Propagators help to increase your success rate with seeds. Some models have built-in automatic thermostats, and are perfectly adequate for most seeds. Other models have controllable thermostats, and these are suitable for more fussy seeds which require certain temperature settings. You'll find some of our propagators with small trays and some with full-size seed trays. Depending on the quantity of seeds that you wish to germinate, some customers prefer the small-tray models and others the larger-tray models.