Poonhill trekking is possible even without guide. But taking Poonhill trek without guide will mean that you will miss extra information that the guide would have made known to you. Besides, taking no guide means you need to arrange everything for yourself but it also means you are free to explore Poonhill in your own way. You need not carry huge supply of equipments. Poonhill trek is the lodgehouse trek. There are adequate lodges all across Poonhill trekking route that continues through woods of bamboos and blooming rhododendrons, culturally rich villages of Gurung ethnics and stone steps. Taking warm clothes are advised as Ghorepani and Poonhill are rather chilly places. 
If you are thinking of taking Poonhill trek without guide and if you are a foreign tourist, you need to arrange yourself for Annapurna Permit and TIMS card that will be required to enter the Annapurna National Park. You will head south west from Pokhara and take one hour of drive to cover 35km distance which will take you to Nayapul. 
Trek to Poonhill is the easy trekking. Poonhill trekking route continues through the places at lower altitudes. Infact, Poonhill that locates at 3210m altitude height is the maximum elevation that you will reach by joining onPoonhill trek without guide. 
Poonhill offers panoramic views of Annapurna I (8091m), Annapurna South (7219m), Dhaulagiri I (8167m) and Fishtail Mountain (6993m). Spring (March) is best to take Poonhill trek as you will pass through the colorful array of blooming rhododendrons and bamboos. Monsoon rain will have made the sky clear and you will get fine views of several mountains if you take Poonhill trekking in the month of march.