By Jim McCausland, Sunset Magazine

Killing frost is the horticultural version of The Grim Reaper. Usually stealing into the garden on a calm, clear, dry autumn night, it cuts down all remaining summer fruits and flowers. It is worth noting on your calendar because it marks the end of the growing season, which began with the last killing frost of spring.

Once the growing season starts, you plant beans, corn, cucumbers, eggplant, melons, peppers, squash, and tomatoes. Then you start counting.

When the seed packet says you have an 85-day tomato, or a 110-day pumpkin, it’s giving you the number of days between planting and harvest. But your growing season better be significantly longer than that.

Here’s why.

•For starters, actual days to harvest depends on location. If you’re growing warm-season crops in a climate that gets warm days, mild nights, and plenty of moisture, plants mature fast. But if you’re growing the same varieties along the coast, where summers never get very hot, plants mature very slowly. Many national seed sellers assume optimal growing conditions for their days-to-harvest numbers. So a tomato that might mature in 85 days in Ohio might take 125 days to mature along the mild Oregon Coast.

•Days to harvest clocks the time from planting to the day your pick your first fruit. But plants can bear for weeks or months after that first fruit. So an 85-day tomato could keep producing fruit from day 85 to day 145. That means you really need a 145-day growing season to let you get the most from your plants.

The best way to calculate your garden’s growing season is by writing down first and last frost days (start now!) The second best way is by looking up your town’s historical weather information on one of the National Oceanic and Atmospheric Administration’s regional climate center databases. These vary widely in ease of use, but you're in luck if you live in the West, which has a complete, easy to use climate center. Navigate to your state, your city, then click on the link to "Freeze Free Probabilities," which gives you growing season information.

You can also get map-based information from the Internet Accuracy Project.

I could close with warnings and disclaimers, but you know the drill: nature does what she wants, when she wants. Just get to know her better by writing down last and first frost dates as they occur in your garden, and you'll be a better gardener for it.

By Julie Chai, Sunset associate garden editor

If you love Michael Pollan’s work as much as we do, you’ll want to see The Botany of Desire, a TV special based on Pollan’s book of the same name.

Focusing on four crops—apples, tulips, cannabis, and potatoes—the show explores how the plants may very well be exploiting us instead of the other way around. And it’s packed with interesting factoids. Some of my favorites (that won’t spoil anything for you if you’ve not read the book):

• Most apples in the wild aren’t sweet, and are basically inedible. (And Johnny Appleseed isn't quite the person you thought he was...)
• During the Dutch “tulip mania” in the 1600s, tulips were valuable commodities that signified wealth—bulbs of one variety cost $10 to 15 million each in today’s dollars.
• Cannabis extract was found in many over-the-counter medicines and was basically available anywhere before states starting outlawing it in the early 1900s.
• We might think we have a lot of choices between Idaho russet, Yukon gold, fingerling, and red potatoes. But in Peru, where spuds were first domesticated, people still cultivate more than 5,000 varieties.

The Botany of Desire airs on Wednesday, October 28 at 8 p.m. on PBS.