Why Fall Is the Best Time to Fertilize Your Garden (& What to Use)

Are you waiting till spring comes to fertilize your land? Maybe you shouldn’t – have you thought about feeding your land in fall instead? I know, gardeners are split on the subject, and not all agree on which is the best season to make your soil fertile, but the months of October and November are gaining momentum with professionals, because there are quite a few advantages…

So, before you decide when to fertilize your land and plants, let me go through the reason why more and more farmers and gardeners choose fall over spring.

Shall I Fertilize in Fall or in Spring?

Like with everything to do with gardening, there isn’t one fixed rule for everybody, and you need to choose the best time to fertilize your soil depending on some factors:

• The climate; fall fertilization is better for cold regions, while in warmer places, we usually prefer spring (we will see why soon).
• Winter rainfalls;linked to the point above, in places where winters have lots of rain, if you fertilize in fall, lots of nutrients will be washed away, so you may have to repeat it in spring anyway.
• The type of plants;fall fertilization is better for lawns and perennials, but for annuals and fast-growing crops, spring is a better time.
• Your soil; If your soil is already fertile come fall, you may wish to fertilize it again in spring, however, in most cases, summer crops use up lots of nutrients, so a bit of feeding at this time is welcome.
• The type of fertilizer;fast-release fertilizers are wasted in fall, but you can use slow-release ones. If you use fresh manure, then, you definitely need to leave it on the soil over winter to ripen, so fall is by far the best time!

But now, let’s see why more and more gardeners are switching to fall fertilization!

Fall Fertilization Benefit 1 – Spring Is Too Busy!

The advantage that has changed many gardeners’ minds is very practical indeed. We all know what a busy time of the year spring is, and if you fertilize in fall, it will lighten your workload when the good season comes.

This way, you can concentrate on sowing and planting, and your soil will be ready to nourish your seeds and seedlings…

Fall Fertilization Benefit 2 – It Keeps the Soil Warmer in Winter

…And this is the reason why farmers and gardeners in cold countries prefer to fertilize their land in fall, before it freezes: organic matter keeps the soil warm! Yes, and it is not just that it keeps the warmth (like leaves and wood do); as it decomposes underground it produces heat, as many little bacteria are at work, as happens for your compost heap.

Soil temperature is a big issue in cold countries over winter; perennials may suffer above ground, even die back, but, as long as their roots are warm, they will survive.

Fall Fertilization Benefit 3 – Mycorrhizae

We all know that the big secret of fertile soil are mycorrhizae, those underground fungi that literally help the roots of your plants feed… But they do take time to develop, and you want to have a very thick and healthy underground “network” fully functioning by spring.

The best time to inoculate the soil with mycorrhizae spores is late summer or fall, because rains are coming and they like it humid, while in the dry season they will strive to grow…

Moreover, it takes months to see any effects after you inoculate the soil with mycorrhizae spores, at least 2, and in most cases even more. So, if you do it in spring, it’s too late!

Finally, a fertile and warm(ish) soil is also great for mycorrhizae; use the wet winter season to grow them underground, and your soil will be super fertile when spring comes.

Fall Fertilization Benefit 4 – Sturdier Plants

Plants still feed when they are dormant, and many will need to strengthen their root system over the cold season. If you fertilize their soil in fall, they will be sturdier and more resilient when the new season comes. It’s as simple as that!

Fall Fertilization Benefit 5 – Nutrient Storage

Related to what we said just now, perennials, shrubs and trees can store nutrients over winter, in their root system, and they will start more vigorously in spring if you fertilize in fall. What is more, once they grow new buds and stems as the new season comes, they will already have fertile soil to rely on.

If instead you fertilize in spring, you may miss this “jump start”, and only feed them once they have already grown new buds, stems etc.

Fall Fertilization Benefit 6 – Less Competition from Weeds

If you fertilize your plants in fall, they will be “the only ones sitting at the table”, so to speak… Or almost the only ones, because there are much fewer weeds in winter, and all the nutrients will go to your beloved perennials, shrubs and trees.

It is a better use of fertilizers!

Fall Fertilization Benefit 7 – Recovery from Summer Stress

Summer is a great and fruitful season, but also very stressful for plants: many of them fruit and flower, water is scarce and the heat can really tire them. So, it could be a good idea to give them some food at this time, to recover, and if the fertilizer you choose is organic, it will also provide moisture for their roots.

Fall Fertilization Benefit 8 – It Feeds Worms (and Other Beneficial Creatures)

Our soil is a living being, and there are many small beneficial creatures (from little bugs to bacteria) that need feeding and, why not, a bit of warmth during winter as well. They will keep the earth healthy, thriving and nutrient rich, so when your plants need lots of energy in spring, they have it!

The most iconic are worms, of course, they keep the soil loose and aerated on top of fertile (and they are necessary for lawns); so, feed them in fall, and they will work for you and your garden during the winter season!

