Garden Vegetables - How to Know Exactly When to Plant and Harvest Them
You don't have to rely upon the vague seed harvesting times predicted on seed packets. They're based upon an 'average' garden. Your garden is not average. Your plants will mature at different times from the same plants in the next county, or even garden.
How can you know exactly when your plants will be ready? Here's a great gardening idea to grow more vegetables. Calculate the Heat Units (HUs)!
HUs are one way that commercial growers know exactly when to roll out the harvesting machines. Do they read seed packets? No. We can easily use their method too. It's simply a matter of keeping a record, year to year, of how much thermal energy a given crop has received in a certain plot. And those HU records are unique to your garden and to the varieties you grow there.
Keeping a garden log is the first step
The first thing you do is set a Base Temperature and thereafter take note of the average temperatures each day. For cool-season crops like lettuce and brassica, fix the Base Temperature at 40oF. For warm weather crops - like tomatoes, beans, squash, sweet corn - set it at 55oF.
The base temperature is not critical. It's just an arbitrary reference point. But whatever it is, it must remain uniform in all subsequent measurements you make, so that you can keep and compare meaningful records. Now calculate your HUs.
The first time you plant a crop in your garden make a note of both the daily high and the daily low temperatures. And one to the other and divide by two. Now you have an average temperature. Subtract the base temperature from this number to obtain the HUs for that particular day.
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For example, suppose you've set out tomatoes in June. Over 24 hours, the first day has a high of 70ºF and a low of 60ºF. The average is therefore 65ºF. Take away the Base Temperature 55ºF you have determined for tomatoes and you're left with 10. This is the number of HUs.
Some beefsteak or other late tomatoes might demand as many as 1000 HUs to ripen outdoors. But lettuces will be ready to pick in around 500 HUs. But your own records over the years will tell you precisely how many HUs which crop and variety needs, in your own garden.
For instance, you could plant Siberian tomatoes - very early - just after the last frost day in your region. You'll know from your logbook that Siberian requires only 480 Heat Units. That's when the fruit will be ripe to pick.
Another virtue of this method is that you can plan profitably for succession planting. When you know from experience that your spinach will be ready to crop around 30th May you can have transplants of outdoor tomatoes ready to replace them at once. That's a lot better than consulting textbook dates, which were not written for your garden.
A lazy gardening way to check garden temperatures
Simply hang a high-low thermometer on a post clearly visible from your window. And equip your garden with some system of automatic irrigation. To check your heat units every day you'll just need binoculars! You won't even have to step outside to crop your first tomatoes, or any other plant, until they've reached the desired Heat Units.
Your Heat Units will be different even from your neighbors'. Yet despite even wide temperature fluctuations, month by month, in your garden you can be fairly sure of when every crop will be ready - just by doing the math. That's a great benefit for every busy gardener!
About the Author
Dr John Yeoman PhD is founder of the information network for natural gardening ideas, the Gardening Guild. Discover hundreds of original strategies to grow more food in your garden with less cost and labor in his practical book Lazy Secrets for Natural Gardening Success. Acquire it for free at: http://www.gardeningguild.org/lazy
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