Fruit Tree Not Fruiting?
Got a fruit tree with no fruit? What may be going on? Can anything induce fruiting?
It’s quite normal with fruit trees that you may need to wait a few years for them to start producing well. Fig trees can produce fruit within one year when rooted from a cutting, but sometimes it can also take a few years. Tissue culture fig trees are notorious for taking a number of years to set fruit, and trees grown from seed can take up to seven years to fruit. But what if your rooted cutting just never sets fruit even three or four years later? Let’s take a look into what may be going on!
In this season of articles on nutrients, it truly usually goes back to that. Nutrients may be off in some sort of way that is preventing fruiting. Note that we are not talking about those random variables such as getting a smyrna or San Pedro fig variety which require pollination to set main crop figs. Neither are we talking about insects or critters stealing young fruits. We are talking about a lack of fruit bud initiation or development on our trees.
Figs set main crop fruit on current year growth. Breba figs are set on the previous year’s growth. Both are dependent on shoot length, number of shoots, and number of nodes per shoot. This means we need a good amount of new vegetative growth each spring to be able to have fruit.
Problem No. 1: Not enough vegetative growth due to nutrients.
⌲ The fix: Root health, nutrients and enough water.
For root health, we want to make sure that the soil is loose, not tight or compacted, and that there is enough air. Gas exchange at the root zone is essential for healthy plants.
For potted trees, this means checking our particle sizes and materials. We want a balance between aerating materials and water retention. We also do not want decomposing matter at the roots. Applying microbial and mycorrhizal products help with root health as well.
For in-ground trees, this means ensuring microbes and beneficial fungi are present as they alter the structure of soil in a positive way. Applying things like JADAM Microbial Solution (JMS), sea salt sprays, mycorrhizal fungi, compost or compost teas, worm castings, fallen leaf litter, or wood chip mulch are all things that move our soil in the right direction. The microbes and top applied organic matter will help to loosen and fluff soil.
For both in-ground and potted trees, we need enough organic matter to hold on to nutrients and to support microbial life as it is the microbes that help to make nutrients available to plants and trees.
Organic matter is important for having a stable supply of phosphorus which helps with root growth and with nutrient transportation.
We also need to ensure that enough nutrients are present. A hidden hunger sign in fig trees is stunted growth. Many have a tendency to focus on nitrogen for vegetative growth, but other nutrients are important for this as well. If you are supplying nitrogen but not getting the shoot growth you want, consider if the other nutrients listed are being supplied as well.
For in-grounds, this may mean doing a soil test so you can see if any nutrients are lacking. It also means supporting microbial life to make those nutrients become plant-available, especially mycorrhizae.
Potted trees usually do not have a lot of mineral availability in the materials typically used for potting mix, they also have a limited amount of potting mix compared to an in-ground tree with an entire dirt system below it. It’s also very easy to wash nutrients out of pots since there is nothing to collect what moves downward and out of the holes. So potted trees will need nutrients applied regularly.
Nutrients that influence shoot length are:
Calcium
Nitrogen
Magnesium
Zinc
Copper
Boron
Kelp/Seaweed
Critical points of influence for vegetative growth are early spring, when your tree is coming out of dormancy, and also in late summer to early fall, when nutrients are being stored by your tree for next year’s growth. Fig trees also form both vegetative and fruiting buds in axils of leaves during the late summer and fall. So we want to ensure the above nutrients are supplied throughout spring and then for a short time before leaf fall and dormancy.
My go-tos for these nutrients are Fish Amino Acids (FAA), JADAM Liquid Fertilizer (JLF), seaweed, and solution-grade gypsum or water-soluble calcium.
Problem No. 2: Too much nitrogen.
⌲ The fix: Limit nitrogen.
Figs have a lower nitrogen requirement compared to other fruit trees and plants. They also can easily get stuck in vegetative mode with nitrogen. Nitrate can really exacerbate this.
Ammonium technically is the form of nitrogen that can support reproductive growth. However, because figs like and require a larger amount of calcium, the calcium can raise the pH in soils. Higher pH can convert ammonium into nitrate. Excess nitrate also elongates shoots so that node spacing is too far apart which will limit fruit yield. Excess ammonium on the other hand can lead to toxicity which causes poor root development and stunted growth. So with either form, excess nitrogen will not help with fruiting.
