What is a cool-season?
The cool season begins when the day time temperatures come to 75F (24C), and night temperature 60F (15C) or less. In other words, it starts in fall and extends till early spring, ending with the last frost date.
While the calendar shows that the beginning of Fall is September 21, each geographical region has a different natural starting date. In the north, the cool season starts early September, while in the south summers can stretch till December.
For gardeners, it is best to look up the growing zone, which determines the first and last frost dates. Approximately, the cool growing season starts eight to six weeks before the first frost and ends with the last frost date.
Click here to find your zone in the USA.
After a busy summer, Northern gardeners put their gardens to bed for winter hibernation. In the south, gardeners gear up for their best growing season yet. The cool temperatures and more rain bring back life to the garden.
In Central Texas, warm-season garden overlaps with the cool-season garden. The average first frost date is Dec6, which is enough time to have a second round of tomatoes, peppers, eggplants, cucumbers, and bean harvest starting September. While those crops are having a second chance to thrive, it is time to start cool-season seeds indoors.
What are cool-season Vegetables?
You might be surprised at how many vegetables you can grow in the cold season garden. The list below is divided into groups according to their common use.
- Root vegetables: beets, carrots, turnips, radishes, and potatoes.
- Heading vegetables: broccoli, cabbage, cauliflower, choy…
- Leafy vegetables: mustard greens, Asian greens, kale, lettuce, spinach…
- Herbs: celery, parsley, cilantro, dill…
- Alliums: onions, garlic, spring onions, chives, shallots, and leeks.
- Other: broad beans (fava beans), artichokes, fennel, peas, and asparagus.
How to prepare for a Fall/winter garden?
Get rid of any diseased or pest infected plants from the summer garden. Do not throw them in the compost, throw them in the trash or burn them.
Most summer crops are heavy feeders, at the end of the season, the soil is depleted from many nutrients. Add compost or well-rotted manure and work into the soil. Give a week or so to settle and cool down before planting.
Soil settles and gets compacted through time. Lightly till the growing areas enough to get some air into it and loosen it up. No need to use a tiller for this, a light tease with a garden fork will do the job.
If you mulched the growing bed in the summer, it is a good time to renew it or add to it. The lower layer has broken down during the previous growing season.
- It is a good time to build structures such as trellises, hoop house frames, or cold frames. Don’t wait until the cold weather hits to make them.
- Have shade cloth ready to protect your new plants in case the hot weather lingers.
- Prepare your barrels for harvesting rainwater.
- Have a floating row cover on hand for those sudden frosty nights.
- Keep an eye on pests, some warm-weather bugs might still be lurking around and they might cause serious damage to the small plants.
When to start seeds in the cold weather?
The common practice is to start seeds six to eight weeks before the first frost. In Central Texas, start them in September to have them ready for planting by the end of October. At this time, you have less risk of heat stress, which can hinder your cold season crops’ growth.
Start the seeds indoors under grow-light or on a bright sunny window. You can also have them in a shady spot outdoors, where they only get early morning sun. But having them indoor has better results than outdoors.
Here a list of plants you can start from seeds in September in Central Texas and any mild winter region:
- Cabbage (all kinds)
- Cilantro ( I prefer direct sow)
- Greens (Asian, Chard, kale, turnip, spinach..)
- Head Lettuce
- Parsley (I prefer direct sow)
To ensure continuous production, start your seeds in batches, spacing them two to three weeks apart.
What is the difference between frost and freeze?
A frost is a sparkling layer we get on surfaces in the cold weather. Cold air holds less water than warm air, so when humidity approaches 100%, condensation occurs in the form of frost. And temperature does not have to be at a freezing point for frost to happen.
When air temperatures drop below 32F (0C), that’s called freezing. Most of the time we get a freeze with no frost. There are three types of freeze:
- Light freeze in which temperatures are between 32G-29F ( 0C, -2C). This kind of freeze kills only tender plants.
- Hard freeze where temperatures reach 28F- 25F (-3C, -5C). This one can damage a wide variety of crops.
- Severe freeze has temperatures below 24F (-4C), and it can be very damaging to vegetation.
What crops survive frost?
The majority of cool-season vegetables can survive a frost and light freeze. It might cause some discoloration on lettuce, parsley, and cilantro but that’s about it. They recover to their normal state as soon the sunshine hits them. Brassicas, which is cauliflower and family, take frost very well. They even develop a better taste after a frost or light freeze.
How to protect growing vegetables from freeze?
Protecting the garden from freeze is as simple as laying an old bed sheet or a fleece on the plants. Here are some useful tips for effective protection:
- Put down the cover before the wind picks up, for an easier job.
- Use fabric or specialty row cover instead of plastic. The latter may cause leaf burn and damage the plants.
- It is best if there the cover does not touch the plants to prevent frost burn. Make hoops to create tunnels as support.
- Use heavy-duty clamps and rocks to hold the cover in place.
- Keep the cover on, as long as the freeze lasts. Don’t worry about sunlight not getting to the plants.
- Water your plants thoroughly if it hasn’t rained, to create a protective shield for the root system. Frozen dry soil can cause the roots to freeze.
How to deal with pests in fall and winter?
Fortunately, there are not as many pests to deal with in the cold season. Some of the bugs are leftover from the previous season, that’s why cleaning the garden is essential.
They are tiny green or black insects that suck on the leaf sap. They thrive in the hot weather, but they can devastate your fall garden if the temperatures are still warm.
