Seed trays are the sort of kit most of us buy once, barely think about, and then quietly curse every spring when last year’s flimsy ones crack in half and tip a tray of tomato seedlings across the potting bench. Get the right ones, though, and they’ll see you through a decade of sowing without complaint. The difference between a tray that lasts fifteen years and one that lasts a single season usually comes down to the plastic it’s made from and how it’s put together.
In this guide we’ve gathered the seed trays we rate most highly for UK gardens, from cheap-and-cheerful standards for mass sowing to self-watering propagators and specialist rootrainers for fussy, deep-rooted crops. There’s something here whether you’re starting a windowsill full of chillies or sowing hundreds of module-grown veg for the allotment. We’ve stuck to trays that are easy to find from UK suppliers such as Amazon UK, B&Q and specialist growers.
What to look for in a seed tray
Plastic type and thickness
This is the single biggest factor in how long a tray lasts. Cheap trays are vacuum-formed from thin plastic and go brittle after a season or two, especially if they’ve spent the summer in a hot greenhouse where UV light attacks the material. Heavy-duty trays are injection-moulded from thick (often 2mm) polypropylene, frequently UV-stabilised and made from recycled plastic. They cost more up front but can last well over a decade, which makes them cheaper per season and far kinder to the bin.
Solid base or drainage holes?
Standard seed trays come in two flavours. Trays with drainage holes are for sowing directly into compost, letting excess water escape so seedlings don’t sit wet and damp off. Solid, watertight trays (sometimes called gravel trays) are designed to hold pots, modules or inserts, and to let you water from below. Many gardeners keep a mix of both, standing a holed tray inside a solid one so they can water without making a mess.
Full size, half size or modular
A full-size standard tray is roughly 37 x 22cm, the industry standard that most propagator lids, capillary matting and inserts are built to fit. Half-size trays suit a windowsill or a small propagator. Modular inserts divide a tray into cells, so each seedling grows in its own plug of compost and can be pricked out with minimal root disturbance. If you sow a lot of veg, module trays save time and give sturdier young plants.
Watering and warmth
Even watering is where a lot of seedlings are won or lost. Self-watering trays use a reservoir and capillary matting to keep compost evenly moist, which takes the guesswork out of it and is handy if you can’t check them every day. For heat-loving seeds like tomatoes, chillies and aubergines, pair any tray with a heated propagator base or a heat mat rather than relying on a windowsill alone.
Seed trays at a glance
| Seed tray | Best for | Type | Guide price |
| Standard vacuum-formed trays (multipack) | Tightest budget / mass sowing | Thin plastic | Around £5–8 for 5 |
| Garland Heavy Duty Standard Seed Tray | Best all-round value | 2mm recycled | Around £3–5 each |
| Garland Professional Seed Trays (pack of 5) | Regular sowers | Injection-moulded | Around £15–20 |
| Garland Self-Watering Seed Tray Propagator | Hands-off watering | 24-cell + reservoir | Around £15–22 |
| Reusable silicone seed trays | Easiest to pop out seedlings | Flexible silicone | Around £10–15 |
| Garland Modular Cell Inserts | Pricking out / module sowing | 24–40 cell insert | Around £2–4 each |
| Haxnicks Deep Rootrainers (32 cell) | Deep-rooted crops | Reusable kit + lid | Around £22–30 |
The best seed trays for 2026
1. Standard vacuum-formed seed trays (multipack) — best for the tightest budget
You’ll find these in every garden centre and DIY shop: thin, black, full-size trays sold in packs of five or ten for a few pounds. For a single season of heavy sowing, or if you want a stack of cheap trays to hold pots, they do the job and cost almost nothing. Just go in with your eyes open, they’re not built to last.
The thin plastic flexes alarmingly when full and tends to crack around the corners once it’s been out in the sun, so most people get one or two seasons before they start splitting. If you sow a lot and don’t mind replacing them, they’re still cheaper over five years than you might think, but the throwaway cycle isn’t ideal.
