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In the age of instant gratification, fruit ordered on your grocery delivery app might be delivered in a matter of hours. However in the natural world plants still abide by the “Laws of Nature”. So when we hear the frequently asked question of “How long will it be until my tree produces fruit?” Or “Why hasn’t my tree started flowering or fruiting yet?” our first question is, “Well, how long ago did you plant your tree?” And while one to seven years might seem like a long time on our human time scale, consider the life cycle of your precious fruit tree…
Let’s begin by going back in time at least 5000 years ago, to a time before humans reigned supreme. Now imagine for a minute that you are actually the spry little Apple tree in the fertile valleys of Central Asia or perhaps a freshly sprouted Pawpaw tree in the lush floodplain of the Potomac River. Your first thoughts as a newly sprouted tree are not on “the act”, called procreation, which is, in this case, the act of making fruit & seeds. Instead, your thoughts are on establishing a deep root system, creating branches and soaking up as much sunlight as possible. While you get a foothold in the rhizosphere and stake your place below and above the ground you claim your niche. A young tree is learning about sun exposure, soil depth, seasonal changes, nutrient availability, rain cycles and so on. For maybe even ten years a young tree might not make any fruit. This is because the process of making a fruit is very energy intensive. As a young tree trying to survive in the natural world you can’t afford to flower, fruit and drain all your seasonal energy reserves when young. Yet just like every other species, whether plant or animal, your ultimate goal is sexual reproduction. So, conditions have to be just right and you have to be ready otherwise you won’t be able to ripen fruit and create offspring in the form of seeds.
Now let’s fast forward to modern times when the all the fine fruited flora of the world has been moved around far outside their native climates. Fruiting plants are being asked, urged, begged and even engineered by technological advanced bipedal mammals (humans) to produce as much of their sweet juicy nutritional fruit as possible. (A lot of pressure to be under, huh?) Although plants do their best to adapt to every situation, there are definitely limits to a plants ability to change, thrive and reproduce. Ensuring bumper crops or more precisely, consistent fruiting requires effort and understanding. Let’s find out what it takes to make human frugivores happy.
What exactly does it take for a fruit tree to make big juicy fruit early in its life and then reliably season after season?
The most obvious start to discussing fruit is of course pollination! Many species require pollination in order to set fruit. Two types of flowers exist that need pollination. First, flowers that are self-incompatible meaning they are unable to accept pollen that is genetically identical to themselves, like Pawpaw Trees. The second type is called dioecious, meaning, having male and female flowers on separate plants, like Sea berry bushes. Plants evolved with a variety of pollination strategies. A plant that is self-fertile goes through life only pollinating itself and this is called inbreeding. This type of pollination ultimately limits the genetic diversity within its offspring. When plants are cross-pollinated by another variety the genetic diversity has been mixed and the pollen will fertilize the ovules and your desired fruit can begin to take form. Fertilization or cross-pollination is required and that is what produces big juicy fruits like Apples, Pears, Plums, Cherries, and so on.
Cross-pollination is not as simple as just planting two different varieties of your favorite Apple or Pear tree. First, you have to be sure the trees flower at the same time. If the tree’s flowers aren’t open and receptive at the same time or at least sufficiently overlapping then no pollination will occur. Once you’re sure flowering occurs at the same time then, you have to be sure they are compatible pollenizers for each other. The compatibility issue can get a little tricky with the number of chromosomes making a difference. Luckily, there are online pollination charts that provide detailed information. Useful charts will reference flowering time and compatibility. You can find local resources like local university extension agencies for information. Online fruit tree pollination charts will bring up a wealth of information related to cross-pollination. Often it takes decades of scientific observation from university research programs to determine reliable compatibility and publish these pollination charts. One such research station is at Washington State University and One Green World has delivered many of the fruit trees to be studied and recorded. Here you can find the results WSU Fruit Tree Project
For dioecious fruiting plants such as Kiwis, Sea Berry, Schisandra, and others a male plant is required to fertilize the female plants and achieve pollination. The male plant will produce no fruit. Males have flowers with stamens that produce only pollen which is needed to pollinate the female ovules. Typically, one male plant will pollinate up to about 7 female plants. Within dioecious species, we often find rare hermaphrodites that have both male and female flowers on the same plant. This makes it possible for one plant setting fruit. These special self-fertile dioecious plants like Eastern Prince Schisandra and Issai Hardy Kiwi are examples of hermaphrodites.
