Proper Planting in South Florida

As published in the Miami Herald

There are many questions when it comes to planting a new tree or shrub. How large should the hole be? Is it necessary to amend the soil or to add fertilizer? How often should a new planting be watered? What type of mulch should be used? The answers to these questions are simple and can generally be applied to most new plantings. 

Your first step in planting is to dig a hole for your plant. The hole should be dug just as deep and slightly wider than the container of the tree or shrub being planted. If the soil is very rocky, try to break up the surrounding soil so the roots have somewhere to grow. A pick-axe is generally the best tool to dig through rocky terrain. The main thing to remember when planting is to plant the tree at the proper level. The roots of the tree should all be under ground and the trunk should be above ground. Placing a trunk below the soil line can cause the trunk to rot or encourage severe nutrient deficiencies and general poor growth. Usually planting the tree at the same depth it was in the container will suffice, but always check to make sure it wasn’t planted too low or too high in the container.  

Dig a hole a bit larger than the rootball.

Amending soil is generally unnecessary. Any amount of peat or potting soil placed within the planting hole of your newly planted tree can result in problems difficult to diagnose and correct. Amended soil will also have a different drying rate from the native soil around it. It is often the case that the amended hole will be dry when the surrounding ground is wet. Furthermore, a plant’s roots tend to stay in augmented soil and not explore the surrounding native soil. This creates a container effect. Fertilizing at the time of planting should also be avoided. When a tree is planted in the ground, its roots are not ready to absorb nutrients which may cause root burn. The tree should have produced one to two flushes of new growth before any fertilizer is added.  

Place the plant at proper level.

Watering

Watering should begin at the time of planting and continue until the tree or shrub is established. A planting is considered established after two to three flushes of new growth. 

Proper watering of a new planting is crucial. Too much or too little water can kill a new planting and is one of the top reasons for new plant mortality. A proper watering schedule will keep new plantings growing and help to quickly establish your tree or shrub.  

New plantings should be watered immediately after they are placed in the ground. Waterings should be thorough, causing any air pockets in the soil to collapse. The soil should be tamped down gently at this time to further insure the removal of air pockets. Be careful not to water your plant too often. Over-watering a tree can be just as deadly as not watering a tree at all. The best way to judge if a new planting needs water is to check the soil with your finger to see if it is dry. Water for the first week, then at steady increments: switch to watering every other day, then every three days and finally once a week until the tree is no longer dependent on your watering. Decreasing your watering will force the plant’s roots to store more water as well as extend out further from the base of the tree. Planting during the rainy season (late May to early October) is by far the best way to easily establish new plantings. If you time your plantings to be completed by the first of June, you will significantly decrease your hand watering because natural rains will take care of most of your plant’s water needs and will decrease the amount of time needed to establish your plants. Smaller trees will require significantly less time to establish than larger trees and will require less hand watering over time. Most small plantings are established within three to six months from time of planting.

Backfill the native soil.

Irrigation systems are not a necessary component of the South Florida garden and are used primarily for keeping lawns lush in the dry winter months. It is best to conserve water and let lawns go brown in the winter and spring months. Lawns will again turn green in the wet summer months. A wide variety of tropical fruits require a dry season to flower and fruit prolifically and irrigation systems actually disrupt their blooming schedule. 

Mulching

After a tree has been planted and watered, mulch should always be added to complete the planting. Mulch is highly beneficial. It can beautify your planting, suppress weeds, add nutrients to soil, slightly alter pH, protect new plantings, retain moisture and even turn stone to soil.  

Protection:  One of the greatest benefits of using mulch is its ability to protect both new and established plantings from damage. Public enemy number one of newly planted trees is the string trimmer. If you have a newly planted tree that is not growing well, check for nicks and cuts around the base of the tree caused by accidental strikes from the string trimmer. When a tree’s bark is damaged, the tree’s transportation system and food supply are damaged. The roots cannot get energy from the leaves and the tree may stop growing or sicken and die. A ring of mulch around a newly planted tree or an established tree will protect the tree from being damaged. Keep mulch away from the trunk to avoid disease.  

Stone to Soil:  If you live in South Florida, you know that our soil consists of limestone or builder’s fill (crushed limestone) with the occasional pocket of sand, marl or muck. Residents of South Florida often manage to create beautiful landscapes by choosing plants adapted to growing in limestone or by altering the soil. Rocky soil can be altered by applying mulch. Mulch begins to solve poor soil problems from the moment it begins to decompose. The more mulch you put down, the better it is for your plants in the long run. The more times you mulch a year, the better it is for your soil. Over time, your applications of mulch will do several things. The acidic mulch will wear away at the limestone helping to create crevices and pockets in the rock which will be exploited by the roots of your landscape. Mulch can also provide a lower pH environment, which is more conducive to the uptake of nutrients, for the roots. The naturally high pH (averaging 7.8-8.1) of our limestone based soil makes micronutrients such as iron and manganese unavailable to plants. Your applications of mulch will decompose into rich, organic soil and will provide nutrients to your plants. Mulch will also act as a sponge, absorbing water and nutrients that would normally run off of the limestone and into the aquifer. The ability of mulch to hold on to nutrients will allow you to apply less fertilizer and water while maintaining a high level of nutrition in your garden. 

Application:  Each application of mulch should be at depth of six to ten inches. Never mulch next to the base of a plant as this can cause trunk and root diseases and overall health problems. Mulching too high next to plants can be avoided by simply pulling mulch away from a plant’s base in a ring after the mulch has been applied. Extend mulch beds or rings laterally to a tree’s furthest reaching limbs (the drip-line). The greatest concentration of feeder roots occur at this point. 

Types:  There are many different types of mulch available to the homeowner. Melaleuca and Eucalyptus mulch are the most environmentally friendly as they do not use forest trees such as cypress to produce their mulch. Leafy mulch will decompose faster than woody mulch. Almost any mulch is beneficial to your plantings. Do not be afraid of mulch from tree trimmers. Worries of “weed seed” being delivered to your yard by deliveries of mulch are often exaggerated. Invasive seeds hidden in a mulch pile can be easily destroyed by composting the mulch before applying or by simply picking the weeds as they appear. However, it is possible to bring in citrus canker in tree-trimmed mulch and citrus owners should be wary of mulch from an unknown source. 

Your final step is to mulch and water the planting.

Proper planting, watering and mulching is crucial to the success of your new plantings and will pay benefits throughout the life of the plant. For more information on gardening in South Florida, visit www.fairchildgarden.org/gardening.