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
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
easier.
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.