The chilling requirement of a plant is the minimum period of cold weather after which a fruit-bearing tree will blossom. It is often expressed in chill hours, which can be calculated in different ways, all of which essentially involves adding up the total amount of time in a winter spent at certain temperatures. Usually, chill hours are added up as the number of winter hours with temps between 32 and 45 degrees Fahrenheit. Fruit trees have different chill requirements and each variety needs to be assured that winter (as far as it is concerned) has come and gone and it is now time to produce fruit. Species from cooler climates require a higher number of chill hours to know that winter has passed and it’s time to flower, otherwise, a warm spell in winter or even spring could lead to damage of emerging buds. Thankfully many low chill varieties have been developed for warmer climates. Growers in warm temperate, subtropical or even tropical climates can grow cold climate fruit trees like Apples. If you want to get really technical and learn the different ways to count chill hours or just check your varieties requirements then go to UC Davis Fruit Tree Chilling Accumulation Models
Fertility and Soil
Many gardeners are guilty of loving their plant to death with fertilizers and an ever-expanding selection of soil amendments. Another common method of too much love is overwatering. For a young fruit tree, all that love might actually provide too much of a “good thing” in their new home. An excess of Nitrogen can cause a tree to produce a bountiful abundance of lush deep green growth but no fruits for a few years. Excess nitrogen is usually the primary culprit as we often hear of gardeners with explosive young vegetative growth on their tree and then a lack of flowering and fruiting for a few years. The theory behind this is that trees, especially young ones, that are happily growing in a vegetative state don’t feel the pressure to reproduce sexually. They can happily go on growing and reaching for the sky as they strain to get above any other competitors that may be growing next to them in order to swallow up that precious sunlight. One remedy for too much Nitrogen is to add Phosphorous amendments like Epsom Salts or Fish Bone Meal. We recommend planting right in your native soil and then top dressing with compost, fertilizers, amendments, minerals, and micro-nutrients. Backyard Orchardist is a great book for beginners and experienced alike. Penn State has an incredible resource site, especially for the Eastern US growers. Check out Penn State Extension agency for links, videos, and up to date research on growing fruiting plants. If you really want to nerd out on soil and fertility check out the USDA’s powerful mapping tool. You can dial in your growing area and go deep into the soil food web. Click the round green button that says Start WSS here on this page Web Soil Survey
Pruning and Heading Back New Growth
Besides cutting back on nitrogen-rich fertilizers another strategy that many folks have found useful is to prune your tree. Don’t be afraid to make cuts on your tree! “Prunephobes eat no prunes” as they say. We’ve found that summer pruning on new growth that was headed back by a quarter to a third of its length in July and August often causes the young branch to begin creating flowers or fruiting spurs sooner. This is especially true with Hardy Kiwis, so for anyone wondering why their kiwi hasn’t fruited yet, try summer pruning! One theory on why this stimulates fruiting is that we are mimicking an herbivore’s browsing. When we prune this sends a message to the plant that it is time to start creating seeds and fruit. Read UC Davis Home Orchard’s “Ten Basics Of When And How To Prune Fruit Trees”
We all know what stress can do, it affects every living organism. The truth is stressors can be both good and bad. Good stress makes one stronger while bad stress can cause lasting damage. In a controlled way, pruning is a stressor that shapes fruit production. So with plants how do you draw the line? Old time remedies range from hitting your tree with a broom to more recent interpretations involving ramming the tree with a tractor! Old folk wisely tell you to do it in the middle of the night so your neighbors don’t think you’re crazy. Technique aside the idea here is that the stress caused by mechanical damage can stimulate the tree into fruiting. We have witnessed accidents, for example, when a vehicle hits a tree knocking it over but not killing it. We suggested pushing it upright and supporting. Later we find out the tree is now thriving and making too much fruit! While some folks have found success with this method we caution against creating any serious mechanical damage. We have found that regular pruning can be just as helpful in encouraging your tree to set consistently heavy crops. WSU has a great article from their orchard program called Environmental Stress Management.
Stressors from the previous growing season can be another factor contributing to how your tree flowers and fruits in the current season. If a tree was stressed for any reason, be it diseases, winter freeze or spring frost damage, lack of water, sunlight or nutrient deficiency in the previous growing season then it will quite likely set less fruit or no fruit the following season. We often talk to customers who fail to water their trees at all in our dry summers and are surprised when their tree stops setting fruit. Given that the flowers you see in the spring were created during the previous year’s growing season it should come as no surprise that a stressed tree would not create as many of those energy intensive flower buds. We recommend deep weekly watering during the summer for at least 3 years after planting.
A common stressor for many apple varieties and other trees to some extent is overbearing in a single year which causes little to no fruit the next year, what’s called a biennial bearing cycle. This boom and bust cycle can easily be broken by thinning the fruit in the heavy years to balance out the bearing cycle. Often these trees are stuck in this on/off cycle baffling the homeowners. Penn State Extension has excellent related resources on renovating old fruit trees on a page called balancing Apple and Pear tree production in home plantings.
Grafted vs Seedling
Plants grown from seeds can provide growers with another lesson in patience as fruiting plants grown from seed often take longer to fruit than those that are grafted or rooted from cuttings of mature fruiting plants. When we graft or root a branch off a mature plant we are propagating material that is already “pre-programmed” to be fruit-bearing. You often see grafted trees and plants grown from cuttings flowering as soon as their buds open. While you wouldn’t want a newly propagated tree to send its energy into making fruits it clearly illustrates how ready they are to do so. The advantage of growing seedlings is the ease of propagation and genetic diversity. A plant grown from seed is genetically unique and in order to discover new varieties or hybrids, we must grow seedlings. The professional plant breeders who are growing out seedling for research trials will graft the young seedlings on to dwarfing rootstock which causes the “seedling” if you can still call it that, to produce fruit sooner. This saves the plant breeder years of time by effectively fast forwarding through years of vegetative growth and being able to evaluate the fruit quality sooner.
Why do my new fruits begin to grow then shrivel and fall off?
Aborted fruits is another common issue for home orchardists and is a frequent common question we receive. Many folks see their trees produce a profusion of beautiful flowers only to be let down when the tiny fruit shrivels up and drop off. The truth is plants are unburdened by anything but natural law so aborting some or all of their fruit if conditions are not right is a very common and natural phenomenon. All the factors previously discussed can contribute to this and alleviating those issues almost always cures the aborted fruit problem, but if it persists consider getting a soil test done to assure your tree is receiving proper nutrition. Locally you can find companies that provide soil testing and soil amendment recommendations for a wide variety of fruiting crops. If you check out the NRCS website you can learn all about soil testing here at Small Scale Solutions for your Farm.
Hopefully, this will help guide you with information to alleviate any non-fruiting plant issues you may have and provide you with the knowledge to cultivate bountiful harvests. We hope you receive “olive” the fruit your heart desires in this coming growing season.
Thanks for reading! As promised here is your $5 off coupon for purchases of $25 or more. Use the coupon code: Firstfruit