Pros: extremely cheap; widely available; fine for one season or holding pots. Cons: brittle after a season; flex when full; not an eco-friendly choice long term.
2. Garland Heavy Duty Standard Seed Tray — best all-round value
If we had to point most gardeners at one tray, it would be this. Garland make their heavy-duty standards in the UK from tough 2mm injection-moulded recycled plastic, in the classic full-size 37 x 22cm footprint that fits standard propagator lids and inserts. They come with or without drainage holes, so you can buy exactly what you need for sowing or for standing pots.
The difference in feel compared with a bargain tray is obvious the moment you pick one up, there’s almost no flex even when it’s packed with wet compost, and they shrug off years of use. At only a pound or two more than the flimsy versions, they’re the easy value pick and the ones we’d stock up on.
Pros: genuinely durable 2mm plastic; UK-made from recycled material; standard size fits everything; choice of holes or solid. Cons: dearer than throwaway trays; only worth it if you’ll reuse them.
3. Garland Professional Seed Trays (pack of 5) — best for regular sowers
For anyone sowing every week through spring, buying the heavy-duty trays as a five-pack works out sensibly and gives you a matching, stackable set. These are the same robust injection-moulded build, sized to the professional standard so they nest neatly and store flat over winter.
There’s nothing flashy here, they’re simply well-made trays bought in a cost-effective bundle. If you already know you get through a lot of trays, this is the tidy way to do it, and a set will comfortably outlast a decade of springs.
Pros: sturdy and stackable; good value in a multipack; long lifespan; consistent sizing. Cons: more trays than a casual gardener needs; plain, no-frills design.
4. Garland Self-Watering Seed Tray Propagator — best for hands-off watering
If the thing that trips you up is watering, either forgetting, or drowning seedlings with a heavy hand, a self-watering tray takes the decision away. Garland’s self-watering propagator uses a reservoir and capillary matting to draw moisture up into the compost, keeping it evenly damp without you touching the seedlings. The version we’d point to holds 24 cells under a clear lid.
It isn’t heated, so for tropical seeds you’ll still want a warm spot or a heat mat underneath, and you do need to keep an eye on the reservoir. But for reliable, fuss-free germination, especially if you’re out at work all day, it removes one of the most common causes of failure.
Pros: even, reliable moisture; forgiving for beginners; clear lid included. Cons: not heated; reservoir needs topping up; more expensive than a plain tray.
5. Reusable silicone seed trays — easiest to pop out seedlings
Silicone module trays are a newer arrival and they solve one specific annoyance beautifully: getting seedlings out without wrecking the roots. Because the cells flex, you push from underneath and the whole plug lifts out cleanly, compost and all. They have drainage holes, fold flat for storage and most are dishwasher safe, so cleaning is painless.
The trade-off is that a floppy tray needs supporting on a firm base or a solid tray when you move it, or it’ll bend and spill. They also cost more than the same number of plastic cells. But for pricking out with minimal root shock, they’re a lovely thing to use and they should last for many years.
Pros: seedlings pop out cleanly; dishwasher safe; folds flat; very long-lasting. Cons: needs a rigid base to carry; pricier per cell than plastic.
6. Garland Modular Cell Inserts — best for pricking out and module sowing
Inserts turn a standard tray into a grid of individual cells, and they’re the secret to raising strong, evenly-spaced young plants. Garland’s inserts drop straight into their standard trays and come in cell counts from around 24 up to 40, letting you match the cell size to the crop, bigger cells for beans and squash, smaller ones for lettuce and brassicas.
Sowing one or two seeds per cell means each seedling grows its own root plug and transplants with barely a check, which beats untangling a crowded tray. They’re cheap, but do buy the heavy-duty inserts rather than the wafer-thin ones, the flimsy sort tear when you push seedlings out.