All of the above means we should choose products with lower nitrogen amounts rather than higher, or use the more balanced and regulated forms of nitrogen in organic matter. Nitrogen is used by plants to form amino acids. Going directly to amino acids is a great way to get the benefits. Things like Fish Amino Acids (FAA) or fish hydrolysate contain these in healthy amounts. Other products are on the market as well that use amino acids for nutrient absorption, such as BioAg Cal-Mino or corn steep liquor fertilizers. Compost, worm castings, and plant fermentations all contain healthy levels of nitrogen as well.
We also need to stop supplying nitrogen once we get to a certain point in the season. If using chemical forms of nitrogen, we should stop once we have achieved sufficient vegetative growth to allow for fruit production. For many, this should happen by late spring or early summer.
If we have an overapplication of nitrogen, applying carbohydrates, magnesium, and molybdenum can help a plant to utilize excess nitrogen. Carbohydrates can be blackstrap molasses or other carbohydrate products. Kelp/seaweed, Epsom salts, and micronutrients will also help.
Problem No. 3: Water imbalance.
⌲ The fix: Balance water supply.
Issues with water can limit growth, cause defoliation, problems with root health, and dehydration in stems. All of this can lead to fruit drop or lack of fruiting. Water also helps to make nutrients available.
Make sure your potting mix has a balance of water-retaining materials with aeration. Both too little and too much water can cause issue. Use wetting agents from time to time to prevent water phobia and to help with water retention.
Use mulch to help keep the soil surface cooler and to prevent evaporation.
Make sure your pot is large enough for your tree. This means if you wish to maintain your tree in a certain size of pot, you will need to prune your tree periodically to reduce top growth and roots, and you will need to refresh your potting mix from time to time. Excess roots without enough potting mix to hold water can make for huge watering requirements. Larger top growth also requires more water and more root development to support it. Keeping these in check is important if water needs have exceeded what we can supply.
Make sure to supply adequate amounts of water. If using irrigation, make sure it dispenses enough for your tree. Conversely, make sure to not overwater. Set timers to make sure watering happens and turn them off if getting a lot of rain.
Growing for high Brix plants can also help with increasing water retention abilities in plants. This means:
Using mineralized potting mixes, add Azomite or basalt along with granular slow slow-releasing calcium sources to your potting mixes.
Ensuring regular and consistent calcium availability. Calcium strengthens stems and the vascular system of plants, allowing water and minerals to be taken up more efficiently. The more efficiently water and minerals are assimilated by the plant, the higher the Brix.
Using amino acids instead of sodium-infused synthetic fertilizers which lower sugars. Amino acids are chelators which help plants to uptake minerals. They stimulate root cells to open up calcium ion channels, allowing calcium to be taken up many times faster than simple osmosis.
Using humic and fulvic acids which make trace minerals available. Since trace elements activate enzymes in plants, plants are then able to do more chemical reactions per second, resulting in higher Brix.
Avoiding excess magnesium, nitrogen, or phosphorus which eat up carbohydrates and lower sugars.
Using seaweed which contains mannitol, a sugar that chelates micronutrients and makes them plant available. It also stimulates root growth which makes for more surface area to take up water and nutrients. It also contains potassium which helps with sugar transport in plants.
Blackstrap molasses can also help to raise Brix levels because of its micronutrient and potassium content. The sugars in it also help to feed and stimulate microbes.
Applying limited applications of boron which helps with both sugar and calcium transport.
Ensuring good microbial life in the soil to make minerals available, including mycorrhizae. Healthy plants absorb upwards of 80% of all their total nutrients from both soil and atmosphere through biology, according to John Kempf.
Problem No. 4: Over or under-pruning.
⌲ The fix: Moderate yearly pruning.
Figs fruit main crop on current year growth as stated above. If we are in the habit of doing heading cuts, we have taken away the tree’s nutrient loaded buds for stems, leaves, and fruits for the next season. This means the tree has also lost its source of photosynthetic energy. As such, it effectively puts the tree into survival mode and it will focus a lot on vegetative growth the next season so that it can have adequate energy and sugars for the existing root system, for stem growth for nutrient transport, and then later for fruiting. A heading cut can hinder fruiting for a season or two, though may be necessary to “rejuvenate” an older tree that no longer produces.
