Many travelers stop in Odawara to change trains on their way to Hakone. However, if you like the outdoors then spend some time exploring Odawara Flower Garden and Odawara Castle.
The flower garden was established in 1995 as an urban greening park. This 10.4-acre garden is popular for its plum festival every February. There are 480 plum trees with 200 varieties. Then in late May/June you can see beautiful displays of iris, water lilies, and hydrangea. In July there are the sunflowers. There is also a very large tropical greenhouse featuring plants from Asia, and South America. During our most recent visit we witnessed an Alcantarea Imperialis in bloom, which for this particular Brazilian plant only happens every ten years. There is a small fee to enter the greenhouse, the rest of the garden is free. Just outside the greenhouse is a nice rose garden with over 100 types of roses. There are many excellent walking paths for your exercise and a good view of the top of Mt Fuji.
You can take a bus directly from Odawara Station or get on the Daiyuzan Line for Iidaoka Station, which is a 20-minute walk to the park.
Back at Odawara Station take a short walk to Odawara Castle. Originally built in 1447 this castle was torn down, destroyed by earthquakes, rebuilt, expanded, downsized, and recently restored. It is not the most impressive in Japan, but the castle park makes it worth seeing. It too has very impressive flower seasons with plum trees, cherry blossoms, iris, lotus, and a most notable hydrangea display. You can even dress up like a Samurai Warrior for some memorable picture-taking. There are several museums on the grounds, samurai history lessons, as well as many restored castle gates.
On your walk back, be sure to explore the new section of Odawara Station that looks like an historic Onsen. There are some great shops and restaurants including Yokohama based Karubi Ramen. Their spicy ramen is excellent and you can tell them how hot you want it.
Odawara has many other attractions and is a great place to visit for a day trip from Tokyo.