Fall Fertilization Benefit 9 – Less Nutrient Runoff

This depends on your climate, as we said before, however, if winters are less rainy than spring (as happens in many regions), if you fertilize in the fall you will have a reduced nutrient runoff. It means that rainfalls will not wash them away from your soil as much, into rivers, aquifers, or in lakes (or even onto a road).

This can also have an environmental impact, because too much nitrogen in rivers and lakes makes algae grow too fast and too big…

And now, let’s look at the timing!

When to Fertilize Your Soil in Fall

Ideally, you should fertilize your soil before it freezes, ideally 2 to 3 weeks before the first frost, and when your perennials, shrubs and trees are going dormant. This is to keep as many nutrients in the soil but especially to avoid confusing your plants. You don’t want them to think it is spring and grow new leaves and shoots at the wrong time.

However, there is an exception; if you want to help your plants recover from summer stress, then fertilize them in early fall, but be careful not to over-fertilize them!

But what types of fertilizers can you use in fall? You must choose carefully…

Raw and Mature Manure for Fall Fertilization

In fall, you can fertilize with both raw and mature manure; let’s see how.

Raw manure is cheap, and you need to leave it on top of the soil, on the surface, for at least 3 months, so you cannot lay it in spring. You will then dig it into the soil when the good season comes.

It does have some drawbacks though; to start with, it stinks (spray vinegar on it to remove the smell); next, it is packed with urea, which can be problematic for two main reasons. It has too much nitrogen (and it can lead to imbalance) and it can be rife with pathogens. What’s more, if you place it near the stems of plants or their roots, it can burn them!

Raw manure is very common on farms, and in fact, you can virtually only use it on open fields.

Well-rotted manure, on the other hand, gives your plants a long-lasting and slow-release source of nutrients, and it is balanced. If you use it, dig it into the soil.

Compost for Fall Fertilization

Compost is the world’s favorite all-purpose slow-release fertilizer, and you can use it safely and freely in fall. But if you make your own, you will get a further advantage: with all the leaves and organic material you get in this season, you can free up space to start a new heap that will be ready in spring!

Granular Slow-Release Fertilizers for Fall

You can also use any organic slow-release fertilizers in granular form to feed your soil in fall. Unless you are growing crops, use a balanced NPK ratio, like 10-10-10. Otherwise use more specific ones for your vegetables or for your lawn.

Bone Meal to Fertilize in Fall

Bone meal is a good choice to fertilize in fall, because it boosts the roots of your plants, being phosphorus rich. However, remember that it is very powerful, so, only use a small amount.

Lots of phosphorus may sound like a good idea, but it can lead to nutrient imbalance, and what is more, if there is too much of it, it will stop the roots from absorbing zinc, iron and copper, this is called “nutrient antagonism”.

Kelp and Seaweed to Fertilize in Fall

Both kelp and seaweed fertilizers are rich in potassium, so you can use them to fertilize in fall, especially if you are growing winter crops, but there is more. They are really packed with micronutrients, which are really important for your plants’ resilience and health, and they can really help them get through winter: they are a bit like “medicines”, very much needed in the cold season!

You can use them freely on your land, and don’t worry about the salt in them; rains will wash it away. And if you don’t live by the sea and get the “real stuff”, you can still buy kelp and seaweed based fertilizers.

Wood Ash to Fertilize in Fall

Wood ash too is rich in potassium as well as many secondary and micronutrients, so it is really good for the health of your soil and plants over the winter season. Just make sure it is natural (no chemicals, paints etc…) and mix it in with compost or other fertilizers, or just scatter a thin sprinkling onto the land.

Leaf Mold to Fertilize in Fall

Leaf mold is a really excellent fertilizer, actually, it is like a “miracle cure” for your soil, and it is very abundant in fall. So, it would be a pity to waste it! If you don’t have it on your land, just go to a nearby forested area. Walk deep and find a big tree, look at the base and dig into the leaves at its feet with your hand.

When you see that the leaves are turning into compost, and there are some white filaments – that’s what you need to keep your soil super fertile over winter and ready for vigorous growth in spring!

Use Lime or Sulphur in Fall to Amend Acidity if Necessary

Summer can also cause changes in your soil’s pH; all the consumption of nutrients, the growth and heat etc., can really affect the acidity of your soil. So, fall is a good time to amend it.

If it has become too acidic, scatter some lime over your land, and if it has turned to alkaline (basic), use sulfur instead. Do check how much you need of each though, and keep on the safe side.

What Fertilizers You Should Avoid in Fall

Finally, let’s see what not to use in fall. Avoid unbalanced and fast release fertilizers, especially if you have no crops. If you use them with plants that are going dormant, you may “wake them up”.

Epsom salts too are not a good idea; very few plants flower in this season, so, unless you want to give a helping hand to your hellebores (and they don’t usually need it)… And if you do, always use a very small amount!

Finally, Wrap Up Your Land Warm!

Ok, now you know why you should fertilize in fall, and how, and with what, I will leave you with a final tip: mulch! Not only will it keep the soil warmer, but it will also preserve the nutrients within it. In the end, you don’t want to waste time and resources!