Frost Protection for your Atlanta and Georgia Garden and Citrus Trees
Fall is upon us, and in the coming weekend or next weeks we’ll likely have our first “real” freeze. Wait, I mean frost? Wait, what’s the difference? That’s right, we often use these interchangeably, but according to Michigan State University, “A frost is when we get a visible frost. A freeze is when the air temperature drops below freezing. Sometimes we get frost when the temperatures are above freezing and we often freeze without frost. It all has to do with the amount of water in the air.” To learn more about science you can check out MSU’s article.
So while here in our Georgia gardens we are blessed with a year-round growing season, we do have to give some of our fall vegetables a little extra lovin’ as the threat of frost grows - especially deeper into the winter months where we sometimes see extended hours and days of freezing temperatures. Like with everything, it’s a spectrum, and not all veggies are created equal when it comes to cold tolerance.
Here’s a very general outline below of what I prioritize in terms of protection with frost, but there is actually quite a bit of variation depending on the variety you get of each vegetable, how established they are, and whether it is a dramatic temperature drop and for how long. Look into the specific varieties you planted to see if they’ll hold up to winter temps.
How Cold Hardy are your Fall Veggies?
Lightly Cold-Hardy Fall Veggies: These can only withstand a light freeze of 29-32 without much or any damage. Prioritize protecting these when a risk of a frost is here especially if it is projected to be below 30 or if they haven’t experienced any cold weather before and are at risk of being shocked:
We plant all our lettuces and more tender fall / winter veggies together so it’s easy to quickly cover them as needed.
New Seedlings/Plantings. No matter what the type, they are going to be more tender until they are established!
Lettuce - certain varieties are better than others!
Peas - Flowers may get zapped during a freeze but plants will likely survive.
Most Asian Greens: Poc Choy, Chinese Cabbage etc.
Semi-Cold Hardy Veggies: Can typically withstand a moderate freeze of 25-28. Not as tender as those listed above and will survive mid to low 20s but will show signs of damage to the leaves and experience stunting. Again, very much dependent on the varieties and how established they are.
Arugula,
Broccoli
Cauliflower
Mustard
Chards
Cold-Hardy Veggies: Here in Atlanta and Decatur, I rarely protect these unless we’re getting an extended cold snap of low 20s or below over several days, which almost never happens. Even then, they typically bounce back.
Kale (Can survive in snow!)
Collards
Cabbage (but depends on variety, some will be more tender)
Spinach
Tatsoi
Carrots and most other root vegetables (the tops may die back, but their roots will survive and will likely come back for a spring harvest)
Cold Hardy Flowers: Here are some flower recommendations if you want to maintain a pop of color in the winter months, especially when we have more mild temperatures. If the flowers get nipped by a frost, just cut them back and new ones may arrive:
Pansies (There’s a reason you see them everywhere!)
Snapdragons
Calendula (Doubling as a wonderful medicinal too!)
Alyssum
Dianthus
If you haven’t already, we suggest goodbye to your summer goodies (think Tomatoes, Squash, Peppers, etc.) they are guaranteed to die back with a frost. Although you can certainly protect them over the next month, we don’t consider it worth the hassle or space as we get into late fall. The shorter days and less potent sun means the production of these vegetables are dwindling. Time to give your thanks for their abundance and lessons and say goodbye! Either swap them out for some greens or a cold hardy cover crop like winter peas and clover instead and get those beds ready for the spring.
Remember all of this advice is for the Atlanta gardens and Decatur gardens, so if you’re north of us know you may need to prepare for providing protection for more of your garden than we need to!
3 Planting Tips to prepare for the Winter Cold:
1. Planting the proper things at the proper time. It’s critical to know your growing zone, and therefore your average last frost. If you have an Atlanta or Decatur Garden, you’re likely either in zone 7b or 8a. As the temperatures trend warmer, that may change over the coming years, but for now that is where most of Atlanta lies on the zone maps. This means your average first frost is sometime in November.
If you’re outside of Atlanta, you can use the handy USDA Map which will let you put in your exact address, talk about precision! In fact, just a few blocks up is considered a different zone than we are, likely due to heat islands and other factors. Once you’ve identified your average frost date, consider how far in advance you will need to plant your fall veggies to either get a harvest or get them hardened off and established for the cold weather. Generally, I check the weather forecast and do not plant new fall seedlings when there is a frost risk in the next 14 days unless I am prepared to fully protect them.
