Well, its officially summer here in South Florida as the daily rain really picks up and humidity is at 90% as early as 6am. If you have lingering spring veggie plants in your raised beds you might see them start to really deteriorate now, since many crops we rely on during the winter and spring don't thrive in such intense wet and humid situations. Thats ok though, it's all part of the cycle of life in your garden. If you've planted any tropical climate perennials you might see them start to really take off and make new growth quickly in response to the added rainfall and long summer days. Did you know that rain water contains vital nutrients that plants need for growth, like nitrogen? Yup. Nitrates are the most easily absorbed form of nitrogen for plants, and thats whats in our atmosphere. When rainwater is formed and falls through the air it absorbs them, and oxygen (which your plants need in their root systems in order to absorb other nutrients), and delivers those two key elements to your plants when they get rained on.
Banana plants are really good reminders of how important rainwater is for plants, because they are literally designed to be like big rainwater catchment systems. New banana leaves emerge from the center of the plant wrapped around themselves like a straw (so they can slurp up rainwater when available) and the mature leaves are arched like an umbrella, so that rainwater can be led either inwards to the trunk where it then drips down to the base of the plant, or outward to drip off the end of the leaf and end up watering the "drip line" of the tree. Bananas grow in clumps, so with each plant performing this rainwater catchment action they all help water each other, and their leaves overlap and create layers of shade which allows for the soil around the roots to remain nice and moist even when it hasn't rained for days. "Companion planting" is a term you might be familiar with that gardeners learn about early on when they are looking for ways to keep their plants pest free. Theres a common belief that marigolds will keep pests away from your tomatoes, and while we are a bit skeptical of such cut and dry approaches to companion planting theres a lot to be said for approaching the design of a planting with the unique qualities and needs of each plant being taken into consideration. For example, what plants would enjoy being in the particularly wet and moist area within the drip line of a mature banana plant? In the planting pictured below we included lemongrass, ginger, spicy peppers, and sweet potatoes on the sunny side of a banana clump, so that they would get a good amount of sun during the morning & mid day, and then some much needed shade towards the end of the day, and they would have access to the water collecting and storing capabilities of the bananas.
A perennial food system like this is referred to as a "plant guild" and on a larger scale its called a "food forest". Someone designing a planting like this will take a number of things into consideration when choosing what plants to include, but the main way that the plants are organized are in terms of what space they take up in relation to each other, and gardeners look to the way that a forest naturally organizes itself for inspiration. As you walk through the forest you can notice many distinct layers of foliage and different types of plants thriving at each layer. The tallest plants are trees that use their trunks to reach for the sky which is where they make their leaves, because thats where the most sunlight is. Under them are layers of smaller trees and herbaceous shrubs that can thrive in the dappled sunlight provided by the large trees. And down on the ground there are smaller flowering plants, crawling plants, vining plants and a most important element: dead plants and decaying plant material.
While the above diagram is useful for seeing the category of plants laid out visually, as a tropical gardener you definitely need to ignore the examples of plants for each category :) Your palette of plants is very unique for North American gardeners because your perennial plants need to like heavy rainfall, high humidity and lots of high temperatures too. If you are looking for inspiration for what type of plants to include you can start by looking to similar climates throughout the world to see what gardeners there are growing successfully. Some climates that are most similar to ours are that in coastal Hawaii, parts of Australia, Southeast Asia, India, coastal parts of Mexico, North Africa and also places a bit closer to us like the Caribbean, Cuba & Puerto Rico. Some of you reading this might be familiar with the concept of Plant Hardiness Zones but you've maybe only seen the map of the United states separated into colorful zones that have similar climates, so here is the map of the entire globe and its corresponding zones. We are in Zone 10, which is the bright yellow one, which as you can see is spread out throughout the world.
Here are some examples of a small and a medium tropical perennial plant guild with species that thrive in South Florida.
This small guild has one large midstory plant which is a papaya tree. We like to encourage people to skip the overstory tree when planting a small system because those trees get so large that even after just a few short seasons they will create so much shade and canopy cover that little can thrive around their base, and also in a suburban backyard sometimes just one Mango, Avocado or Mamey tree can take up most of the yard when mature! So, we like to skip that layer and start with the mid story, which should be made up of small or dwarf variety fruit trees, like bananas, starfruit, mulberries, guava & papayas. Under the papaya tree we have chosen to plant a cranberry hibiscus as the shrub layer, which is a really beautiful plant with edible deep purple leaves. Up next is the herbaceous layer which can be made up of both annual & perennial plants, like lemongrass, ginger, turmeric, rosemary, spicy peppers, eggplants, and a bunch of other climate appropriate plants that ideally get no taller than your waist. The final layer is that of the ground and ground covers. As a way of simulating the environment on the forest floor we add a thick layer of natural wood mulch (that is, not bagged mulch from a store but material made by tree trimmers doing work in your area on a variety of tree species) around all of the plants to protect the soil from drying out and to create an environment where things are constantly decomposing and composting. Trees and other perennial plants thrive in an environment where they can have fungal networks existing within their roots, and fungus' like decomposing leaves and woody material, which is why so many mushrooms are found in forested areas.
The system pictured above is just a bit larger and includes some more diversity because of its scale. The midstory planting is made up of a dwarf banana variety and a guava tree, planted far enough apart for them to both have the space to grow comfortably even when mature (about 10 feet apart). Under them a roselle hibiscus and some edible leaf taro make up the herbaceous layer and get about as tall and wide as a human with their arms outstretched. The herbaceous layer is made up of moujean tea, native to the Bahamas and used to make tea, spicy peppers and garlic chives, which have amazingly resilient root systems that allow them to grow and regrow year round. The final layer of mulch is topped with a groundcover, which is a plant that grows along the ground and spreads itself as it does so, eventually making a matt of foliage that you can walk on. Our favorite edible ground cover is sweet potato, but non-edible plants are more than welcome in plant guilds too! Perennial peanut, puffball mimosa, and frogfruit are our favorite useful (but not edible) ground cover options.
If you have the space in your yard and the desire in your heart to include a perennial food system in your garden plan, we definitely recommend giving it a try! Now is the best time of year to plant something like this because of the rain & humidity. You'll be amazed at how fast your plants grow if planted in the rainy season. Do yourself a favor and plant a banana before leaving town for a few weeks. When you come back home you can marvel at how quickly its grown in such a short time and with no tending from you.
And if you want more information consider watching our Summer Gardening Workshop for FREE on YouTube.