In market gardening, maximizing space and time is the whole game. With limited beds and a finite season, profitability depends on succession planting: how many times you can flip a bed from one crop to the next.
The most intensive farms aim for four, five, or even six successions a year. This efficiency relies entirely on one critical number: Days to Maturity (DTM).
What Does DTM Really Mean
I have been farming for over two decades, and one of the first lessons I teach new growers is how to interpret the seed packet. There is often a misunderstanding about the Days to Maturity (DTM) printed on the back.
That number isn’t arbitrary, but it is standardized. It is often derived from trials conducted in controlled environments like heated greenhouses or regions with consistent climates. In those specific conditions, where variables are controlled, the number makes more sense.
However, the vast majority of small-scale growers aren’t growing in climate-controlled labs. We are in the field, in unheated tunnels, dealing with the reality of our specific seasons. For us, a static number cannot capture the dynamic reality of our farm.
Despite its variability, DTM remains the most critical data point for your planning. It dictates the rhythm of your entire season: when to start trays in the nursery, when to transplant into the field, and exactly when to expect the harvest to hit the wash station.
If we treat the standardized number as an absolute law rather than a baseline, we introduce friction into our logistics. A difference of a few days throws off the nursery schedule, leaves beds empty too long, or delays the cash flow we were counting on.
How Heat and Light Affects DTM
To plan better, we have to respect how plants actually grow. A vegetable reacts to energy, specifically heat accumulation and photoperiod (day length).
A crop planted in the shorter, cooler days of April will simply not mature at the same speed as the same crop planted in the long, warm days of July. A static number on a packet cannot account for this seasonality. As professional growers, we need to move beyond averages and understand the influence of our local climate.
Hyper Local Predictability
This is why we prioritized the new DTM algorithm inside Heirloom. We wanted to give growers a tool that adapts to their specific context.
Heirloom now personalizes the DTM based on your farm’s exact geolocation. By analyzing your local climate data (degree days and day length) we can estimate maturity dates with a much higher degree of precision.
At Heirloom, our mission is to equip small-scale growers with 21st-century technology that supports the way we actually farm.
By moving from standardized approximations to hyper-local data, we are helping to make this beautiful trade a little easier to manage and a lot more viable as a career. It is about having the right information to make the right decisions.