That said, this is just an average and our weather patterns are less reliable than ever, so I generally recommend monitoring the weather for chilly nights beginning in mid October. This year is a great example of this - many of our clients in northern Atlanta like Buckhead and Brookhaven saw a very light frost in mid October.
Need some guidance around what to plant when in Atlanta and Georgia? We started a new Monthly blog series highlighting what we are doing and planting in the garden that month. Follow these links to find the planting guide and tips for August, October, and November. Keep in mind these aren’t hard set rules. My schedule rarely lines up perfectly with the “ideal garden planting times” and I often do late plantings in early November and just give my seedlings a little bit of extra love so they don’t get hit by a frost, so don’t fret if you feel like you’re too late to planting. Experiment and learn as you go!
2. Identify microclimates within your growing space.
After a full rotation around the sun growing in your space, you may notice something interesting! Certain parts of your landscape or garden get will get hit by a light frost and other areas go unscathed. This fun phenomenon is due to something we call a microclimate.
What is a microclimate? A microclimate is a small area that has a different temperature than the surrounding area - Think a cool, shady area on the north side of a building in the summer or a warm, sunny area on the south side of a building in the winter. In the latter example, the brick or stone of the building absorbs the heat of the sun during the day, and then radiates this heat back into the atmosphere once the sun goes down and the temperature drops, creating a warm microclimate that buffers the temperatures of the cold nights. Other examples of microclimates are parking lots/ areas with a lot of asphalt, swimming pools and large bodies of water, areas near large boulders, etc. In each example, an object with a high specific heat absorbs heat during the day and radiates that heat back into the surrounding environment at night. In these areas, the temperature could be equivalent to a higher USDA Hardiness Zone (such as 8b or 9a) while the broader area remains the typical hardiness zone (7b or 8a).
When you’re planting, whether it is a more tender fruit tree like citrus, or a more tender fall/winter vegetable like lettuce, identify these microclimates and plant strategically to help ensure success! We often build our client’s raised garden beds with a base layer of either slate chip or pea gravel, which can create a microclimate as well and put these gardens at an advantage in the winter months!
3. Planting more tender plants together. This is simply for ease of adding protection. In the next section, we’ll discuss how to cover your plants properly. If the plants that will need extra loving are in the same location, it will be much easier to cover, and therefore you’ll be more likely to do it! The saying work smarter not harder absolutely applies to gardening and your likelihood of success.
5 Ways to Protect your Plants from the Cold:
Already planted? Don’t worry! There are plenty of options for you to protect your plants moving forward, but now is the time to identify whether you have the necessary information and materials.
Monitor the Weather - This seems obvious, but cold nights will sneak up on you especially early in the season! Check those projected lows each day beginning in October or you may regret it. With our weather too, we may see warm days in December and then BOOM! A cold snap that will shock your plants without protection, so it’s good to remain vigilant.
Row Covers: When we see temps at 30 or below (use a mid-weight row cover from @johnnys_seeds that we place on each bed using hoops for our semi-cold hardy crops other than broccoli/cauliflower. For home garden size or for quick delivery, these agfabric ones on Amazon work as well. We create hoops in our beds either using PVC pipe or 10 gauge galvanized steel you can source from big box stores and cut and bend to size.
In a pinch you can use whatever you have at home like sheets, towels, or burlap to cover them. Try to elevate them over the plants so they’re not touching using hoops, stakes, or whatever is around. Secure them with landscaping staples, clips, rocks, or whatever you have around. They are definitely susceptible to flying around if it is windy. Be creative! Due to warmer day temps, you almost always only need to cover them at night and we recommend removing them during the day if you can so they get full sun.
Be careful with plastics - this can actual damage the plants if it freezes and is touching your leaves. Check out one of the ways we’ve done it in the past:
Cold Frames: While I don’t think this is super necessary in an Atlanta garden, some folks create more permanent Cold Frame structures and they create a bit of a greenhouse effect. You would need to be careful about lifting them on warmer days, so that the plants don’t get burned or too dried out. You can find cold frame youtube instructions here.
Watering: Thirsty plants are stressed plants and are thus more susceptible to damage from cold snaps, so make sure to water your plants in the days leading up to a frost. Watering the day before can also be beneficial because water also has a higher specific heat, meaning it will maintain its higher temperature longer and help create warmth for the plants. Just make sure not to get the leaves wet or water them early enough so that it evaporates.
Mulching: Adding mulch or fresh compost helps protect the roots of the plant or tree which help with its general survival, but does not protect the leaves so make sure to use the other techniques above as well.
