Roger Mercer: Tips for growing kale in containers

Dear Roger: I’m a kale freak. I can’t grow them in my apartment. Will they grow in pots on my balcony? — Patricia Harrison, Wilmington

Dear Patricia: You absolutely can grow fine kale in a pot. Kale grows big and needs a big container. Use at least a 3-gallon pot. Or try a 5-gallon pail, or be creative and go for three plants in an oak half-barrel.

You may sow seeds now or in early spring, late March through April, in your containers on the balcony. They’ll come up in just a few days. In two weeks, they’ll start to have true leaves. That’s the best time to thin the seedlings. Leave the biggest two or three seedlings in each pot. In half-barrels, leave three or more groups of two or three.

Your young kale seedling may be damaged by sudden and extreme cold snaps. So start the kale in small pots that can be easily moved indoors during any sudden dip below 20 degrees Fahrenheit. Move the plants outdoors as soon as nights warm into the mid-20s. Leaving them indoors too long will destroy their cold resistance.

Move strong young plants to larger pots after a few weeks. Despite the large pots, the plants will need daily watering when they reach full size in the heat of spring or summer. You may pick a few young, tender leaves to add flavor to salads all winter, but leave plenty on the plant to produce good greens for boiling with fatback or olive oil.

Late-started kale produces great fall and spring crops with huge leaves and remarkable flavor.

Good potting mix is worth more than its price in increased production of big, sweet leaves. Some fertilizers contain slow-release nutrients that last for several months.

If you grow kale in the ground, you don’t need potting mix, just a good 3- to 4-inch mulch to protect soil moisture in summer and soil temperatures all year.

Kale grows best with plenty of nitrogen. In pots, give plants frequent watering with half-strength soluble high-nitrogen fertilizer, or use coated, slow-release fertilizer once or twice depending on whether it’s a three-month or six-month fertilizer. 

In garden soil, mix in a tiny bit of organic fertilizer before planting and side dress with more each month.

Remember to take into account the nitrogen that may be included in your potting mix. You may not need any extra nitrogen for the first few months.

Lots of sun will help your plants be as productive as possible. A northern exposure will produce wimpy plants, but you will still get some pretty tasty greens. Sun-grown kale are very high in vitamins. They have high amounts of vitamin K, and good amounts of vitamins C, A and B6 and the minerals manganese and calcium.

A south-facing patio is ideal.

Start the seeds outdoors. Seeds started indoors this time of year may be damaged by freezing when they are moved outdoors. Seeds started outdoors will generally take care of themselves, except when they are less than a month old.

Freezes down into the mid-20s in winter may burn the leaves somewhat, but a rapid recovery can be expected.

Freezes down to 5 degrees may kill plants to the ground, but they will generally recover vigorously in time and make plenty of leaves to eat. A loose mulch of pine needles 6 inches to a foot thick will help protect the plants.

Dear Roger: I stored some daylily seeds from my garden. I am drying them, and I have a quick question. I looked on the Internet and, of the several pieces I read, the directions said to soak the seeds and refrigerate from three to eight weeks and then plant. One site said to dry the seeds and plant directly in a good potting medium, keep moist, and in the bright sun (for energy).

Which is best? — Joni Martin, Laurinburg

Dear Joni: Thank you for your faith in my advice. I do the following:

• Pick seeds when pods turn brown and begin to crack open. Shell them out in a day or two.

• Let them dry on the porch outdoors for at least two days. Toss out the seeds that have nothing but air in them. And eliminate the squishy ones, too. Give them a light squeeze. If they are not firm, throw them away.

 I eliminate the “air seeds” that contain nothing by putting the seeds in a shallow bowl. I blow on the seeds while I turn the bowl and walk around. This is done outdoors, of course. The lighter, empty seeds will blow out of the bowl while the heavy, fertile seeds stay in.

• Put the seeds in plastic, sealable baggies on a humid day, or blow your hot breath into the bag. Insert any labels or tags you want to make before sealing. We use jewelry price tags or small pieces of paper and a Sharpie pen.

• Refrigerate at least four weeks at 41 to 42 degrees. Some seeds will be very dormant. Most will come up without a cool period. Some may sprout in the refrigerator. Most won’t, especially if the parents are types that can go completely dormant in winter. 

The eight-week cooling period is better if dormancy is important to you. It will ensure that all viable dormant seeds come up, along with the ones from evergreen parents that need no cool period. After cooling, plant in a good potting mix in seed flats or pots in spring or in a greenhouse anytime. When the seedlings get planted in the ground, we make labels for them using the tags from the baggies. We print labels using a Brother label printer for outdoor labels. We paste the labels onto pieces of cut plastic slats from discarded blinds. These usually last for the four to six years it takes us to evaluate a daylily seedling. We grow about 80,000 to 120,000 new seedlings a year for evaluation. 

Since we evaluate our seedlings for many years for multiple qualities, we will have more than 250,000 daylilies in bloom in any given year. That represents three to four years worth of seedlings, plus the thousand or so we may have selected to keep as the best from the 80,000 or so we bloomed in a previous year. Eventually, we get the keepers down to fewer than 100 per year, including the 30 or so that we choose to name.

I say this by way of warning. Many of your daylily seedlings will be so beautiful year after next that you will find it hard to part with them.

One of my customers in Greensboro once told me he had torn out his paved driveway to make more room for his daylilies. So you must learn to be very picky about which ones you keep when you start growing daylilies from seeds. Or you will have more daylilies than you can deal with.

Send your questions and comments to Roger at orders@mercergarden.com or call 910-424-4756.  You may message photos and text to that number. Send pest or plant samples to Roger at 6215 Maude St., Fayetteville, N.C. 28306.