Last Frost Date: What it Means to Your Garden

The most important factor in determining when to plant any vegetable in your garden is the “LAST FROST DATE” in the spring, and the “FIRST FROST DATE” in the fall for your area. These dates for a given area are based on historical weather data from that area collected over a 30 year period and compiled by the National Climatic Data Center from over 5,800 Weather Monitoring Stations throughout the United States.

For each Weather Monitoring Station, a FREEZE DAY is any day in the year that the temperature reaches 32°F or below. A FROST DAY is any day in the year that the temperature reaches 36°F or below.

So why worry about FROST DAYS more so than FREEZE DAYS? Well, a Freeze is what will kill many plants. But, Weather Monitoring Stations are typically mounted four to six feet above the ground. During clear, calm, and cold nights the temperature at ground level, where your garden is, can become much colder and even freeze. So we’re just trying to play it a little safer by focusing on FROST days.

In the spring, as temperatures start to warm, the LAST day of the year that a FREEZE DAY occurs is considered the LAST FREEZE DATE for that year. As the temperatures continue to warm, although no more FREEZE DAYS may occur, the LAST day of the year that a FROST DAY occurs is considered the LAST FROST DATE for that year. Usually about a week or two after the LAST FREEZE DATE.

The LAST FROST DATE for your area is the day of the year, based on these 30 year averages, that there is only a 10% chance that there will be a FROST on that day. So, at least statistically, you should be safe to plant ON or AFTER this date.

In the fall, as temperatures start to cool, the FIRST day of the year that a FROST DAY occurs is considered the FIRST FROST DATE for that year. As the temperatures continue to cool, usually about a week or two later, the FIRST FREEZE DAY of the year will occur.

The FIRST FROST DATE for your area is the day of the year, based on these 30 year averages, that there is a 90% chance that there will be a FROST on that date. So again, at least statistically, you will want to have completed your harvest ON or BEFORE this day.

Remember, although statistically accurate, you are really just playing the odds with these dates. It’s kind of like going to Las Vegas, but instead of gambling with your money, you put your tomato plants up on the blackjack table. (Editors Note: For your own safety, DO NOT attempt this in any gaming establishment.) Before planting you should ALWAYS check your local weather to see if a frost or freeze is in the forecast.

The National Climatic Data Center has recently released an entirely new data set, this one collected between 1981 and 2010. With this data, we’ve created a new and improved way for finding the FREEZE and FROST DATES for your specific area.

Enter your 5-DIGIT ZIP CODE in the calculator, then click on the FIND IT button. The FREEZE and FROST DATES for your area will then be displayed in the RESULTS section. If you want to look up another location, Click the RESET button, and start over.

I hope you find this information helpful, and I wish you Happy (freeze damage free) Planting.

Data Source: National Climatic Data Center

Crop Rotation in the Home Garden

Crop rotation is the practice of growing different crops, on the same land, in sequential planting cycles ranging from 2 to 8 years. Farmers have used crop rotation for centuries as a means of reducing crop lose due to disease and insects, as well as replacing essential nutrients, used by plants while growing, back into the soil. It was first mentioned in early Roman literature, and George Washington Carver is widely credited with introducing crop rotation to the United States by rotating peanuts, sweet potatoes, and cotton.

Insects and Disease
Soil borne pathogens, and insects, that attack one member of a plant family frequently will infect or attack other plants in that same family. Planting similar plants in the same location, year after year, tends to make the soil in that location much more prone to the diseases and insects that harm those plants.

Soil Nutrients
Different crops take varying amounts of different nutrients from the soil as they grow and produce fruit or vegetables. If similar plants continue to be planted in the same location year after year, the nutrients in the soil inevitably become unbalanced to the point where even the addition of fertilizers may not entirely correct the deficiency.

Preferred Method
There is no hard and fast rule as to which plants should be planted after another when practicing crop rotation, whether in the farmer’s fields or in the home garden. The most effective, and easiest crop rotation system involves grouping vegetables into six ( 6 ) different groups, each of these groups having similar insect, disease, and soil nutritional content characteristics. Never plant a vegetable from the same group, in the same location, two years in a row. Waiting three years before planting a vegetable from the same group is even better.

For example, if this spring you plant Tomatoes, a Group III plant, in a particular spot in the garden, you could plant Broccoli, a Group II plant, in that same spot this fall, and then Cantaloupe, a Group I plant, in that spot next spring. By sequentially planting warm and cool season crops from different groups, you will maximize your garden’s production while maintaining good crop rotation practices.

Here is a Garden Planning spreadsheet that I use with my raised beds utilizing “square foot gardening”, to help keep track of what has been planted, where it was planted, and when. Use it as it is, or feel free to modify it to better meet your particular needs.