Protecting your Citrus Fruit Trees
For the first three years after you have planted your citrus tree, regardless of the type, you will want to make sure to give it a little extra care and protect it when temperatures dip into the 20s.
Here is our ranking of the citrus trees we sold at the snackyard sale in terms of cold hardiness:
Not Cold-Hardy:
Lemonorlime (or any lime tree!)
Semi Cold-Hardy: These trees are on the same cold-hardy rootstock as our satsumas, so may hold up to a mild winter if planted in a micro-climate, but we generally recommend keeping these in a pot in and bringing them inside during freezing temperatures. If you do plant them outside, let us know how they do! Just make sure to give them lots of extra protection!
UGA Grand Frost Lemon
UGA Sweet Frost Grapefruit
More Cold-Hardy: These can be planted outside in Atlanta, but do your best to plant them in a micro-climate when possible and give them extra protection the first three years after planting for a better chance of production.
Satsumas (all varieties)
UGA Sweet Frost Tangerine
Loquats
Kumquats
For these first three years after planting, regardless of variety, when temperatures drop below freezing (32 degrees), you will want to provide some sort of frost protection for your citrus. This will help them get established and give you a higher chance of production next season and in the years to come.
WATER & MULCH: Just like veggies, watering and mulching your trees with mulch or woodchips will help keep the soil warmer and protect the tree roots. If you see freezing temps on the radar, begin deeply watering a day or two in advance.
PROTECT THE TRUNK: You can easily wrap the trunk in burlap or even surround it with bricks or stones - creating ga little microclimate as outlined above. See the youtube video below for an example of this.
FROST BLANKET: ESPECIALLY the first year, when temperatures drop below 32, you’ll want to wrap your tree in a frost blanket - readily available at most hardware/nursery stores or online. These blankets should ideally be covering the trees all the way to the ground, this helps maintain the soil temp and create more of a humid atmosphere - especially if you watered earlier in the day. Make sure to secure them as they will easily blow off with a bit of wind.
If freezes are just overnight, this method will be just fine, and you can simply remove the blanket during the day when temperatures rise, to avoid overheating.
If you’re ordering online they’re sometimes referred to as a “frost jacket.” When you’re ordering online, make sure you are ordering winter-weight fabric as opposed to one that just protects from insects and pests.
*We do not recommend using plastic materials, which can freeze and if touching any of the tree or it’s foliage will actually cause more damage.
FROST COLD FRAME: However, if there is a multiple day stretch of freezing temperatures, you will want to consider building a bit of a frame either with wood, pvc pipe, or other materials around your tree to wrap the frost tarp or blanket around, this way the branches and leaves will not be crushed under the tarps pressure for that long and there is proper air filtration.
Here’s a great video on how to create a PVC frame and a microcilmate with bricks:
Bringing Fruit Trees Inside for the Winter: You should bring in the lemonorlime we sold at our snackyard sale as well as the UGA Grand Frost lemon and UGA Sweet Frost grapefruit trees unless you are feeling experimental. Those that will go indoors for the winter should be grown in a container. This will allow you to bring it inside more easily. Choose a container that is made of a lighter weight material, i/e not ceramics or terracotta. Most lightweight containers made from plastics are also non porous, so the soil will not dry out as quickly as a porous material like clay. The container should have adequate drainage on the bottom, and you’ll want to set the container on a tray to catch all the drained water.
Consider putting your container on a platform with wheels so it is even easier to move around. You will want to acclimate your citrus to indoors before finalizing its move. This can be done by bringing it in and out over a few days, so there’s less of a shock to the new climate. You will reverse this process in the Spring when it’s time to bring it back outside!
Indoors, situate your citrus where it will receive the most sunlight, ideally at least five hours. Try not to place it in a room that is especially drafty. Citrus enjoy a high humidity. With heaters on throughout the Winter, our homes dry out more quickly than usual, so you will want to mist the plants regularly, or create a more humid environment (pebble trays, humidifiers, etc).
DON’T STRESS
Did your plants or trees get zapped? Don’t fret! Often times a single frost or shock won’t kill a tree or plant, although it may limit production or growth for the following year. Make sure they are protected next time, and although they may have been stunted or some branches or leaves were damaged, they are often more resilient than you think. Give them until early spring to come back. You can always prune back dead branches, etc. at that time.
Overall, enjoy the reprieve of this slower, less buggy, less weedy season. A little extra care will ensure you have a harvest year-round, but if a cold spell catches you by surprise, we promise it’s not the end of the world (althought sometimes it certainly feels that way!) Take it as a sign to take the much needed break that this fall and winter are offering you. We know we will!
