Healthy soil and sustainable growing

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Succession Planting (or "Don't Stop Now") - Part 2
(see eNewsletter #21 for part 1)
by Steve Peters
http://www.seedsofchange.com/enewsletter/issue_68/successionplanting.asp

Memorial Day weekend has come and gone, and homeowners throughout North 
America have followed a time-honored tradition. Over these hallowed three 
days, gardens are duly planted, and then often ignored (except for weeding, 
of course!) until early August, when the harvest season commences. In fact, 
as we gardeners know, the gardening season never stops, and we all have 
favorite strategies to get our plants in early to maximize the season. But 
let's not forget that there are many opportunities later in the summer to 
continue planting all kinds of crops and reaping those harvests for many 
months to come.

It is true that summer annuals (crops sensitive to frost) requiring 100 or 
more days to maturity have a limited planting window that ends, for the most 
part, by mid- to late June—summer solstice time, if your first fall frost 
date is some time in October. This would include all tomatoes, peppers, and 
eggplant (all from transplants), melons, and most corn, bean, squash and 
pumpkin varieties. Almost all other vegetables, however, have extended 
planting seasons that, in some crops, can last all summer long. For 
successful production, the most important factors to remember are: 1) your 
first average fall frost date, 2) days to maturity (from direct seeding or 
transplanting) of the specific variety you are sowing, and 3) whether the 
plant is frost-tender or frost-tolerant.  In addition, as the summer 
progresses toward mid- or late August, the day length begins to shorten 
noticeably, and the number of useful daylight hours for ripening a plant also 
lessens. For example, lettuce planted in mid-May may require 55 days to form 
a full head, but that same lettuce variety planted in mid-August may require 
70 days to form a full head, because there are many less hours of effective 
sunlight in September and October compared to June and July.

The following is an approximate guide for planting opportunities after the 
summer solstice (June 21) for our common garden vegetables, if the average 
first frost date is mid-October. Adjust accordingly for earlier or later 
first frost dates in your area.
Last Planting: Early to Mid-July

    * Bush Beans - many varieties are ready in 50–60 days and can be planted 
until mid-July; late plantings avoid the ravages of the Mexican Bean Beetle
    * Broccoli - direct seed into a well-prepared nursery bed, and then 
transplant throughout the garden when seedlings are 4–6 weeks old
    * Cabbage - same as broccoli; however, varieties over 90 days to maturity 
may not reach full maturity if planted in July
    * Chinese Cabbage - same as broccoli
    * Cauliflower - same as broccoli
    * Corn - plant only varieties such as Hookers or Triple Play that mature 
in 60–70 days.
    * Cucumber - the longest maturing varieties require 75 days
    * Chicory - leaves can be harvested in 60–70 days, or roots can be 
harvested in 100 or more days
    * Okra - loves the heat, and matures quickly
    * Leeks - from transplants
    * Radicchio - same as chicory
    * Rutabaga - a cold-hardy root that requires a fairly long, cool season 
for best results
    * Summer Squash - great for quickly filling in empty spots in a 
mid-summer garden

Last Planting: Late July–Early August

    * Carrot - varieties requiring 80–100 days to reach full maturity, eg. 
Kurota Chantenay, Japanese Imperial Long, Scarlet Keeper, and St. Valery, may 
not reach full size if planted at this time
    * Chard - can be planted even later but yields will decline
    * Collard - same as broccoli above
    * Kale - same as broccoli
    * Pea - a narrow planting window of opportunity for producing a fall crop

Last Planting: Mid–Late August

    * Beet - if grown with protection such as a cloche or hoop house, can be 
planted well into the fall season
    * Beetberry - vigorous cool-season re-seeder produces tasty spinach-like 
leaves and mildly sweet berries
    * Broccoli Raab - same as broccoli above
    * Endive - wait until the end of August as soil temperatures begin 
cooling, and keep soil moist for best germination results
    * Lettuce - plant every three weeks throughout the summer for continual 
harvests; can be planted in September but yields decline significantly
    * Mustard - sow in nursery bed and then transplant throughout the garden
    * Orach - germinates in warm soils but thrives in cool weather
    * Purslane - can be planted all summer when soil temperatures are warm
    * Spinach - planting at this time produces tasty greens in October
    * Turnip - fall roots are extra sweet

Last Planting: Early–Mid September

    * Arugula - versatile, quick green that will re-seed and emerge early the 
following spring
    * Cress - rapid-growing green that can be planted throughout the winter 
if grown under cloches or a hoop house
    * Huazontle - tasty, vigorous green related to lambsquarter (Chenopod 
family) that also produces nutritious seeds if planted earlier
    * Komatsuna - quick-maturing Asian green that can be planted in nursery 
bed and transplanted like other brassicas (broccoli, kale, etc.)
    * Onion - in climates with minimum winter temperatures above 10º F (Zone 
8 and warmer), short–mid day length-adapted varieties such as Riverside and 
Valencia can be planted throughout the southern U.S; long day length-adapted 
varieties such as Siskiyou Sweet can be planted in western Oregon and 
Washington
    * Radish - quick-growing roots have milder flavor in cool soils
    * Spinach - planting at this time produces small plants in the fall that 
go dormant during the winter and resume growing in early spring; harvest 
begins in late March, assuring continual production throughout the spring

Most of the common summer annual flowers that require warm soil temperatures 
for germination can still be planted until the end of June. When planted 
late, however, the bloom season is limited to the last few weeks before the 
fall frosts. These species would include Amaranth, Celosia, Coreopsis, 
Cosmos, Daisies, Marigolds, Morning Glories, Strawflowers, Sunflowers, and 
Zinnias.

