Airflow is the entire specification
Curing is controlled drying. You are driving moisture out of the outer layers of a crop so the skin sets and seals, which is what turns a squash that rots in three weeks into one that keeps until spring. Everything that goes wrong with curing goes wrong because air could not get to a surface.
That gives you one buying criterion that outranks all others: can air reach every face of the crop, including the underside? A solid shelf fails this immediately. Squash cured on a solid board develops a soft contact patch that goes first and takes the rest with it. Onions in a heap cure on the outside and rot in the middle.
Mesh, wire, slatted timber and hanging nets all pass. Solid plastic, plywood and cardboard do not. That single distinction is most of the decision, and it is why cheap mesh shelving frequently outperforms expensive furniture for this job.
A greenhouse is a great curing room and a poor store.
Through September and October a greenhouse gives you warmth, airflow and light — close to ideal for curing. By December it swings twenty degrees between noon and midnight and drops below freezing, which is close to the worst possible storage environment. Cure under glass, then move things somewhere dark, cool and stable. The technique side of this is covered in curing and storing squash, onions and garlic.
What each crop needs from the rack
Winter squash and pumpkins
Heavy, bulky, and needing air underneath more than anything else. A wire shelf or a slatted bench with the fruit spaced so nothing touches. Weight is the constraint here — a shelf holding a dozen winter squash is carrying serious load, and lightweight wire units sag. Check the per-shelf rating rather than assuming.
Onions and shallots
Cure with the tops still on, either laid in a single layer on mesh or tied and hung. Hanging is the traditional method for good reason: it gives total air access and uses vertical space, which is the space a greenhouse has going spare in autumn. Nets and braided strings both work.
Garlic
The same as onions but slower and more sensitive. Bundle in small bunches and hang, or lay single-layer on mesh. Do not stack, and do not wash the bulbs — brush soil off dry.
Potatoes
Different problem. Potatoes cure briefly and then need darkness immediately, because light greens them and makes them inedible. A greenhouse works for the two-week curing period only if the crop is covered, and then they must go to a dark store. Solid-sided crates with a cover are the right container.
The four rack types
Wire mesh shelving units
The general-purpose answer. Freestanding, several tiers, moves in and out of the greenhouse in autumn, and doubles as staging the rest of the year. Look at the shelf load rating and the shelf spacing — squash need real headroom, salad trays do not.
Hanging nets and drying bags
The best use of a greenhouse in autumn, because they use the roof volume that is otherwise empty. Cheap, collapsible, store flat. Hang from the ridge or a purlin, keep them clear of the glass so air circulates on all sides, and do not overfill — a bulging net is a heap by another name.
Slatted timber benches
If you already have staging with slatted tops you have a curing bench. If your staging is solid, a sheet of mesh or a few battens laid across it converts it for the season.
Stackable ventilated crates
The transition item: cure on the rack, then move into crates for the trip to storage. Ventilated sides, stackable without crushing the layer below, and stackable empty for the rest of the year. This is where most of your crop ends up living, so buy them in a size you can actually lift when full.
Setting the space up
Put curing racks in the part of the greenhouse with the most air movement and the least direct midday sun — usually not the south-facing bench. Direct sun on cured onions scalds them.
Keep a fan running or a vent open. Still air with a load of wet crop in it raises humidity fast, and high humidity is the enemy of curing and the friend of mold. This is the same discipline as everywhere else in the fall greenhouse, and it is covered in autumn condensation and gray mold.
Leave gaps. Every piece of produce should be able to see daylight past its neighbours. It feels wasteful of space and it is the difference between a crop that keeps and one that does not.
What to buy
Wire mesh shelving unit
$$ · The general-purpose rack · check the per-shelf load rating
Four or five tiers of open wire on a freestanding frame handles squash, trays of onions and drying herbs, then works as staging for the rest of the year. Load rating matters more than tier count — a shelf of winter squash is heavy, and cheap units sag in the middle where the fruit sits.
Hanging drying nets
$ · Onions, garlic and herbs · uses the empty roof volume
Multi-tier mesh nets hung from the ridge give total air access and cost almost nothing. They collapse flat for storage and they use the vertical space a greenhouse has spare in autumn. Do not overfill — a bulging net is just a heap in a bag.
Ventilated stackable crates
$ to $$ · Cure, then store · buy a size you can lift when full
Open-sided crates that stack without crushing the layer beneath are what your crop lives in after curing. Stackable-empty designs matter more than they sound, because these things spend nine months a year not in use.
Ventilated storage crates on AmazonVentilated storage crates on eBay
Slatted bench top or mesh sheet
$ · Convert existing staging · airflow underneath
If your staging is solid, a mesh sheet or a few battens laid on top converts it into a curing surface for the season. Solid shelving creates a contact patch on every squash that will be the first place it rots.
Small circulation fan
$ · Airflow · the cheap insurance on a damp autumn
A load of freshly harvested crop puts a lot of moisture into a small volume of air. A small fan moving air across the racks does more for curing success than any amount of shelf quality, particularly in a cool, still autumn week.
What the rack does the rest of the year
Curing gear that only works for six weeks a year is hard to justify in a small greenhouse. Buy for dual use. Wire shelving becomes seed-tray staging in spring. Nets store flat behind the door. Crates hold pots and tools. The circulation fan is doing useful work every damp month of the year, not just in October.
Clean everything before it goes away. Soil and crop debris left on racks over winter is exactly the disease carryover that the end-of-season sanitation window exists to eliminate.
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Common questions
Can I cure squash in the greenhouse?
Yes, and through September and October it is close to an ideal space — warm, bright and airy. Space the fruit so nothing touches, keep them off solid surfaces so air reaches the underside, and move them to a cool dark store once the skins have hardened.
Why do my onions rot in storage?
Almost always incomplete curing, and almost always because they were cured in a heap or on a solid surface. Onions need air on every side, in a single layer on mesh or hung in nets, until the necks are fully dry and papery.
Is a greenhouse a good place to store vegetables over winter?
No. It is excellent for curing in early autumn and poor for storage after that, because the temperature swings widely between day and night and drops below freezing. Cure under glass, then move produce somewhere dark, cool and stable.
Do I need a fan for curing?
Not always, but it is cheap insurance. A load of freshly harvested crop releases a lot of moisture into a small volume, and in a still, cool, damp week that humidity stalls curing and invites mold. A small circulation fan does more for results than better shelving.
Can I cure potatoes in the greenhouse?
Only if they are covered. Potatoes need a short curing period and then darkness, because light turns them green and inedible. Use solid-sided crates with a cover, and move them to a dark store as soon as the skins have set.