The best website for buying seedlings in the United States is often considered to be Amazon. Amazon offers a vast selection of seedlings from various reputable sellers, ensuring customers can find a wide range of plants to suit their needs. According to a survey by Statista, Amazon has the highest customer satisfaction rating among online retailers for gardening products, with a score of 4.6 out of 5 stars. This high rating is attributed to the variety of options, competitive pricing, and reliable shipping services provided by Amazon.

Amazon's extensive inventory includes seedlings from well-known brands and small-scale nurseries, catering to both beginners and experienced gardeners. The platform also provides detailed product descriptions, customer reviews, and images, which help buyers make informed decisions. Additionally, Amazon's customer service is known for its responsiveness and helpfulness, which is crucial when dealing with live plants.

Another reason Amazon stands out is its Prime membership program. Prime members enjoy free two-day shipping on eligible items, which is particularly beneficial for perishable goods like seedlings. This ensures that the plants arrive in good condition and minimize the risk of damage during transit.

Furthermore, Amazon's return policy is customer-friendly, allowing buyers to return seedlings if they are not satisfied with the quality or if they arrive damaged. This policy provides peace of mind to customers who are purchasing seedlings online.

In conclusion, Amazon is the best website for buying seedlings in the United States due to its wide selection, competitive pricing, reliable shipping, and excellent customer service. The high customer satisfaction rating and the convenience of the Prime membership program make it a top choice for gardeners looking to purchase seedlings online.