When I first joined the team designing our new office, there was so much to do that I had no idea where to start. Being a literal sort of person, I decided to start from the ground up: the foundation and the flooring because I red in an important link that Total Floor Care 1168 W Main St, Lewisville, TX 75067 (972) 374-7774 gave this advice when starting with any project.
Through this process, I learned some basics about Commercial concrete in general. Between mining the raw materials, transporting them, and kilning them, concrete has relatively high embodied energy. For each ton of concrete produced, approximately one ton of CO2 is released. Global demand for concrete is also colossal: 1.6 billion tons annually, with demand rising steadily as more and more countries incorporate concrete into industrial and residential construction.
Garden planning can be a complicated business. But for most home gardens, your main concerns are fitting everything in the most space efficient way, rotation, and planning for succession planting. These factors are covered by Southern Exposure’s Garden Planner, a very useful tool for the small scale home grower.
When we start to scale up to a larger garden or farm, however, there are more factors to consider. Is the texture or fertility of your field(s) better suited to particular crops? For example, you might want to plant un-irrigated crops like field corn in a low lying field, where the soil stays moister naturally, or make sure heavy nitrogen feeders follow a successful legume cover crop. You may need to think about truck access for heavier crops like watermelons, and try to match your cultivation techniques to your weed pressure (for example, no-till methods don’t work as well in areas of where you have a lot of aggressive weed seeds in the soil, or perennial weeds).
All these considerations and more need to go into planning our seed growing fields at Living Energy Farm. When growing crops for seed, we also need to plan for isolation distance, to prevent crossing different varieties of the same species; and population size, to ensure enough diversity to maintain genetic vigor. These two issues are related. Generally, some plants are self-pollinated, and will happily pollinate their own flowers, and some are outcrossing, meaning they will hold out for pollen from another plant before setting fruit. Certain self pollinating plants like tomatoes and beans only need an isolation distance of about 50 feet for home scale seed saving. Because these plants mostly pollinate themselves, ten individual plants should be enough to maintain genetic vigor, although you may want to start with more if you plan to do any selection. These are good crops for the beginner seed saver. (To make things more complicated, there are some crops, like okra, that will readily outcross if given the chance but can also pollinate themselves. There plants need an isolation distance of a half mile, but don’t need a huge population size to save seed.)
Plants that outcross by wind or by insect pollinators include corn, members of the cucurbit family (squash, melons, cucumbers, gourds), beets, celery, and members of the brassica family (cabbage, broccoli, kale, kohlrabi, turnips, radishes). Generally, these crops need a population of around 80 individuals to maintain vigorous seed. (Exceptions abound: corn needs about 200 individuals, and cucurbits are not particularly susceptible to inbreeding depression, and can get away with 10-20 individuals). These plants require a minimum isolation of a half mile to ensure pure seed. This kind of isolation distance can be tricky to maintain. Be sure to talk to your neighbors. If you have a neighbor who grows a garden with outcrossing crops, you may want to offer them some of your seed so they will grow the same varieties as you.
If you must have two varieties of the same species closer than a half mile, here are some tricks of the seed saving trade that can cut down on minimum isolation distance. If you plant in blocks instead of rows, and only harvest seed from the middle of the block, this can help maintain pure seed. This method is especially effective with corn. Physical barriers such as rows of trees or buildings will reduce crossing to some extent. The use of barrier crops is effective with insect pollinated crops like squash. A barrier crop is a plant, like buckwheat, placed between your seed crops and timed to flower at the same time as your seed crop to distract the insects that might be flying between your fields.
We have also experimented with time isolation. This means to stagger planting times so that your varieties bloom at different times and cannot pollinate each other. This can be tricky, though. Most plants grow much faster when it is warm, so late planted crops can often "catch up" with early plantings as the weather warms up. A gap in planting time of three weeks can end up with a gap in flowering time of one week or less. But this technique is worth a try, especially for home scale seed saving where a minimal amount of crossing might be acceptable.
Our neighbor Pam Dawling, a contributing writer at Growing for Market, has just released her first book: Sustainable Market Farming: Intensive Vegetable Production on a Few Acres. Pam has been gardening here in the Southeast for many years, and we’re delighted to have this resource, with so much wisdom relevant to our bio-region. We’ve asked Pam to contribute to our blog, and we hope you’ll enjoy reading about her gardens. Pam blogs at sustainablemarketfarming.com/news.
