If your website needs more resources than a shared hosting account can provide, or you would like to run an application not suitable for shared hosting, or you simply want a dedicated solution you can easily upgrade to a VPS. The VPS upgrade is available as an extra feature to your hosting plan.
To order Upgrade to VPS you need to be logged into your Customer Area first. From the Customer Area index please click on the icon Order Extras.

You will see a list of different extra features that could be added to your account. To proceed with the order, click on the Upgrade to dedicated solutions (VPS and Dedicated servers) link.

On the next page you can choose the desired plan. You can order it by pressing the Submit button for it.

SiteGround provides three VPS servers you can choose from. Every VPS comes with different features. You can review a VPS comparison chart and choose the one that best suit your needs from the link below:
Note: You can have 1 main website on each VPS and a different number of free addon domain slots depending on the VPS type - 3 with the Professional VPS and 5 with the Elite VPS.