Stay on top of them by regular inspection under the leaves and the new growth. Apply a strong jet of water to wash them off. In case of an infestation, use an organic oil-based bug spray such as neem oil or peppermint oil spray. Treat the infected area every two days to get rid of them.
The good news is that they do disappear when temperatures drop considerably, to only show up later in the spring.
Similar to aphids, mealybugs linger in the garden as long as the weather is warm. They are small white fuzzy insects that feed on the new growth. They also form a sticky cottony blanket over the plant. Try to control them as soon as you notice them before they do cause great damage.
Dip a cotton swab in rubbing alcohol and use it to wipe the mealybugs off of the plants. If there are too many of them, make a solution of one-quart water, one cup rubbing alcohol, and a few drops of liquid soap. Spray this formula over the infested plants, twice a week until you get rid of them.
These green worms are the larvae of the white moth. They feed on the brassica leaves, which they can strip down overnight. Start monitoring them by checking under the leaves as soon as you put your crops in the ground. Handpick them if the infestation is not so bad.
You can use a physical barrier, such as mesh cover. The holes in the cover are small enough to block the white moth from laying its eggs on the plants.
If the preventative steps didn’t work, use an organic insecticide called BT or Thuricide. It is a bacterium-based product that kills the caterpillars when they digest it.
Snails and Slugs
Snails and slugs can be devastating to the cold-season garden. They mostly show up on rainy days, they leave a trail of dried slime on the leaves. Handpicking is the first step to control them.
Setting up traps is another way to catch them. Fill a used tuna can with any sweet drink, then sink it level in the ground near the problematic area. Leave it overnight, the next day it should be full of drowned slugs and snails.
The last solution is to use an organic snail killer. The product is called Sluggo, comes in a form of granules made out of semolina and BT powder. Sprinkle some over the area, and watch the dramatic drop of snail/slug population in a few days.
Pillbugs or rolly-pollies are among the decomposing creatures. Many think that they only feed on dead material, and do not harm new plants. But they do feed on the woody part of the broccoli and cauliflower stems. And when they are in numerous numbers, they do destroy the vegetable garden.
Sluggo Plus is the product that takes care of them. Similar to the Sluggo which kills snails and slugs, Sluggo Plus kills the pill bugs. Sprinkle some on around the vegetables to save them.
Cutworms live in the soil and feed on the stem of the vegetables. They chew on the stem base till they cut it off, hence the name. Wrap the stem with tin foil to create a barrier. You can also sprinkle some BT (Thuricide) powder around the plants to kill them.
Cool-season garden diseases
Fungi and nutrient deficiency are the main causes of diseases int the cool-season garden. Prevention is the most effective way to deal with them.
- Make sure to clean the garden well from last season’s remains.
- Discard all sick plants and fruits in the trash.
- Add compost and organic fertilizer to replenish the soil.
- Practice crop rotation to discourage soil-borne diseases from spreading.
Most common diseases are:
The hollow stem on broccoli
This is a physiological problem that causes the broccoli stem to be hollow. It is more of an aesthetic problem and does not affect the harvest. Planting disease-resistant varieties is the best practice to prevent it.
Click here to learn more about it.
Rust is a fungal disease that shows as brownish, reddish colored spots on legume plants. Proper cultivation practices are key to have it under control. Plant disease-resistant varieties and remove infected leaves or pods as soon as you notice it. You may also use a copper-based fungicide for a treatment.
This is a fungal disease that attacks potatoes. Mild winters generally favor the spread of the spores. It manifests as yellow spots on the leaves that shrivel and turn brown fast. The fallen foliage contaminates the soil spreading the disease to the tubers under the ground.
- Discard the top of the plant or burn it.
- Harvest any potatoes that have no sign of infection and get rid of the infected ones.
- Don’t keep the potatoes to plant the following season.
- Practice crop rotation and don’t plant potatoes in the same bed for at least three years.
Another fungal disease that occurs when the weather is humid and warm. It attacks peas mostly at the end of winter. No need for treatment, since it comes at the end of the pea harvest. Discard the plant once it is done producing.
Don’t forget the flowers
Adding flowers to the vegetable garden breaks the dominant green color, which can be boring to some. It also attracts a variety of flying insects, making the winter garden lively.
What flowers grow in the cool season?
Aster is a beautiful fall bloomer. It comes in different colors such as blue, purple, pink, and white. Very attractive to bees and butterflies, and as a bonus, it is drought-resistant.
Chrysanthemum is a popular fall bloomer with its breathtaking bronze, red, white, and yellow colors. It grows well in pots as well as flower beds. I like tucking them in between the cabbages. Its mounding growth habits blends well with the shape of the cabbages. They last a while in our Southern garden, and bloom several times in fall, mid-winter then in Spring.
Calendula is a beautiful multilayered petal flower. It comes in different shades of orange and yellow, which make them stand out in the garden. They bloom all season long from fall through the end of spring.
Pansies and violas are two very similar flowers. They make a better impact when planted in clusters at the borders.
Osteospermum, also known as African daisy, is a prolific mid-winter bloomer and looks great in borders. It also comes in an array of gradient colors white, yellow, purple, and orange.
Ranunculus or Persian buttercup is a rose-like flower. Plant the corms around October for late winter early spring show.
Snapdragon comes in two different types. Dwarf mounding snapdragons which bloom fall through spring. Tall snapdragons that bloom from late winter to early summer.
Click here to learn more about winter blooms.
Be patient and enjoy your garden
Don’t get discouraged if you missed protecting your garden or loopers destroyed a cauliflower plant. There is always a second chance in life. Gardening is all about patience and perseverance, after all.