The other problem could be under-pruning, this is especially so if the tree is potted. The roots can only sustain so much top growth and the size of the pot will dictate the size of the rootball. Once it has reached its limit, top growth can slow down by quite a bit. Less vegetative growth means less fruit. Keeping potted trees pruned annually means that we won’t exceed the capacity of the root system and it will allow for some vegetative growth the next season. In many cases, a moderate pruning is sufficient. This means pruning for air flow, eliminating crossing branches and branches too close together. Branches can also be pruned down in length leaving about 3-4 buds. Some may prune a little more if they need to store their trees for winter. Others may prune less if they are focusing on breba crop.
It should be noted as well that when trees are left outside year-round and if you live in an area prone to late frosts, you may wish to only prune lightly. It’s been my experience that trees woken up early by warm weather and then subjected to a late frost or freeze can experience quite a bit of dieback. If you have already pruned heavily, this doesn’t leave very much for a tree to grow back from and it may have to grow new shoots from the roots. This can also delay fruiting for a season.
Other fruit trees may need different methods of pruning and it’s recommended to look up methods specific to the type of tree you are working with as the above is mostly geared towards figs.
Things that stimulate fruiting
There are certain tricks people have used that can stimulate fruiting. This can be especially helpful if a tree has gotten stuck in vegetative mode. It should be noted though that these are for all fruiting plants and not fig trees in general. So how figs will react is unknown for a couple.
Fruit Stimulant No. 1: Calcium
Fig trees are calcium lovers. Calcium supports both vegetative and reproductive growth. It is also a cytokinin (reproductive hormone) stimulant and shortens node spacing, allowing more spots for fruits. Using calcium as our primary growth pusher makes a lot of sense because it won’t cause vegetative dominance like nitrogen can. Using adequate calcium will also help to promote cytokinin which will stimulate fruit production. Sometimes you will hear of fig growers pinching tips to limit the auxin hormone which drives vegetative growth and is abundant in tips. However, instead of pinching, you can just focus on the nutrients that support reproductive hormones. I love water-soluble calcium in the form of vinegar extracts or solution-grade gypsum.
Low pH calcium inputs seem to have better uptake in some plants than inputs with higher pH. So the calcium acetate in vinegar extracted calcium is great for this; citric acid is another way to lower pH with calcium. Amino acids also help with calcium uptake and so giving calcium with something like fish hydolysate or using an amino acid complexed calcium product can be useful. Fulvic acid, (not humic acid,) can also help with calcium uptake.
Fruit Stimulant No. 2: Manganese & Phosphorus
Manganese and phosphorus help to drive bud initiation. Because both vegetative and reproductive growth are happening all of the time, very small nutrient changes can flip the switch to fruiting. If we have an overapplication of nitrogen giving us vegetative dominance, it is said a single foliar spray or two of manganese and phosphorus can change to reproductive dominance in some plants. In tomatoes, you can see flowers within 7-10 days after the right foliar application.
Can this help with figs? I don’t know, but it seems worthy to mention as these nutrients will affect reproduction regardless of the type of plant. Now remember, figs do not have a large phosphorus requirement. So this does not require regular, ongoing applications of anything like Bloom Boost type products. This is just one or two well-timed foliar applications.
(Need a quick phosphorus foliar spray? Some recommend grabbing a can of Coca-Cola! Dilute it by using four to six ounces per gallon of water and spray it on.)
Fruit Stimulant No. 3: Acetic acid
Acetic acid can trigger the development of reproductive buds. During periods of time when we normally have bud initiation, applying apple cider vinegar in a foliar spray can help to trigger bud formation in a tree that seems hesitant to fruit. As long as the needed vegetative growth is present, this could help to stimulate fruiting. The apple cider vinegar should be applied at rates of two to four ounces per gallon of solution.
Again, I think it’s useful to point to vinegar extractions of calcium or other minerals which utilize apple cider vinegar. It’s like a two-in-one combo for encouraging fruiting.
I hope these suggestions gave some ideas for what may be going on with your fruitless fig trees. After all, the goal is to eat yummy figs each year, we aren’t going for ornamental right?? May you have tons of fruit filling your baskets with these or other methods. Until next time fig friends!
Have a tip for stimulating fruiting? Feel free to share in the comments below. ⇣⇣⇣
