Storing baseball cards in a garage can be okay as long as certain conditions and precautions are met. Garages typically are not climate controlled spaces like indoor areas of a home, so they can expose items stored there to temperature fluctuations and humidity changes that can potentially damage collections over time if not properly protected. Some key factors to consider regarding garage storage of baseball cards include:

Temperature variations – Garages often experience wider temperature swings between day and night, and between summer and winter. Rapid changes or extended periods of high heat or cold can cause baseball cards to warp, wrinkle, or become brittle. Cards are best stored in a more consistent indoor environment between 50-70°F if possible. Proper insulation, storage boxes, and heating/cooling can help regulate temperature fluctuations in a garage.

Humidity levels – Changes in humidity, especially high humidity, promote mold and mildew growth which can damage cardboard and paper over time. Storing cards in airtight containers with silica gel packs or a dehumidifier run in the garage can control humidity levels. Very low humidity can also cause brittleness, so some moisture is needed. The ideal humidity range is between 40-50%.

Direct sunlight – Sunlight, especially UV rays, causes physical damage and fading to cardboard, inks, and photographs on baseball cards left exposed over years. Ensure cards are not placed in direct path of any windows and are stored in protective boxes instead of loose in stacks. Even indirect light exposure should be limited as much as possible.

Dust and dirt particles – Fine dust and dirt that settles in an unsealed garage can slowly ruin cardboard and images on cards when repeatedly introduced over many years. Airtight storage containers and regular vacuuming/cleaning of the garage space helps prevent accumulation and protects collections.

Pests and rodents – Mice, insects, and other pests may be attracted to cardboard and paper collections in a garage space unless proper precautions are taken. Airtight storage containers and pest control/repellents around the storage area are essential to safeguard against damage from infestations.

Structural issues – Factors like a leaky roof, standing water, warping wood shelves/cabinets prone to collapse, and other structural problems common to garages increase risks to long-term storage of valuable collectibles. Ensuring a sound, dry structure is a must.

Theft potential – While many consider a locked garage reasonably secure day-to-day, high value collections are more at risk than items locked inside the home. Proper security measures like an alarm system provide needed peace of mind for items stored long-term in an outbuilding. Documenting serial numbers of valuable collections aids recovery if theft occurs.

Organizing and accessibility – It can be challenging to efficiently organize large baseball card collections in cramped garage spaces, find specific cards when needed, and maintain the organization long-term compared to dedicated storage space inside. Proper shelving, cabinets, and tracking systems are important.

With the right setup and controls for temperature, humidity, light, pests, security, and organization – and if the structure, insulation and ventilation of the space allow adequate environmental regulation – a garage can certainly host baseball card collections safely when careful precautions are taken. But the ideal storage location remains an indoor area of the home like a laundry/utility room, spare bedroom, or basement if space allows for optimal long-term preservation of the cards. Regular inspection and maintenance is also needed since risks increase over many years in an outdoor-connected area like a garage.

While garage storage isn’t recommended long-term without stringent controls due to greater risk factors, it can work with diligent safeguards and monitoring in place. Proper containers, consistent climate regulation, integrated pest management, structural soundness, thorough cleaning, documentation, and secured access are all important to preserve valuable baseball card collections for years to come when using any non-climate controlled storage space. With the right setup and maintenance routines, a climate-regulated garage can suffice, but an indoor-oriented area remains preferable when possible for collections protection and longevity. Regular collection assessment also wise to catch any developing issues early.