny and sowing density is high.

Procedure:

1. Mow grass short (2-3 cm)
2. Rake out loose dead grass (thatch)
3. Lightly scatter seed
4. Gently press with back of rake
5. Water well, keep moist 2-3 weeks

Medium bare patches (30-100 cm): 35g per m2

For hand-sized to somewhat larger patches use 35g per m2. This is your "standard" overseeding rate. It provides enough seed to germinate well, without overdosing.

Practical: a patch 60x60 cm (0.36 m2) needs roughly 12-13g seed. This is a small handful.

Procedure:

1. Mow short (2 cm)
2. Rake out dead grass
3. Lightly scratch a seedbed: gently work the ground
4. Scatter seed evenly
5. Cover very lightly with seedbed (2-3 mm compost helps) or press with rake
6. Water daily until growth visible

Large bare patches (1+ meter): 40-50g per m2

For large holes (e.g. after dog damage or heavy traffic) use 40-50g per m2. This is your "intensive repair" rate. More seed helps larger zones fill faster.

Practical: a patch 1x1 meter (1 m2) needs 40-50g seed. This is a substantial handful and visible work.

Procedure:

1. Mow short (1-2 cm)
2. Rake out dead grass very thoroughly - you want bare soil visible
3. Loosen soil with a fork (5-10 cm deep)
4. Add compost (2-3 cm) and mix well in
5. Scatter seed evenly
6. Cover very lightly with compost (1-2 cm)
7. Water daily until full growth (4-6 weeks)

This gives seed all advantages: loose soil, feeding, and moisture.

Very large or whole-lawn overseeding: 35-40g per m2

Sometimes you need to overseed your whole lawn (e.g. worn lawn, thin lawn, lots of weed space). Use 35-40g per m2 for the whole lawn. This is quite intensive and requires preparation.

Procedure:

1. Mow very short (1-2 cm, possibly twice)
2. Scarify (rake hard) VERY thoroughly to remove dead grass
3. Add seedbed: 2-3 cm compost or seedbed mix
4. Scatter seed evenly (use a spreader for large areas)
5. Cover lightly with seedbed and sand-compost mix
6. Water daily until strong growth (6-8 weeks)
7. No traffic until lawn is 5 cm

This is larger work but absolutely necessary for weak lawn.

Grass seed type determines result

Not all seed is equal:

Premium blend (5-7 species, Red Fescue/Perennial Ryegrass/Finest Bents): Better germination, faster completion, finer texture. Pay more.

Budget blend (2-3 species, lots of Perennial Ryegrass): Fast growth but coarser, less attractive. Cheaper.

Standard blend (3-4 species, good balance): This is what most gardeners use. Fine results.

For very bare, problem zones use premium. For maintenance: standard is fine.

Feeding: Just as important as seed

Grass seed germinates well but grows weak without feeding. The substrate where you sow is often lean (especially if it has been lawn for years).

Solution: Add feeding BEFORE sowing:

1. For small patches: Some compost mixed in suffices
2. For medium: 2 cm compost added and mixed
3. For large: Seed fertiliser (artificial fertiliser) applied AFTER you scatter seed
   • Rate: 20-30g per m2
   • Timing: Right after sowing or at day 10

Feeding gives seed energy to grow into normal grass size.

Timing: When to overseed?

March-May (spring): BEST TIME. Soil warm, water available, seed grows fast. Choose April as optimal.

September-October (autumn): GOOD. Soil still warm, rain coming. Very suitable.

June-August (summer): AVOID. Dry, seed dries out, young grass withers. Only overseed if you can water heavily (sprinkler daily).

November-February (winter): AVOID. Frozen soil, seed lies dormant, rain washes it. Do not do this.

So: Sow seed in April OR October. These two months are optimal.

Water: Critical for success

Seed needs moisture to germinate (3-7 days), and young grass needs constant moisture (3-4 weeks).

For small overseeding: Hand-water daily (small watering can) until you see growth (2-3 weeks).

For medium-large: Sprinkler daily or every other day, 20-30 min total, enough so soil is moist 5 cm deep.

For whole-lawn: Sprinkler daily, very consistent. This is why many people fail: they stop after 2 weeks. Tell yourself: 6 weeks of watering.

Too little water = no growth. Too much water = waterlogging and fungal disease. Moist, not dry or wet.

Frequently asked questions

How long until I have grass?

• Seed germination: 5-10 days in good weather
• Visible growth: 10-14 days
• 5 cm tall: 3-4 weeks
• Ready to mow: 5-6 weeks
• Mature lawn: 8-12 weeks

This is why patience matters. Many gardeners think: "It is not growing" after 2 weeks. Wait until week 4-5.

Can I use seed and fertiliser simultaneously?

Yes, with caution. Fertiliser can "burn" seed if too strong. Better: sow seed, water well, and add feeding at DAY 7-10 when seed germinates. This gives seed feeding without too much salt.

What if my seed does not germinate?

Likely causes:

1. Too dry (most likely)
2. Seed too old/bad (rare)
3. Soil too hard (you did not press, seed has no soil contact)
4. Soil too wet/poor drainage
5. Foot traffic on seedbed

Check first: is soil moist to 2-3 cm deep? Yes = wait longer. No = water more. This usually fixes everything.

Can I sow seed on existing grass without preparation?

No, this almost never works. Seed needs soil contact. Existing grass blocks this. Always prepare:

1. Mow very short
2. Rake out dead grass
3. Loosen soil slightly
4. SOW
5. Cover lightly with seedbed

Without this = wasted seed.

Step-by-step

Step 1: Measure your bare patch

Small (< 0.3 m2): 25g seed Medium (0.3-1 m2): 35-40g seed Large (> 1 m2): 40-50g seed

Step 2: Prepare soil

Mow short, rake out dead grass, loosen soil.

Step 3: Add compost (especially for larger)

2-3 cm for large patches, bit for small.

Step 4: Scatter seed evenly

Distribute uniformly over patch.

Step 5: Cover lightly and press

Seedbed or light compost plus gentle firming.

Step 6: Water daily

At least 6 weeks, moist but not wet.

Step 7: Mow at 5 cm height

After 6 weeks you can mow. Ensure mower is sharp (young grass is tender).

Frequently asked questions

How much seed do I keep for next year?

Seed loses vigour after 1 year storage. Store in cool, dry place. After 1-2 years: germination drops fast. Better: buy new seed each year. Price difference is small, germination benefit large.

Can I mix seed with sand for better spreading?

Yes, this is a good trick, especially for large area. Mix: 1 part seed, 3-4 parts sand. This helps distribute evenly. Make sure you have enough seed (calculate without sand, add sand).

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Frequently asked questions

How much does grass seed cost?

Premium blend (1 kg): EUR 15-25, good for 25-40 m2. Budget blend: EUR 8-12 per kg.

For small overseeding (0.5 m2): EUR 1-2 seed needed. Very cheap.

Can I sow grass seed also in autumn?

Yes! October is nearly as good as April. Soil still warm, rain coming. If your lawn is weak now, autumn-sowing helps it through winter. Spring-sowing gives summer advantage.

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