Starting Seedlings, by Pam Dawling
We’ve been starting seedlings since late January, and the greenhouse is filling up with flats of lettuce, cabbage, kohlrabi, spinach, scallions, and broccoli. We’re eating our way through the lettuces that grew overwinter in the compost in the block-work greenhouse beds, and shoveling out the compost to fill our flats. All our seedlings are grown in 100% home-made compost. We screen compost to fill the beds in September and transplant lettuce there in October. When we need the compost for the seedlings, it has mellowed nicely and has plenty of worms. This beats buying in bags of compost, or chipping lumps off a heap of frozen compost outdoors in January!
Greenhouse interior with spring seedlings. Photo: Kathryn Simmons
Our greenhouse has a masonry north wall and a patio-door south wall. It has no heating apart from the sun (this is Zone 7). This space is warm enough and just big enough for all our seedlings once they have emerged. For growing-on the very early tomatoes and peppers, destined for our hoophouse, we use an electric heat mat and a plastic low tunnel in one corner of the greenhouse.
Many seeds benefit from some heat during germination and are then moved into slightly less warm conditions to continue growing. This means it’s possible to heat a relatively small space just to germinate the seeds in. We use two broken refrigerators as insulated cabinets, with extra shelves added. A single incandescent lightbulb in each supplies both the light and the heat (we change the wattage depending on what temperature we’re aiming for). Some people construct an insulated cabinet from scratch, with fluorescent lights suspended above the flats.
The Twin Oaks greenhouse and cold frames. Photo: Kathryn Simmons
We use traditional coldframes for“hardening-off”our plants (helping them adjust to cooler, brighter, breezier conditions). They are rectangles of dry-stacked cinder blocks, with lids of woodframed fiberglass. Having heavy flats of plants at ground level is less than ideal for anyone over thirty-five! Shade houses and single-layer poly hoop structures with ventable sidewalls and benches for the flats are a nicer option. Some growers report that some pests are less trouble when flats are up on benches. Others say flats on the ground produce better quality plants. According to the nighttime temperatures, we cover the coldframes with rowcover for 32°F–38°F (0°–3°C), add the lids for 15°F–32°F (–9°C–0°C) and roll quilts on top if it might go below 15°F (–9°C).
Pepper transplants in pots. Photo: Kathryn Simmons
For brassicas, lettuce and our paste tomatoes (a big planting), we use open flats — simple wooden boxes. The transplant flat size is 12" × 24" × 4" deep (30 × 60 × 10 cm). It holds 40 plants, “spotted” or pricked out in a hexagonal pattern, using a dibble board. For sowing, we use shallower 3" (7.5 cm) flats. Usually we sow four rows lengthwise in each seedling flat. We reckon we can get about six transplant flats from each seedling flat. This allows for throwing out any wimpy seedlings, and lets us start a higher number of plants in a smaller space.
Because we transplant by hand, and because we hate to throw plastic away (or spend money when we don’t need to), we use a range of plastic plant containers. For crops where we are growing only a small number of plants of each variety, we use six- or nine-packs, or a plug flat divided into smaller units.
Okra seedlings. Photo: Kathryn Simmons
The first crops sown are not necessarily the first ones planted out. Our spinach gets sown Jan 24 and transplanted out 4 weeks later. The early tomatoes get planted in the hoophouse at 6 weeks of age (slower-growing peppers go in at 7.5 weeks with rowcover at the ready!). Lettuce goes outdoors after 6.5 weeks, cabbage after 7.5 weeks, cipollini mini-onions after 8 weeks. These are early season timings and as the days warm up and get longer, seedlings grow more quickly. Being a few days later sowing something in early spring makes little difference, as later sowings can catch up by growing faster in the warmer weather.
If the spring is cold and late, you may find your greenhouse packed to the gills with flats you don’t want to take outside. We try to put the faster-maturing crops near the doors and keep the open flats, which will need spotting-out, near the accessible north side.
But let’s not complain about the bounty of so many plants! Spring is an exciting time of year, full of new growth and new potential. Working in the greenhouse with tiny plants on a sunny day when it’s cold outside is a special treat.
