Mulches To help control weeks and temperature, most of our crops are planted on beds mulched with plastic. These are actually made of polyethylene materials, specially manufactured to stand up to the sun. The mulch comes on a large (heavy!) roll which may hold 2000-4500' of mulch. A mulch layer machine unrolls the mulch onto the bed and buries the edges of it. The ends must be cut and buried manually with shovels.
Mulches are available in different colors. We generally use white mulches to reflect the heat since most of the year we want to keep the root systems cooler. However, sometimes during the winter we use black mulches on crops such as corn which prefer warmer temperatures.
We also use reflective mulches which look like aluminum foil - mainly for tomatoes and squashes. Since many flying insects use the sun as their navigation system, these mulches reflect the sun. The insects think that the mulch is the sun , so they fly away from it. This keeps them from landing on our young plants. These mulches are especially important for early season protection of our crops from insects which vector virus diseases to the plants.
Organic mulches, such as composts and bark, are sometimes used. They are generally a better choice environmentally, but not nearly as effective in controlling weeds as the plastic mulches.
Ditch (on right) for subsurface irrigation
Irrigation We are fortunate to have two types of irrigation systems on our farm. One is used by most farms in southeast Florida. It's called subsurface seepage irrigation, and it means we maintain a perched water table about 18-24" deep. Roots of our crops are able to access the moisture in that water table.
We also use a drip irrigation system. Our irrigation schedules are based on the University of Florida (UF) recommendations. These schedules are based on the amount of water put out by our drip tape, the day length and the average evaporation rate in our area during each month. In our sandy soil, it usually means watering at least once a day for one to three hours. The other advantage to drip irrigation is that we can easily add plant nutrients or other chemicals directly to the root area of the crops.
In the first few days after crops are seeded or transplanted, it is sometimes necessary to use an additional method of watering to get the water directly to the root area, until the roots spread out. To accomplish this task, a “water wagon” is pulled behind a tractor or the very large field sprinkler.
Fertilization By using compost, we add some nutrients as well as microorganisms to the soil. (The soil microorganisms change some nutrients into forms that plants can use.) However, in this climate and soil, we get the best yields by starting with a little potassium and nitrogen put into the field before the beds and made, and then additional amounts are added through our drip system, usually twice a week. The amounts we use are based on UF research. The only other nutrients we add as fertilizers are a high phosphorus “starter solution”, which we sometimes use to water the transplants and seedlings soon after planting, and sometimes some foliar micronutrients when indicated by plant symptoms or tissue tests. The most common of those are calcium, magnesium, boron, iron, or manganese. Other than the small amount in the starter fertilizer and the phosphorus which is present in our compost, we have not added any fertilizer to these fields in 17 years.
Pounding tomato stakes
Staking Most commercially produced fresh market tomatoes are determinate, which means they grow to about 30-36" high. These were developed because they are much easier and cheaper to grow, since they only require about a 4' stake. However, most of the old-fashioned “heirloom” tomato varieties and some modern home-garden and cherry tomatoes, are indeterminate and require 6' stakes. (Some plant physiologists and tomato breeders say that it’s not a coincidence that the tomatoes from these old indeterminate varieties usually taste better. It’s easier to produce a good tasting indeterminate tomato, because there are more leaves to produce the sugars and other chemicals which contribute to tomato flavor.) Our crew pounds in all the tomato stakes by hand. Then, as the plants grow, they are tied with twine by looping it around each stake between plants. There are usually four levels of ties on the determinate tomatoes and eggplants, and six on the indeterminate ones.
Row covers for cold protection
Cold Protection In those rare times when a possible frost is predicted, we sometimes use row covers to protect crops. These fabrics are made especially for covering crops. They come in large rolls and can give 2-6 degrees of cold protection. Since it’s very difficult to put them over staked tomatoes, we usually concentrate on saving the younger crops. Most of the cool season crops can stand a light frost, although even the hardy ones can be damaged if temperatures drop too quickly.