In a climate where the minimum winter temperatures are above 0º F (Zone 7 or 
warmer), many annual flowers that are particularly cold-hardy may be planted 
during the last month of summer (August 20–September 20). Some species, 
notably Larkspur, Bachelor Buttons, and Nigella, will even overwinter in Zone 
5. These plants will begin growing during the fall, stop growing during the 
winter, and resume growth the following spring as soil temperatures rise. It 
is recommended to cover the young plants with straw or leaf mulch during the 
winter, although this may be unnecessary if winter conditions are mild.

The most reliable and well-known flower species that can be planted during 
late summer for early blooms during the subsequent spring include Bachelor 
Buttons, Calendula, Flax, Larkspur, Nigella, Snapdragon (actually a biennial 
or short-term perennial in very mild-winter regions), and Sweet Pea. Other 
species that may over-winter successfully if conditions are favorable, 
although not as reliably as the previously-listed species include Alyssum, 
Agrostemma, Borage, Cleome, Lavatera, and Scabiosa.

There are also a few annual or biennial herbs that are quite winter-hardy and 
can be late-summer planted and will survive the winter in regions in Zone 7 
or warmer. These herbs include Cilantro, Dill, Fennel, and Parsley. It is 
worth trying these in colder climates too, especially if you have protected 
microclimates in your garden. A south-facing wall or even a boulder to hold 
the sun's warmth can make a difference.

Another opportunity for summer planting involves most of the perennial 
flowers. These plants are typically started in greenhouses during the winter. 
Those of us without a greenhouse, however, can prepare a nursery bed in our 
garden specifically for direct seeding of perennials during the summer. It is 
important to keep the bed free of weeds, as most perennials are very slow 
growing and are not competitive with fast-growing annual weeds. Be sure that 
your nursery bed has adequate irrigation and has at least average fertility. 
Plant your perennial seed at least ten weeks before the first fall frost to 
allow for the plants to become established before the onset of winter. The 
following summer, when the plants are one year old, it will be time to move 
these plants from the nursery bed to their permanent location in the garden. 
The most common perennial flower species that would be suitable for this type 
of propagation would include Anthemis, Bergamot, Campanula, Columbine, Shasta 
Daisy, Delphinium, Echinacea (requires 60–90 day cold stratification for 
germination), Foxglove, Gaillardia, Hollyhock (actually a biennial), Lobelia, 
Penstemon, Pinks (Dianthus), Evening Primrose, Rudbeckia, Salvia (many 
species), Snapdragon, and Yarrow (Achillea).

Planting seeds throughout the summer means that we can enjoy a bountiful 
harvest for a much longer time, but it also is significant in other ways. As 
gardeners, we are often limited for space, so it is important to maximize 
every square foot of available soil area. In essence we are trying to capture 
the greatest amount of solar energy possible in the space available to us. 
The best way to do this is to have 100% coverage of your garden's surface 
area at all times. From the information above, it should be clear that there 
are many plants that continue to grow and thrive throughout the summer and 
fall and early spring seasons. By growing different species together, no soil 
surface is left bare. This maximizes soil cover, intensifies soil biological 
activity and above-ground insect activity, and increases overall plant 
yields. Of course, it is essential to maintain fertility in such an intensive 
system, so keep that compost pile going!

The following are examples of crops growing together simultaneously for at 
least part of their life cycle:

    * Sowing buckwheat between tomato plants keeps weeds suppressed, adds 
carbon to the soil, and improves soil structure. The buckwheat can be mowed 
with a Kama (hand sickle) before it competes with the tomatoes and left as 
mulch. This technique also works well with squashes and cucumbers, which have 
lots of bare soil around them as they develop. If you use floating row cover 
to control pests, the buckwheat can actually lift the row cover off the 
plants. Remove the row cover when the squash flowers and again, cut the 
buckwheat and leave as a mulch.
    * Transplanting lettuce into a stand of broccoli (or other brassicas such 
as kale or cauliflower) maximizes available garden space of two species that 
have different plant architectures but similar growing requirements. The 
lettuce is harvested as the brassica plants fill in, having acted as a living 
mulch to suppress weeds and hold soil moisture. The brassica plants also 
provide a little protection for the lettuce as it develops.
    * Planting radishes and carrots together allows for an early harvest of 
radishes followed by a later carrot harvest. The radishes also help to mark 
the slower germinating carrot rows so an early cultivation can be done before 
the carrots emerge.

There are many more examples of inter-planting for maximum production. 
Quick-growing plants such as radish, arugula, or cress can be sown into 
already-established beds of tomato, pepper, corn, or beans. Plants that are 
easily transplanted such as brassicas, greens, or basil can be planted into 
open spots throughout the garden to insure that no space is wasted. The 
primary limitation is the availability of water. If water is available, the 
only limitation is your own imagination!
The tradition of planting everything on Memorial Day and then calling the 
garden planted is really a myth. The far more ancient traditions of gardening 
cultures, such as China's, follow a sequential planting much like that 
outlined above. Many Asian vegetables, for example, are bred to mature very 
quickly, and often do better when planted later in the season. In a society 
where arable land is scarce, gardening all year round is more than just an 
efficient system. It means that the people have enough to eat. So keep on 
sowing for a bountiful, beautiful garden, and an extended harvest of the 
finest food available, organically grown in your own backyard.

Steve Peters
Seeds of Change Product Development Manager

Photo Captions:(1) Lettuce utilizes the space between young broccoli 
transplants while providing a living mulch. As the broccoli grows. it 
provides shade for the lettuce, helping prevent bolting. (2) Buckwheat 
controls weeds and protects soil between tomato transplants (left) It took 
ten minutes to mow the buckwheat with a Kama and remove the suckers on all 
the tomato plants. (3) Heads of Reine de Glaces lettuce intercropped with 
onions to utilize space, protect the soil and control weeds. Onions will be 
sidedressed with compost as lettuce is harvested.