As fall approaches, gardeners’ worries don’t seem to diminish; they increase almost like an avalanche. Once the topic of fall fertilize fruit trees comes up, the debate begins. Is fertilizer needed? What to fertilize, how to fertilize, does it work, and is spring fertilization better?
All of this is done here with great care not to hurt the feelings of those who advocate chemical fertilizers, and those who consider themselves opposed to introducing any chemicals into the soil, as we will try to understand today.
DO I NEED TO FERTILIZE IN THE FALL?
Let’s say that an apple tree, a big, powerful one, which gave us a beautiful harvest this year, has apparently taken all the known elements from the soil, nitrogen, phosphorus, and potassium, although in different amounts. They are certainly depleted and, leaving everything intact, does not enrich the soil with fertilizers and does not restore the disturbed balance. To be sure, a considerable number of trace elements are extracted from the soil, magnesium, calcium, and other similarly important substances. If you listen to logic, then in autumn the soil should also be enriched with both basic and trace elements. This improves the soil structure and creates more favorable conditions for the growth and development of useful soil microflora.
WHAT FERTILIZERS ARE USED FOR THE AUTUMN FERTILIZATION OF THE GARDEN?
Ideally, the list of fertilizers added to the soil in autumn cannot be called that many: it is phosphorus, potassium, wood ash, and organic fertilizers. As you already know, during autumn there is no need for nitrogen at all because it accelerates the growth process, there are fresh seedlings, which are easily killed by freezing in winter, and if they are not cut in spring, they begin to rot and weaken the immunity of the plant.
Let’s start with phosphorus fertilizers: they are mainly aimed at the full growth and development of the plant’s root system, accompanied, of course, by the accumulation of protein compounds and sugars in the cells.
In order to enrich your plants with phosphorus in autumn, you can use calcium mono and bis-per phosphate. The difference lies in the concentration of the active ingredient, i.e. phosphorus. These fertilizers can be in granular or powder form. That said, mineral fertilizers have proven to be very good in practice and are often used in small cottage lots and large industrial gardens.
Don’t forget that phosphorus is a slow-moving, water-insoluble substance, so it won’t be of much use if you just spread it into the tree bed circle in the fall. Many people even claim that applying this method in the fall has no effect at all. The best option is to embed calcium superphosphate into specially made cavities in the rootstock. The depth of such cavities should be 4-6inch (11-15 cm) for tree species and 3-3.5inch (8-9 cm) for berry shrubs.
When embedding phosphate fertilizer, it is best to set back 7-8inch (18-20 cm) from the main part of the trunk or shrub and make the embedment where the roots are sucked. One hole is not enough, you need to use a dose of 25-30 grams under the tree and 15-20 grams under an adult bush, distributed into several holes.
Fall application of potassium fertilizer improves the winter hardiness of all crops without exception and promotes the run-off of excess water from plant tissues.
One of the best fertilizers for trees and shrubs is potassium sulfate, also potassium sulfate, which does not contain any harmful potassium chloride. Both can be applied at a rate of 7-12 grams per square meter. It is recommended to loosen and water the soil well before adding the fertilizer.
If you decide to apply a combination of phosphorus and potassium fertilizer in the fall, we recommend it because the plants can absorb phosphorus better through potassium and are therefore more effective than if you had applied the fertilizer alone.
Of course, you can do the simpler thing and choose potassium chloride. However, to prevent root damage from chlorine, you must apply this fertilizer as early as possible so that the harmful chlorine has time to be washed into deeper soil layers by irrigation and rain before winter arrives and the soil freezes, making it inaccessible to the roots of cultivated plants.
Calcium-magnesium and phosphorus fertilizer – also good fall fertilizers, which, in addition to potassium, as you can see from the name, also contains magnesium and other essential elements for most tree and shrub plants. It is not recommended to apply this fertilizer dry. The best option – is to dissolve it in water and water their bushes and roots (15-18 grams per bucket of water for adult trees, 7-8 grams for adult shrubs – this is the normal amount of fertilizer at this time). For young plants, you can halve the dose. Don’t forget that if the soil in your location is light and sandy, you can always increase the dosage of magnesium by 25-30%.
A word or two about applying compound fertilizers in the fall. They have proven to be quite effective. For the most part, fall combined fertilizers are potash and phosphate, as we have already said, but there are also special fertilizers designed for fruit trees and berry bushes with the word “fall” on the package. The dosage applied is usually indicated on the packaging and must be strictly observed and not exceeded in any case. As a rule, the name of this type of fertilizer is made at the time of planting the seedlings. The fertilizer is applied in small doses, has trace elements, and, in general, has everything you need.