Although it takes a little advance planning to implement crop rotation in your home garden, the increased health and production of your vegetables will make you glad to put the effort into doing so.

Crop Rotation Plant Groups
[ Group I ]
• Cucurbitaceae (Gourd Family)
– Cucumber
– Watermelon
– Cantaloupe
– Honeydew Melon
– Summer Squash
– Winter Squash
– Pumpkin

[ Group II ]
• Cruciferae (Mustard Family)
– Cabbage
– Broccoli
– Cauliflower
– Kohlrabi
– Collard
– Kale
– Brussels Sprouts
– Chinese cabbage
– Turnip
– Radish

• Chenopodiaceae (Beets Family)
– Swiss Chard
– Spinach

• Compositae (Sunflower Family)
– Lettuce
– Globe Artichoke
– Jerusalem Artichoke

[ Group III ]
• Solanaceae (Nightshade Family)
– Tomato
– Pepper
– Eggplant
– Potato

• Convolvulaceae (Morning-glory Family)
– Sweet potato

• Malvaceae (Cotton Family)
– Okra

[ Group IV ]
• Alliaceae (Allium Family)
– Onion
– Garlic
– Leek
– Shallot

• Chenopodiaceae (Beets Family)
– Beets

• Umbelliferae (Parsley Family)
– Celery
– Carrot
– Parsnip
– Parsley

[ Group V ]
• Gramineae (Grass Family)
– Sweet corn

[ Group VI ]
• Leguminosae (Pea/Bean Family)
– Snap Bean
– Pea
– Cowpea
– Black-eyed Pea

Plan your spring garden

As we turn the calendar page from February to March, signs of the approaching spring are becoming more and more evident for some, while many of us are still under several feet of snow. Here in Texas, within the space of a few days, the weather has gone from a spring-like 78 degrees to a snow and ice storm.

Get Started
As our thoughts also turn to spring, now is the time to take stock of our yards and make plans for our warm season garden. So grab a cold drink and find some shade, or huddle over a hot cup of cocoa and put on a warm sweater depending on what these unpredictable mornings hold, and let’s get started. By planning, and where appropriate planting now, your landscape and garden will be ready to flourish in the months to come.

Clean it Up
The best way to start getting your garden ready for spring is to clean it up. Remove any dead or spent plants from the garden and, if they are not diseased, add them to your compost pile. Pull any weeds that may have started to take hold. Once you’ve cleaned up, you will want to amend your soil by adding compost to garden beds and tilling it in. This will help replace nutrients taken up by the previous planting.

Draw a Plan
Grab a pencil and some paper and draw a diagram of your yard. You don’t need a degree in art or an expensive software program to draw a rough sketch of your landscape and garden plan. If you have the original survey from when you bought your house, make a copy of it and use that as a starting point. If not, just make a rough sketch of the footprint of your home. Draw in existing landscape features, and planned garden areas. Indicate which way is north and make note of any shady or poorly drained areas.

Plant What you Like
When planning what vegetables to plant, it’s easy to get carried away and want to grow everything under the sun. It’s always fun to try something new, but focus on growing what you really like. Make a list of the warm season vegetables for your area that your family likes and rank them from most to least liked. Plan on planting what you like. If no one in your family likes lima beans or squash, for example, then plan on planting more of what is most appealing.

Can, Store, or Eat
Once you know what you want to plant, decide what the intended use for each vegetable and herb will be. Do you plan on canning enough to last through the winter? Will you be freezing or dehydrating? Or, will you just eat and enjoy what you harvest this spring and summer. Different varieties of many vegetables are better suited to a specific purpose such as canning. Do your research.

Don’t Forget the Flowers
When planning your vegetable garden, it’s easy to overlook the importance of flowers. Look at your landscape as a whole and determine what native or locally adapted flowers are best suited to the different areas of your yard based on their color, size, water requirements, and the amount of sun needed. Flowers are an attractive, and highly effective way of drawing pollinators into the yard and garden.

Add New Beds
Now that you know what you will be planting and what your harvest will be used for, you can determine how much of each variety you should plant. Look at your existing bed space and any areas of your yard that you may want to convert to garden beds. For new beds, avoid low-lying, poorly drained areas. Clear the ground, till and amend the soil now. Better yet, try raised beds. They are a great way to avoid having to deal with the rock filled soil around here, and will maximize your harvest in the space available.

Order Seeds Now
As soon as you’ve determined which vegetables, what varieties, and how many of each you will be planting, go ahead and buy your seeds now. Be sure to check out our comprehensive Seed Source Guide 2015. This will ensure that you get exactly what you want and have them ready to plant when the time arrives; however, wait until just before planting to purchase transplants.

Know When to Plant
One of the most important factors in having a successful home garden is planting each vegetable at just the right time. Check with your local AgriLife Extension Service or our How Do Gardener Planting Guides.