Posted: 06/08/2013 at 07:57
All toms can be classified as either early-season, mid-season or late-season varieties in terms of the time they take from planting out to maturity. With a bit of crossover, obviously. For unheated greenhouses and shorter growing seasons it's best to stick with the early- or mid-season (at latest) varieties.
As a very very very general rule of thumb:
EARLY - up to 60 days from planting out to maturity. You will find some varieties, like Stupice, of Czech origin, that will ripen earlier. The downside is that they have almost no flavour.
MID - 60 to 75 days from planting out to maturity.
LATE - anything from 75 to 90 (or more) days from planting out to maturity. Most of the larger beefsteak varieties fall into this category.
A bit of Googling will usually reveal a variety's category.