Gardening in Tucson
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Dealing with Critters
Digging Holes for Plants
Fruit: Selection, Cultivation
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Gardening Schedule Tucson
Oracle: Weather, Wildflowers
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Selecting Plants: SE Arizona
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Although native plants have evolved to survive in our demanding climate, scattering seed in your yard and expecting nature to take over does not assure success. Nature scatters thousands of seeds for each that grows. Much is eaten by animals, dries up from lack of water, or is carried by the wind to germinate elsewhere.
If you want your native seeds to grow at your place, you must cover them, water, weed and help them along for a season or two. Once established, native plants require little or no effort. But do the work to get them established.
Seed Germination Techniques
Many native wildflower seeds collected in the wild need encouragement to sprout. Search the Internet for germination techniques specific to the species you wish to grow. Below are some general rules, which also work with commercial vegetable seeds.
Moist cold stratification is for seeds from cold winter climates.
Scarification is the removal of part of a seed coat to allow easier water penetration. It is done when a seed coat is hard or thick. Rub the seed coat gently with a file, sandpaper or knife sharpening stone to remove some of the coat without damaging the seed underneath. For seeds with a flat shape, like squash seeds, nick the edge of the seed in several places. This will allow water to seep in quickly and trigger earlier sprouting.
Soaking is suggested for some seeds, especially those with thick or hard coats. To be on the safe side, do not use water more than 90°F. and let cool while soaking. The number of hours to soak depends on the species, and scarification first may help speed the process. Plant the seed immediately after soaking.
Native plants expect native soil. Do not amend the soil unless you are sowing seeds of plants needing another soil type. But first, unless you are planting vegetables or fruit trees, ask yourself why you are planting anything not suited to the local environment that will necessitate more work, when there are native plants that will do just as well.
Start with a weed free area. Only double-dig if your soil is hard packed like a parking lot. Avoid rototillers because they create a hard layer of compressed dirt just below the reach of the rototiller blades.
When double-digging to start a new garden bed, wait before sowing seed. Water and allow the first flush of weeds to appear. Remove those weeds, water and weed again. Now plant the seed.
In a small area, hoe or hand weed to remove existing vegetation. Be sure to remove any and all roots of unwanted weeds.
When to Plant
See directions on the seed packet, or for wild seeds, look for Internet advice. For seeds needing little or shallow cover, sow them among closely packed gravel one layer deep to prevent animals from finding and eating the seeds.
Seeds from cold winter areas may need to be sown in the fall and overwinter outside. Do not water these seeds and do not expect germination until the following spring.
Seeds from warm areas should be sown in spring after the danger of frost has past. Water these seeds immediately after planting. The 25-day weather forecast (accuweather.com, etc.) can be used to determine if the last frost has ended early. In warm winter areas, sow annuals anytime and water to help germination.
Warm season grasses germinate when the soil is warm. That is the time to plant. To plant when the soil is cold, cover carefully and water when the soil warms up. Cool season grasses, which need spring rain and disdain our dry soil, are not recommended for Arizona.
Nature plants seeds at all times. One of the great times is the rainy season. Wait, then plant.
Do not sow too much seed in too small an area. Hand broadcast the seed over the area to be seeded. Since it is hard to distribute a small amount of seed evenly over a large area, you may wish to mix seed with sand or organic material to increase the volume you are spreading. For best coverage, go over the area twice, north to south, then east to west.
Rake to cover the seed with soil to a depth of 1/4 to 1/2 inch. Desert plant seeds are best sown among gravel closely packed in a shallow layer. Pea-sized pebbles and crushed granite can be used. Covering the seed is critical so that it does not blow away, get eaten or dry out.
An alternative to sowing in soil, for seedlings that can be transplanted, is to sow in pea-sized gravel 4" deep. The gravel should be mixed with fine soil first. Sow the seeds into the gravel and water gently. The gravel will serve as a mulch, protecting the seeds from birds, wind and sun. Moisten the gravel daily. When the seedlings are large enough to transplant, carefully remove their roots from the gravel.
Do not sow your seed unless you are ready to mulch. Many seeds are lightweights and have built in feathers specially made to waft them into another yard.
Mulch helps keep your soil moist and can add nutrients. Soil is a good mulch for seeds, but for desert plant seed, small gravel, sand, or crushed granite also works well.
Binder, finely ground plant material that gets sticky when moistened, will help keep your seed, soil and mulch in place, especially on steep slopes and in windy areas. Sprinkle the binder at a rate of 1-2 pounds per 1,000 square feet over the soil and the mulch. On steep slopes, more binder may be helpful. Wet the area after putting on binder so it can do its job of holding everything to the soil. Binder is effective for about a year, by then the sun and soil creatures have decomposed it.
Keep the seedbed damp. Water maybe 2 times a day for the first 3 weeks, barring rain. This is not deep, expensive watering. It is lots of shallow waterings. If the seedlings dry out, they die. Water maybe once a day for the next 3 weeks.
When seedlings are one inch up their roots can be 3 inches down. Clearly now you can water less frequently and more deeply. After the initial 6 weeks, water deeply perhaps 2 times a week for a month, then once a week for another month, then twice monthly until frost. Make appropriate modifications for the weather and other conditions.
After plants are established, only occasional waterings, perhaps one a month, are needed during dry spells.
When weeds appear, pull them out before they get too big. Otherwise a seemingly small problem will take over your native planting. With hard work, we are attempting to jump over years of successional weed growth to a more stable climax grassland or meadow in a season or two.
Once established, your lawn or meadow should require only minimal hand weeding.
Mowing stimulates tillering (vegetative growth) of grasses and helps control weeds by removing their seedheads before the seeds mature.
Short mowing can increase water needs. Do not cut newly sown grasses (especially bunch grasses) shorter than 4 inches high.
Wait to mow a wildflower meadow until after the flowers have all bloomed and set seed.
Phemeranthus aurantiacus: Orange Flameflower