Pros: cheap; less root disturbance; choice of cell sizes; fits standard trays. Cons: thin versions tear easily; you’ll want a tray to hold them.
7. Haxnicks Deep Rootrainers (32 cell) — premium pick for deep-rooted crops
Some plants hate having their roots disturbed and want depth to grow into, sweet peas, broad and runner beans, and long-rooted perennials among them. Rootrainers are the specialist answer. The deep cells have vertical ridges that train roots straight down instead of spiralling, and the books hinge open like a paperback so you can inspect the roots and slide the plug out without any tugging.
The Haxnicks kit comes as a holding tray, eight hinged books giving 32 deep cells, and a clear propagating lid, all reusable year after year. It’s more of an investment than a bag of plastic cells and it’s overkill for shallow-rooted salads, but for beans and sweet peas the results speak for themselves.
Pros: deep cells for strong taproots; books open for easy, damage-free transplanting; complete reusable kit with lid. Cons: pricey; unnecessary for shallow-rooted crops; more storage bulk.
Which seed trays should you buy?
For most gardeners the honest answer is a stack of Garland heavy-duty standards, some with holes for sowing and a few solid ones to water from below. They cost barely more than the throwaway trays and you’ll still be using them in fifteen years. Add a set of modular inserts if you grow a lot of veg, since module-grown plants transplant so much more happily.
If watering is your weak spot, or you’re often away, the self-watering propagator is worth the extra. Beginners in particular tend to have far more success once the moisture looks after itself. Silicone trays are the treat-yourself option for anyone who loves pricking out and wants the cleanest possible job.
And if you’re sowing sweet peas or beans, buy the Haxnicks Deep Rootrainers alongside your standard trays, they’re the one job where the specialist kit genuinely earns its place. Only reach for the cheapest vacuum-formed trays if you truly need something disposable for a single big sowing.
Looking after your seed trays
Good trays reward a little care with years of extra life. At the end of each season, knock out the old compost and give trays a wash in warm water with a drop of washing-up liquid, or a mild garden disinfectant if you’ve had any disease, to kill off fungal spores that cause damping-off. Let them dry fully before stacking.
Store them out of direct sunlight over winter, a shed or garage is ideal, because UV light is what makes plastic go brittle. Stack same-size trays together so they don’t warp, and keep lids somewhere they won’t get crushed. Treated this way, a decent tray will comfortably outlast the label that came on it.
Frequently asked questions
What size is a standard seed tray?
The UK standard full-size seed tray is roughly 37 x 22cm. Almost all propagator lids, capillary matting and cell inserts are made to fit this footprint, so sticking to standard-size trays makes it easy to mix and match components. Half-size trays (around 22 x 17cm) suit windowsills and small propagators.
Do seed trays need drainage holes?
For sowing seeds directly into compost, yes, drainage holes let excess water escape so seedlings don’t sit soggy and rot. Solid trays without holes are useful too, but for holding pots and modules or for watering from below. Many gardeners stand a holed tray inside a solid one to get the best of both.
Can you reuse plastic seed trays?
Absolutely, and you should. Good-quality injection-moulded trays are designed to last many years. The key is to clean them between seasons to remove disease spores, and to store them out of sunlight so the plastic doesn’t degrade. Only the very thinnest vacuum-formed trays tend to crack before they can be reused much.
What is the difference between seed trays and modules?
A plain seed tray is one open space where you scatter seed and prick out the seedlings later. Module or cell trays divide that space into individual cells, so each seedling grows its own compact root plug and transplants with almost no disturbance. Modules mean less root damage and sturdier young plants, at the cost of a little more fiddly sowing.
Are biodegradable seed trays worth it?
Biodegradable pots and trays made from coir, paper or fibre let you plant the whole thing straight into the ground, which suits root-shy crops. They’re handy but single-use, they break down over a season, so they work out dearer over time than a durable plastic tray you reuse for years. Many gardeners use both: fibre pots for the fussiest plants, reusable trays for everything else.
