When can I pick my tomatoes? Will these melons ripen in my short growing season? If I plant these flowers from seed, when will I have blooms?
“Days to maturity” is one of the most important factors in determining what we can grow in our high altitude gardens. Technically, this number tells the gardener how long a particular crop or variety takes, on average, to yield a harvestable crop. However, it’s all a bit fuzzy.
For example, most catalogs or seed packets list days to maturity for vegetables, but only a few mention how long it takes for flowers to bloom. Are they talking about the length of time it takes for a plant to mature a crop from seed—or transplants? And how old a transplant? In addition, when you compare catalogs from different parts of the country, days to maturity vary even for the same kind of tomato or bean. Clearly this concept is more complicated than it first appears.
Part of the confusion is because there are no universal standards. Each seed company comes up with a number based on the results of their own trials. It stands to reason that plants in a trial garden in a warm climate will mature more quickly than that same variety planted at a higher altitude or in a more northern climate.
It isn’t just the daytime highs that make a difference. Nighttime temperatures are very significant. In areas with relatively high humidity, or at low elevations, nights retain much of the day’s heat, and plants continue to grow. Along Colorado’s Front Range, however, nighttime temperatures regularly dip into the 50s, even in the middle of the summer. Most heat-loving crops simply stop growing and wait for things to warm up.
We can easily see that this is the case. Early Girl is a popular tomato variety for short summer areas. Park Seed, located in South Carolina, lists Early Girl as taking 57 days from transplant to the first ripe tomato. Territorial Seed Company find that this same variety takes from 75 to 80 days in their trial gardens in Oregon. The main difference is nighttime temperatures.
In my garden at home, I’ve learned to give corn, tomatoes, and other warm season plants approximately twice as much time to mature as what is listed in most catalogs. (Of course, this varies considerably from year to year, along with the weather.) Since my growing season only averages 125 days, that means if I plant a tomato listed at 64 days, I may get lucky and harvest one ripe tomato before the snow arrives. You can see why I search out the earliest varieties possible!
When do the seed companies start counting? While some suppliers tell you how they measure, others leave you guessing. Thankfully, most companies make the same assumptions. When it comes to tomatoes, peppers, eggplant, and other traditionally transplanted crops, the days to maturity number starts when they are planted outside. Additionally, they assume you are setting out seedlings that are six to eight weeks old.
On the other hand, beans, carrots, and lettuce, among others, are typically seeded directly into the garden. In this case, maturity is counted from the date of seeding. While I usually start cabbage, broccoli, and other cole crops indoors, those vegetables are also counted from the time the seeds go into the ground.
As I mentioned earlier, most companies provide us with days to maturity for vegetables, but not for flowers. I find this very frustrating, so I was particularly delighted to discover that the Vermont Bean Seed Company lists “days to bloom” for many of their flower seeds. Most of the time, however, we have to figure it all out on our own. I start with an online search. If that doesn’t yield results, I ask other gardeners in my area. Perhaps one of them has tried growing that particular cultivar. Local greenhouses may also be helpful. When all else fails, I try a small trial planting.
In fact, it pays to keep records from year to year, whether or not the seed company gives you their “days to harvest” estimate. Over time, you’ll learn how long to allow for each crop or variety you grow. That will give you the best answer of all—one that applies specifically to your own garden.