Wood ashes, or better yet – furnace ashes (or better yet – soot) – contain trace elements and up to 5% potassium, its application improves the soil structure, inhibits soil acidification, and the soil mixture is enriched, even if in small amounts, with this essential trace element necessary for the plants.
Wood ashes, or if lucky enough to get them, would be a great fall fertilizer. The nitrogen in them is minimal, we can say it is not present at all, and there is no chlorine, so it is completely safe to use these fertilizers even for young, newly planted crops. Wood ash, stove ash, and soot are best applied 150-200 grams under young plants in previously moist and loose soil, then mulched, potentially the same as your loose soil.
Interestingly, despite the small concentration, wood and stove ashes and soot contain potassium (up to 5%), phosphorus, magnesium, iron, calcium, fluorine, boron, iodine, and many trace elements necessary for the proper functioning of the plant organism, making this fertilizer very helpful in the fall.
Of course, wood ash and furnace ash (and soot) have some disadvantages. The main one is the need to have a large amount of wood ash, and if with wood ash, as a rule, there is no problem, then to get furnace ash, and even more – soot, is now almost unreal.
With this in mind, when burning tree trunks, branches left after pruning, stalks of vegetable plants, fallen leaves, and straw, there is certainly no harm in collecting ashes and using them as autumn fertilizer.
In a mature garden, it is common to add up to half a bucket of ash or soot in the fall under each tree that is more than seven years old, spreading it evenly over the root zone.
Organic fertilizer is almost the only fertilizer that can significantly increase the humus content of the soil. It also improves the exchange of air and water in the soil, prevents excessive mineralization, and naturally increases the next year’s yield, since the waking plants already have something to eat.
Obviously, fresh manure should not be used for the simple reason that it contains high levels of ammonia, which can kill the root systems of mature trees and young shrubs.
For fall applications, you can use well-prepared compost (which, by the way, can actually cover the root zone of newly planted seedlings), humus (fully and partially composted), and well-prepared manure, but diluted with 10 times more water.
Depending on the age of the tree, soil conditions, and the degree of fruiting of the plants that year, you can use about a bucket of cowpea diluted 10 times under each tree or shrub in the fall. It is best to apply the manure on previously loosened soil, or you can add it by digging the soil carefully (so as not to damage the roots).
FALL FERTILIZER APPLICATION RATES
In summary, here are the approximate fertilizer rates recommended by many farms for the most common fall fruit and berry crops.
Let’s start with pears and apples. Trees older than 8 years require up to 15-18lb (7-8kg) of humus or compost, trees older than 10 years can reach 44lb (20kg) of humus or compost, and trees older than 20 years – up to 66lb (30kg) of humus or compost. Under each tree, in diluted form, you need to make 25-30g of calcium superphosphate (embedded in the soil, as we wrote) and up to 15-20g of potassium sulfate.
Under berry trees, these raspberries, gooseberries, and currants are acceptable in the fall, make 26-30lb (12-14 kg) of compost or humus, as well as 25-30 g of calcium superphosphate, which will be spread on the borders of the root zone, and 25-30 g of potassium sulfate. Potassium sulfate can also be used dissolved in water.
Cherry and plum trees – they respond well to chicken manure diluted 15 times – 0.26 Gal (1 liter) per tree, and well-prepared manure – diluted 10 times – 0.13 Gal (0.5 liters) under each tree, all placed in previously loosened soil, 2-2.8inch (5-7 cm) from the base of the trunk. After about a week, dissolve 18-20 grams of calcium superphosphate and 10-12 grams of potassium sulfate in a bucket of water and apply the resulting solution under each plant.
WHEN SHOULD I FERTILIZE MY GARDEN IN AUTUMN?
It is best to apply fertilizer early in the fall, before the ground freezes. Fertilizer is usually applied until the third decade of December, after which no soil fertilization is done. After applying any fertilizer, it is best to make a mulch about 1 inch thick with compost. The compost and roots will protect the ground, which is not yet covered with snow, from frost when the frost comes, and in the spring, as the snow melts, it will become additional nutrients.
Don’t forget that fall is the best time for most plants to enrich the soil with nutrients; by spring, plants will begin to grow and consume the nutrients their caring owners have already put down in the soil.