How Not To Kill Your Tropical Fruit Trees

Introduction

Mangos, Guavas and Avocado trees in California? Can it be done? Sure it can and is being done all over town. With a little planning and consideration to sun, wind, cold and watering you can grow numerous types of tropical and sub-tropical fruit plants and trees.

Many think that the summer heat is the main killer and reason you can't grow many tropical plants in California. Well, have you ever been to India, Thailand or even Florida, it is brutally hot in the summer, factor in the humidity and well you know. Though summer sun and heat is a factor, the main killer is wind and cold, second biggest killer is under watering newly planted trees. The presumption when someone says California climate is to think of the pleasant southern costal area and beaches and how easy plants grow there. Apart from the coastal area, the truth is that California has a diverse climate, from searing deserts to snowy mountains and all the challenges that come with growing sub-tropical plants. Tropical trees take time to mature and take on going care. With owners changing hands so frequently, chances are the new residents will not have the same landscape desires as the previous ones and the plant is removed or dies from lack of care, this is less evident in the older sections of town with mature landscapes.

The following is a general tropical planting guide. The advise is derived from years of trial and error, reading of numerous books, web sites and the advise and guidance of many friends who share the passion and desire to grow these plants in the arid desert.

Well if you are ready, lets get started, however before we do let me make this statement. Gardeners have been growing and killing plants for as long as anyone knows, yes desert plants too. No one is exempt from this fact and try as you might it cannot be avoided. We as gardeners can control only a small fraction of what a plant requires to survive. Soil condition, drainage, humidity, heat, cold, diseases, pests, winds, pollination are only a few of of the many obstacles that stand in our way and many well beyond our control. I will also say that every gardener, novice or experienced has an opinion, and what works in one persons garden does not necessarily work for another. With that in mind I encourage you to follow the links on our website, buy or borrow the various books listed and conduct research of your own using the search engine of your choice, then modify the information as necessary to fit your individual planting situation.

Location and Planting

For most plants, pick a good location near your house and preferably under a roof overhang. The idea here is that your home will help provide heat during the winter and the overhang may prevent cold from settling on your plants during the night. Planting under the canopy of another larger tree can also provide the same benefit in some cases.  Best, but not the only time to plant is March - October, (yes that means you can plant in the middle of July, just wear a hat, put on sunscreen and drink plenty of water).  Loosen the soil several feet (3'-4') in diameter from where you are going to plant. Dig a hole only as deep as the root ball, no lower, and about twice as wide. Fill the hole about half full with water and let drain. This is a good test for drainage but will also provide the plant with a water storage it can use later. Next cut away the bottom of the nursery container and place the plant in the hole, carefully cut up along the side of the pot and remove it. Mix the removed soil at a rate of 50/50 with compost and backfill the hole. Now water well.  With the remaining soil build a  berm around the plant at least 4" high and fill with water. Once that has drained apply a layer of compost of again at least 4" deep around the plant but about a foot away from the trunk of the tree.

Watering

When you first plant your tree keep the root ball consistently moist. This may mean having to water two or three times a day during the hotter months. Under watering is one of the top reasons young tropical trees die. Did you ever have a gold fish when you were a kid? If you did, the sales clerk probably told you to be careful and not to over feed the fish. Well I bet nothing was said  about under feeding and so is the case about tropical fruit trees. A lot of advise around the valley from various sources warns gardeners not to over water but nothing said about the dangers of under watering, more correctly the advise should be to water properly. Many gardeners never adjust their drip systems after their landscapes are planted and continue to be watering mature landscapes everyday for several minutes just like the landscaper set it originally. Care should be given to water correctly for the size, type of tree and the season.  Once established, (usually a year or after the first summer) water deeply to 3' and infrequently. Deep infrequent watering is very important to tropical and subtropical fruit trees as most are very susceptible to the salts in the water and deep watering pushes the salts down away from the roots. Water established trees twice a week during the summer and once or twice a month during the winter. Also placement of the drip emitter or hose is important. Feeder roots are usually 18" deep and extend to the dripline, (the otter most area of the canopy). If you are still watering an established tree at the truck you are wasting water since the plant cannot use it. Water and fertilize at the drip line only once established. Also some varieties should not be watered at all during the winter, see specific planting guides for those trees.

Care and Frost Protection

As mentioned before, cold is the leading killer of tropical type plants as is the case with many plants. Have you ever wondered why a plants hardiness is calculated by the minimum temperature a healthy mature tree can withstand and not the heat. Because simply, cold kills more plants than heat. Here in the inland our hardiness zone is Zone 9A-9B. Fortunately temperatures near or below freezing are in the wee hours of the morning, usually the few hours just before sunrise. You can protect your trees on cold nights when the temperature is expected to be in the mid 30's or lower by using any number of items found around the house. You can cover your trees with cardboard, blankets, frost fabric or burlap, just remember to remove these in the morning when it warms up as it can have an opposite effect. Plastic is not a good insulator and can cause more harm than good. Lights also are a great heat source and keeps the air moving and preventing it from settling. Speaking of lights, the start of the coldest nights typically coincide with the holidays, so if you are hanging Christmas lights anyway, remember to decorate your tropical trees too. To provide adequate heat you will need to use the old fashioned lights with the regular bulbs, the cute tiny twinkling lights won't do. Remember when you look up a plants hardiness it is referring to a mature healthy tree, young trees and plants will need protection at higher cold temperatures. The time to plan is before a frost, once a plant as been exposed, the damage is usually done and it is too late. Also there are many micro climates through out the valley and even in your own yard. Try to know the particulars of your garden as the frost warnings on the news are usually for the airport or other reporting station and your yard may very well be several degrees higher or lower than what is predicted. Backyards with low spots or enclosed by block fences may very well trap cold air. Know your yard and act accordingly.

