SUCCESS WITH SOILS
Probably the most important step to success is soil preparation. Annuals are demanding plants; they require good drainage, even moisture and regular fertilization. To help provide these conditions, start by taking a soil test. Your pH should be at 7 or slightly below. If it is less than 5.5-6, add lime to bring it up. If it is over 7, you can add sulfur.
A good soil lab can provide directions to alleviate the most common soil problems in your part of the country. Beware, though, if they try to sell you specific products. Fertilizers and amendments suggested should be in generic terms. Soil labs should not be in the business of endorsing brand names.
If you're preparing a new bed, it also pays to check the drainage. Most annual color plants will not tolerate soggy soils and succumb to root rots almost overnight. The classic way is to dig a hole about a foot deep and fill it with water. It should drain in less than a day. If it doesn't, you might want to select another site or install a drainage system.
In general, plenty of organic matter helps provide a hospitable rooting environment. Organic amendments are crucial for success in arid environments, where soils have little or no organic matter. The bacteria, organic acids and humus that are associated with organic matter loosen the soil to allow root growth and also help to break down mineral nutrients into a form that is available to plants.
Compost is one of the best amendments; it is generally pH-balanced and loaded with beneficial organisms. One of the benefits of the relatively recent restrictions on yard waste at landfills is that compost facilities are springing up throughout the nation. Just be sure that the material you purchase is thoroughly composted. It should have an "earthy" smell, beware if it smells like ammonia or sulfur. Look for a rich, crumbly texture. Large chunks or slimy materials should be avoided.
Spread three to five inches over the top of your planting bed and dig or till thoroughly into the top 12 inches of the soil. Landscape managers at Sea World in San Diego, CA, add amendments at each color change. At the Tropicana Resort in Las Vegas, where color beds greet the guest at every turn, adding organic matter every time the bed is replanted is also part of the program.
If you have a perennial weed problem, the time to tackle it is before planting. If you can, water the site well to get the weeds up and growing and then zap them with Roundup). If you have annual weeds, be sure that they are removed before planting.
THE RIGHT CHOICE
Now that your site is ready to plant, you need to be careful when you are making your color selections. It's easy to succumb to the charms of a plant that is in full bloom, but generally, these should be avoided. Actually, to get the longest life from your plants, they should just be establishing themselves in the pony packs or pots. A few buds or one open flower is fine, but a plant in full bloom will not last as long as one that has just established itself.
Just a little biology here. Annuals sprout, grow, flower, set seed and die in one year. Their main job is to reproduce quickly. So it only makes sense that a plant in full bloom is entering the last part of its life cycle.
Don't bring problems into your site. Plants with insect infestations or weeds should be rejected without a second thought.
Go ahead and gently remove the plant and look at the roots. They should be plump, white and well established. You want to avoid plants when the roots are a tangled, solid mass. Since annuals grow very quickly, the roots may have started circling in the pot or pack. When planting, you can (gently!) score the roots or slightly spread the root ball by hand so the roots will move into the surrounding soil.
If you plant a lot of color, it pays to establish a good relationship with a quality grower. Investigate your local nurseries. Generally, a capable grower will be proud to show you around. Take a good hard look at the operation. Remember, cleanliness is really next to godliness in a growing operation.
Are the plants lined up neatly? Are there weeds under the benches or in the pathways? (Weeds can easily hitchhike to your site as seeds.) Are tools and materials put away, or are there broken bags of fertilizer and rusty equipment lying around? Are the trucks covered and being loaded with care, or are flats being carelessly flung about? Are the plants perky, or do some show signs of wilting? You might pay a few cents more per flat for quality, but if it lasts a couple months longer, you've more than recouped your investment.
Now it's time to plant. Since we live in an "instant society," we have a tendency to crowd plants together to provide the most bang for the buck up front. If you've chosen young plants, this can be a mistake. If annuals are planted too closely, air circulation will be limited when they reach full size. This is an open invitation to disease. Know how large the plants you pick will grow to be, then space accordingly. There might be too much open area for your liking, but this can be dressed up with a thin layers of shredded bark. As a bonus, the bark acts as a mulch that will hold water and reduce weed growth.
Be sure to water the flats thoroughly before planting, and give them a few hours to drain so you are not handling sopping-wet root balls. Making sure that the root ball is moist at planting time will minimize transplant shock.
Although the use of soil polymers is a somewhat controversial issue, many landscape managers have found that adding a little at planting time helps minimize moisture stress. The Sheraton Hotels in San Diego, California, were built on an artificial "island" and had pure sand as fill. With the addition of soil polymers, irrigation could be cut by 50 percent once the plants were established; from every day to every other day. A teaspoon or less was sprinkled in each planting hole at the time of planting. If you decide to experiment with polymers, DO NOT use more than the recommended rates. After the polymers hydrate, "overdoses" have heaved plants out of the soil!
You can also incorporate a pre-plant fertilizer, using the recommended rates. Slow-release fertilizers can last the entire season, saving labor. In addition, organic fertilizers with humates, bacteria and organic acids can also result in sturdy, steady growth.
Water thoroughly immediately after planting. This helps settle the soil around the roots and also reduces transplant shock. If you haven't incorporated a pre-plant fertilizer, you can use a weak solution of soluble fertilizer right after planting to get the roots off to a good start.
BE A DEADHEAD
Yes, it's too late to quit your job and follow a rock band around the country. But one of the ways to keep your color coming is to deadhead, which simply means removing old flowers. Keeping in mind the annual?s biological cycle, once a plant sets seed it has done its job and can die happily. Thus, if you keep removing spent flowers, the plant will be stimulated to bloom on and on. This can be a tedious job, but if you keep up with it, the payoff is literally months of prolonged bloom. Pluck off spent blooms on a weekly basis and just see the results you get. (You can also select sterile plant varieties that don?t set seed, but that?s another article!)
Be sure to stay on the alert for weeds. If you've prepared your site well and have a layer of mulch, it should be easy to pull any stray invaders when they're still small. Grassy weeds can be controlled with a selective herbicide such as Fusilade.
Unfortunately, the use of preemergence herbicides at the time of planting generally isn't recommended. While the herbicides usually won't kill your new plants, they will inhibit the early root growth that you want to encourage. Once a planting is well established, you can apply preemergence herbicides if it's necessary. (Like all pesticides, be sure to read and follow label recommendations to the letter.)
Proper irrigation also plays a big part in color longevity. The ideal condition is even moisture. Although annuals often pop back quickly after they wilt, this is hard on the plant and will result in shorter life. On the other hand, avoid soggy environments. It's difficult to recommend a set watering schedule because there is so much variability in soil type, climate conditions and even individual plant requirements. Monitor your planting beds carefully, and don't be afraid to experiment with your irrigation cycles.
If you've used a quality pre-plant fertilizer, it should get you through several months or even the plants? entire life cycle. However, many landscape managers like to periodically use a water-soluble fertilizer, especially after major deadheading.
Yes, annuals can be finicky and expensive. But a well grown color bed is a spectacular statement and testimony to your expertise as a landscape professional.