If you have a big lawn to sow, little boxes of grass seed soon become an expensive way of doing it. A 20kg bag starts to look much more sensible — but I would check what is inside it, how much you can realistically sow and the delivered price before choosing the biggest pack.
For a large, hard-working lawn, I would start with Hurrells HM4. For a family garden where you also want a finer-looking finish, HM3 is worth the extra comparison. Both come in larger quantities. The useful saving comes from buying enough of the right mixture, then giving it the preparation and aftercare it needs.
I personally use Hurrells seed for most lawn work — it’s consistent, reliable, and suited to UK conditions.
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Which grass seed would I buy for a large lawn?
A large lawn might be a play space, a smart garden around the house or a rougher area beyond it. I would choose the mixture for the way you use the ground before worrying about whether the bag says “professional” or “bulk”.
A lawn that needs to cope with plenty of use
HM4 General Amenity is my starting point for a practical, well-used lawn. It combines 50% dwarf perennial ryegrass with 50% strong creeping red fescue. Hurrells positions it for rapid establishment and recovery from wear, including domestic lawns and larger amenity areas.
It is a general-purpose mixture for ground you want to use and mow, rather than an ornamental lawn that needs delicate treatment. I would still compare its current delivered price against the other suitable mixes; “general amenity” does not automatically mean the cheapest order.
A family lawn where appearance matters too
HM3 Hard Wearing Lawn has a broader blend, with 30% dwarf perennial ryegrass alongside fescues, meadow grass and browntop bent. I would shortlist it where a good-looking garden lawn and everyday wear both matter. It is not a promise of a maintenance-free lawn, and I would not buy it simply because the blend contains more species.
If those two sound close to what you need, my HM3 and HM4 comparison goes further into the choice. If much of the lawn is under trees, start with the conditions in my grass seed buying guide before committing to a large quantity.
Is a 20kg bag the right size for your job?
Hurrells lists a 20kg bag of HM4 or HM3 for approximately 560m² of new lawn or 800m² of overseeding. That is a useful buying reference, not a universal coverage figure for every grass seed.
For a 1,000m² lawn being overseeded at 25g/m², you need 25kg. One 20kg bag falls short, while two leave 15kg unused. A 20kg plus 5kg combination may suit the job better, even if the larger bags have a lower price per kilogram. Compare the totals before paying.
If the same 1,000m² is completely bare, it needs the new-lawn rate instead. Do not budget from the larger overseeding coverage printed on a listing. My grass seed quantity guide explains measuring irregular lawns and treating bare patches separately.
For a much larger area, such as 4,000m² of overseeding at 25g/m², the requirement is 100kg. That is where I would compare a bulk quantity against individual bags and check the delivery arrangements. You want a clear specification for the mixture and the amount supplied, not just a photograph of a sack.
Compare the cost of the job, not just the cost per kilogram
When ordering seed for customers’ lawns, I calculate the total cost of completing the job. Include delivery, any usable discount and the pack combination you actually need. A headline price may belong to the smallest size in the dropdown.
Here is a hypothetical example. You need 25kg. A 20kg bag costs £80 and a 5kg bag costs £30, so the exact quantity costs £110. Two 20kg bags cost £160. The bigger order has the cheaper price per kilogram, but it takes another £50 out of your pocket and leaves 15kg to store. These are example prices, not current offers.
That surplus is useful if you have another suitable area ready soon. It is much less attractive if it sits in a damp shed while you wait for a job that may never happen. I would not sow it more heavily just to empty the bag: crowded seedlings still need light, water and space.
- Compare like with like: the same type of mixture, intended use and sowing rate.
- Check the selected weight: the price beside a product title may change when you select 20kg.
- Count delivery once for the whole order: a small extra pack can change the best combination.
- Value leftovers honestly: seed with no planned use is money tied up in storage.
Can you look after that much new grass at once?
It is easy to buy enough seed for the whole garden; keeping a large seedbed evenly moist can be much harder. Check how far the hose reaches, where you can move a sprinkler and whether you can keep people and dogs off the newly sown sections.
If that is awkward, split the renovation into manageable areas. Keep a usable route through the garden and choose a sequence you can water properly. Buy for the work you can complete in the suitable weather window, rather than stripping the whole lawn and hoping the forecast helps.
Both HM3 and HM4 specify soil temperatures of at least 10°C. In autumn, a mild afternoon does not tell you that the soil will stay warm enough. Check conditions and the establishment window in my guide to when to sow grass seed. A bulk discount is not a reason to sow into cold, saturated ground.
Make a large order easier to handle
I would check where the delivery can be left before it arrives. A 20kg sack is awkward enough; several sacks need somewhere dry and accessible. Do not plan to leave them on an exposed drive while you clear space in the shed.
Keep seed dry, cool and protected from rodents, with the mixture and batch details attached. For phased work, keep unopened bags sealed until needed. If you already have seed left from a previous job, assess that before ordering more rather than assuming either that it is useless or that it will germinate like fresh seed.
On the lawn, weigh out a section’s allocation into a manageable container. You do not need to lift the whole sack into the hopper. Check the spreader’s capacity, and calibrate with the actual mixture: grass seed behaves differently from fertiliser, even in the same machine.
My spreader calibration guide will help you check the output before you commit the whole order to the grass. On a large area, a small rate error becomes a lot of seed.