Fertilizing

Don't ever use chemical fertilizers on tropical and subtropical fruit trees the first year, safer is to wait two years. I only use compost and can't say enough good things about it. Compost is organic and as it breaks down it provides a slow steady stream of nutrients. Compost also enriches the soil, helps break down caliche, encourages beneficial microbes, maintains soil and is cheap and easy to use. Just pour a layer of 4 inches or more around the tree being careful to keep it about a foot from the trunk. What can be easier, plus it is natural. Some additional feeding is necessary for proper fruit production in some plants such a bananas. Just remember if you use a chemical fertilizer less is more. I suggest that you apply at a rate diluted to 50% what is called for on the packaging. Some plants attempt to feed themselves such as avocados. The plant is evergreen but regularly drops leaves, instead of raking up the fallen leaves bunch them up under the tree but not against the trunk. This is what they do in the large avocado orchards in Florida and California. If one was to walk amongst the trees you would be ankle high in leaf litter. What ever you decide, remember to fertilize at the drip line, there are no feeder roots at the trunk and less is more with any commercial chemical fertilizer.

Soil

Our desert soil is actually fairly high in many nutrients and minerals. This is evident by the water deposits found around your faucets and spigots. What our soil is deficient in is organic matter and nitrogen, as well frequent watering depletes and washes away many of these minerals over time. Amend the soil with compost, it is cheap and goes along way in the garden. There are also many organic solutions to these deficiencies, and a search on the internet will reveal many options, however if you want to use store bought chemical fertilizers do so sparingly and not for at least the first year.

Winds

High winds whether during the winter or monsoon are equally damaging, up rooting trees and destroying leaves. Wonder where the name tropical storms come from, well from the tropics. Unlike our climate where cold is the main killer, in the tropics it is wind. Tropical storms cause millions of dollars of damage to plantation crops as well as the native plants each year and it can't be avoided. Have you ever seen pictures of tropical islands? Well in nature tropical plants grow in dense proximity to each other. The outer plants provide a wind barrier to the interior plants, yet there can always be damage, it is less severe by this form of grouping. Do what you can to protect your plants by either planting near your home or fences. Plant near other mature trees or stake them during stormy seasons, even plant wind breaks such as bamboo. You can't eliminate the treat but it can be minimized. As your tress and plants mature they will provide some protection for each other.

Sun and Heat

Just like infants, children and the elderly are more suspectable to heat stroke than healthy adults so are young or old fruit trees. A young tropical fruit tree planted in mid summer should be given some protection from the intensity of the summer sun. You can erect a temporary shade structure out of landscape poles and shade cloth or just use a beach umbrella, basically anything will do. Even a branch saved from pruning yours or your neighbors Palo Verde or Mesquite tree placed on the west side of your tropical fruit tree can block the intensity of the western sun. Once established you should be able to remove the shade with very little risk. With the many hours and days of sunshine in the Phoenix area you can safely plant many tropical trees that call for full sun under partial shade or filtered light and they will do fine. Bananas on the other hand need full sun to successfully flower and fruit. The same is not true for plants that call for shade for their entire lives as they will surly die in our direct son. Some plants such as avocados naturally grow in shade under the protection of the mother plant or tropical canopy and require several years of shade, after which they need full sun to flower and set fruit. See specific gardening advise for these plants.

Impatient Gardner

Everyone asks how soon they will be enjoying the fruits of their labor and certainly understandable. It shows you have interest in what you planted and are excited. Though most of the grafted varieties have the potential to produce fruit the first season after they are planted, some restraint should be exercised. Though grafting produces fruit many years sooner than most seedling varieties, the purpose of grafting a tree is so that it produces a specific fruit equal in quality to the parent plant. The first year or even two you should remove the buds (does not apply to bananas), so the plant puts most of its energy into developing a good root system and grows faster so that it can later support larger quantities of fruit. If you can bring your self to wait and resist the temptation to taste your first home grown exotic fruit you will be greatly rewarded later with a much healthier tree and larger abundance of fruit.

Awareness

The best guide to how your plant is doing and best chance to intervene with a potential problem is to get outside. Occasionally water with the hose. The time it takes to fill the basin of each plant will give you the opportunity to look the plant over. Your plant can tell you many things if you take time to look. The color of the leaves can indicate certain nutrient deviancies. Curling of the leaves depending on which direction can reveal over or under watering. Damage to the leaves or trunk can reveal pests or disease and all possibly give you enough time to seek advise and react. If you use a watering system such as drip emitters be advised they are not fool proof. Apart from the fact that the emitters have to be changed and adjusted yearly to coincide with your maturing tree they can also fail or become plugged, and a few days or weeks with out water might have an irreversible affect.

Learn

The further you take a plant from its native environment the more you need to know and try to mimic its ideal growing conditions and needs.  These are not plant and forget landscape trees and the only way you can hope to protect your investment is to learn as much as you can. Read books, browse the internet or join a gardening club, anything you do can only pay off in the long run. If you have success or failures don't be timid about sharing your experience, there are any number of gardening clubs and online forums. We can all benefit from the success and failures of others. Good luck and happy gardening!

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