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From The Professor's Greenhouse: Biennials (Part 1)

Season-relevant tips on planting, growing, and maintaining thriving gardens and landscapes from

Professor Kevin Jones, Botanist & Biology Professor at Charleston Southern University.

To plant a garden is to believe in tomorrow.

-Audrey Hepburn

Biennials grown as food crops include the ‘cole crops,’ lettuce, turnips, carrots, beets,

and many more.

One of the talents gardeners possess is foresight. Another is patience. To have a head

of cabbage in your garden, there were seeds planted four to six months before and

patient nurturing with water, fertilizer, and protection from pests. Planting biennials in

August and September brings the promise of vegetables in winter and spring and

flowers in spring and summer.


Biennials are plants with a life cycle between that of annuals and perennials. Annuals

are plants that go from seed to seed in one growing season, whereas perennials return

year after year. Biennials, though, have a two-year life cycle. In the first year or

growing season, they grow vegetatively and store nutrients for the second season,

when they often rapidly transition into a flowering, seed-producing plant and then die,

leaving the seeds to repeat the process. By planting many biennials in late summer and

fall, the chill of winter triggers the change.

Biennials grown as food crops include the ‘cole crops,’ lettuce, turnips, carrots, beets,

and many more. Here in zone 8b, they are planted in the fall for the first part of their

growth cycle, and by the spring, they have stored the energy needed for flowering. We

can take advantage of this by harvesting them before they ‘bolt’ or change from leafy

growth to flowering.

Miss Karen gets transplants of many of these in the fall for planting in September, but

seeds of some of these can be started now in containers for transplanting later. Or,

seeds can be planted in the shade of vegetables already in the garden, and with some

care in removing the shading plants (just cut them at ground level), the new plants will

have a head start on fall.

A guide to a fall planting of some biennials that do well here in zone 8b:

Beets – plant from early August into September. Beet seeds are sometimes slow

to germinate, but soaking overnight will speed this up.

Broccoli, Brussel Sprouts, Cabbage – Best planted from transplants after mid-

August into late September.

Carrots, pictured below – sow from seed any time in August and into September.

Collards and kale, mustard – sow seed in early to mid-August, Plant transplants

late August into late September.

Lettuce – Lettuce seeds do not germinate well in warm soil. Placing the seeds

on a damp paper towel in a plastic bag and putting it in the refrigerator for

5-7 days will germinate the seeds, and they can then be set in moist soil from mid-August to late September. Lettuce transplants can be planted

after mid-August.

Turnips – can be sown from early August into early October. They can be sown

close together for greens (yum!) or 5-6 inches apart for roots to mature.

Veggie August chores( Stay Tuned For Ornamentals To Do List in Part II Next Week )

1. Irish potatoes can be planted from late July into late August. The new potato

develops above the level of the planted piece, so there are two tricks to take

advantage of this.

0ne, set the potato in the bottom of a furrow and mound the

soil around the developing plant as it gets taller. A second method is to plant the

potato about an inch deep, and as the potato plant grows, add layers of mulch,

and the developing potatoes will form in this mulch layer. This last method is

suitable if the soil is dense or has poor drainage. It also makes harvesting much


2. English peas may be tricky as warm soil is not their friend, but sowing now will

give a harvest before the first frosts cause the blossoms to fail. Sow an early

maturing variety thickly in late August into September.

3. Weeds are plants too. They are likely setting seeds now, also. Every weed

allowed to set seeds this year is a family of little weeds next year. Get rid of them

before they set or scatter seeds to save bother next year.

4. Harvest vegetables frequently and regularly to extend production and to enjoy

the best fruits. The okra picked today would be too woody to eat in two days.

5. Remove plants that are no longer producing. They will only take up space and

likely harbor pests.

6. As crops are removed from areas that will not be planted again until spring,

consider a cover crop such as field peas. Being a legume, they will add nitrogen

to the soil as well as keep weeds and erosion at bay.

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