Tuesday, February 24, 2009

Fertilizing for Spring Green

By Pam Brown, Urban Horticulture Extension Agent

When you start seeing new green leaves on landscape plants or your grass is beginning to grow, it is time for spring fertilizing. At the most basic level, fertilizers provide nutrients that help plants grow better. You can fertilize by applying compost, a packaged commercial fertilizer or a specific mineral, such as iron. Lawns, woody landscape plants and palms benefit from different fertilizer blends, so I encourage you to review the linked University of Florida/IFAS publications listed below for specifics.

When selecting fertilizer, you will see three numbers listed on the bag like 15-0-15 or 16-2-8. The first number is the percent of Nitrogen contained in the bag, the second number is the percent Phosphorus and the third is Potassium. You will want to look for slow-release fertilizers or at least fertilizers with a high percentage of slow-release nitrogen in them. Nitrogen promotes shoot growth, so if you use slow-release nitrogen, you will have less of a succulent new growth surge. Using slow-release fertilizers can lead to less insect problems for both lawns and landscape plants since insects are attracted to the tender new growth. Slow-release products are also less likely than 100% water soluble fertilizers to leach through the soil to ground water in heavy rain events. When looking for slow-release, other words can mean this same thing, like poly coated, sulfur coated, or water-insoluble.

Be careful when applying fertilizers, they can be a real source of pollution in our waterways, bay and gulf. It is best not to apply fertilizer if heavy rain is forecast. Using a drop spreader will help keep fertilizer away from water bodies, driveways and sidewalks. If you spill fertilizer granules, sweep them up or back up onto the lawn. Rinsing them off hard surfaces with a hose could send fertilizer down the storm drain. In the summer you can apply chelated iron or iron sulfate instead of nitrogen to green up the lawn without increasing growth. Also use caution applying “weed and feed” products. The herbicides in these products can injure some trees and shrubs.

Fertilization of Turfgrasses on Florida Soils
Fertilizer Recommendations for Landscape Plants
Fertilizing Landscape Palms in Florida Landscapes
How to Calibrate Your Fertilizer Spreader

Friday, February 13, 2009

Try Growing Herbs

By Pam Brown, Urban Horticulture Extension Agent, Pinellas County Extension

There are many different herbs that can be grown in our gardens. Herbs for cooking come to mind and are probably the most useful to the home gardener.

Most culinary herbs can be grown in Florida. Herbs with gray-green leaves like lavender, wormwood, and lambs ears do best in our cooler months as they tend to get moldy during our humid summer. Rosemary, parsley, dill and chives are very popular and are easy to grow. Rosemary will grow into quite a large bush. Basil is an annual, so to keep a good supply, plant seeds every few weeks to keep vigorous plants all summer and through fall. Parsley and dill will attract swallow-tail butterfly caterpillars, so plant enough to share.

To successfully grow herbs, choose an area with 4 – 6 hours of sun and well-drained soil. Herbs do not like wet feet so in our rainy summers it is a challenge to keep them happy. Adding compost can help with drainage, will add slow release nutrients, and help keep down fungal diseases. Herbs do not like much fertilizer ‑ that is why compost is a good source of nutrients. Too much fertilizer will cause fast growth at the expense of developing the oils that are the source of the flavors or scents. If you plant mint, be aware that it can grow rampantly so you might want to keep it in a pot where no roots can get into the garden soil. It can become very aggressive to the point of crowding out other desirable plants.

Speaking of pots, use pots with good drainage. The soil you use should be loose and well drained. You can make a good mix for container grown herbs by mixing equal parts of potting soil, peat moss, and perlite (or vermiculite). Watering is the most difficult part of container gardening. Plants growing in containers dry out faster than those in the ground, so you will need to check the pots every day when the weather is warm and dry.

For additional information, check out our short video below and for further reading access the UF/IFAS Extension publication Herbs in the Florida Garden at; http://edis.ifas.ufl.edu/document_vh020

Tuesday, February 3, 2009

Early Spring Rose Care

By Pam Brown, Horticulture Extension Agent

If you have roses in your landscape, the spring chores of pruning, fertilizing and mulching need to be started now.

What do we do first?
Pruning is first ‑ choose three to four healthy large canes, then completely prune out all of the small canes. Also remove those that grow in toward the center of the plant or are rubbing other canes. Choose an outward facing bud and prune at a 45 degree angle about 1/4 inch above the bud. Prune to healthy wood ‑ green bark on the cane and white pith core revealed with the pruning cut. If the pith is brownish ‑ prune further down or remove the cane all together. The American Rose Society recommends covering the cut surfaces where you prune with white glue to discourage boring insects. Clean up all leaves, canes and other debris around the roses. This helps remove the fungal spores that have over wintered and cause the dreaded black spot disease on the leaves.

What types of fertilizers are best for our roses?
A commercial fertilizer with a ratio of 3 N ‑ 1 P ‑ 2 K that also includes Magnesium and has at least 50% of the Nitrogen as a slow release form is a good choice. Some rose references recommend adding bone meal or superphosphate to the soil at planting and then in the spring, but we already have sufficient phosphorus in the soil and adding this might lead to toxicity for the plant. You can find special rose fertilizer, but be cautious if the second number is very high. We do need to fertilize about 6 times in our area during the growing season. ½ cup of Epsom salts per plant will add needed Magnesium if the fertilizer does not contain it.

Is mulching a good idea around roses?
Yes ‑ organic mulch always helps to reduce the loss of soil moisture, keeps down weeds that compete for nutrients and helps keep the temperature of the soil constant. Remember to keep the mulch a few inches away from the base of the rose plant. Piling mulch up against the base can encourage fungal diseases.

And that awful disease black spot ‑ what should we do for this?
Many of the hybrid roses are very susceptible to the fungal disease black spot. First a yellow spot forms then the center turns black and eventually the whole leaf dies and falls to the ground. Keep the area around the roses clean and start a spraying schedule early. There are fungicides for this problem and a home remedy called the Cornell Fungicide formula that works fairly well if started early. The best thing to do is to plant roses that are disease resistant such as “old garden roses” and shrub roses such as the “Knock-out” series. Then you can just stand back and admire them.

Please also view our short video on growing roses.

Additional information is avialable on the Internet from the University of Florida/IFAS Extension:

Growing Roses in Florida

Pests of Roses in Florida