How to Fertilize House Plants

Indoor plants are among the best things to grow and enhance your home’s decor and to help clear the air.

Many indoor gardeners know all about lighting and watering for their plants, yet one area often overlooked is that of feeding them fertilizer.

The conditions to grow indoor plants are very different than those outdoors, so you need to make sure not to overdo the feed. Get it right and your plants can last for years.

House plants on top of table

Using this guide, you can learn how fertilizing house plants aren’t too hard, and you will understand which is the best fertilizer for indoor plants. You can also find how to care well for their feeding requirements.

What is the Best Fertilizer for Indoor Plants?

Rather than finding which may be the best fertilizer for indoor plants right off, it is better to understand the type of fertilizer first for fertilizing indoor plants. (Find the Best Soil Test Kit)

Once you know this, you will know which type you need and how to use it to grow healthy, beautiful plants.

Unlike outdoors, houseplants are limited to the size of the pot and the amount of soil inside it. Outdoors, plants can send out roots in search of easy to find nutrients and food. In a pot, a plant can’t send roots out very much to search for food.

Fertilizer accompanies your potting soil. When potting soil products are new, plants don’t require any other feed. New mixes come fortified with nutrients and vitamins.

Inside a good couple of months, you may find your houseplant has consumed many of the nutrients from the soil. For continued healthy growth, you’ll find plants need fertilizer during the growing season. (Read Add Phosphorus To Soil)

Be careful feeding houseplants as too much fertilizer is worse than not enough. You can scorch leaves, or even worse; you can kill them.

Organic products are best as there are concerns over the environment when synthetic fertilizers find their way into the water system.

Fertilizer Types

Fertilizers arrive in several forms: liquid, stick, tablets, granules, and slow-release.

Liquids and the slow-release products are the best two suited to indoor use.

Sticks and granules look easy and great, yet don’t disperse nutrients effectively. Granular fertilizers are made for outdoor use.

Organic fertilizer is also good for fertilizing houseplants and are increasing in popularity. You find these in liquid forms and also dry. Either type can provide all that actively growing plants require in the growing season.

Liquid Fertilizer

Liquid fertilizers are dissolved in water before application.

Depending on label instructions, you can fertilize every time you water or in between during the growing season.

Plant types also affect the frequency, as some that have large blooms may need more frequent feeding.

You can control this, such as when you cease feeding in winter or increase feeding as the plant has new growth.

Slow-Release Fertilizers

Many gardeners and experienced growers, for indoor and outdoor plants, are turning to slow-release fertilizers.

Such fertilizers are coated and which slowly leaches nutrients into the soil. Individual pellets come with different thickness of coatings, which dissolve at different speeds.

A single application can last three to nine months. The only downside will be higher costs for slow-release fertilizer, although this cost balances out through fewer purchases.

Granular Fertilizer

Dry pellets of pure fertilizer can be hand-mixed into potting soil. However, these tend to be used more outdoors and can be hard to control inside pots for houseplants.

Granular fertilizer releases its nutrients in one go as the soil is watered. Because of this, there is no control.

Buying Fertilizer

All general-purpose fertilizers will provide the necessary macronutrients houseplants require, including nitrogen, phosphorus, and potassium.

  • Nitrogen promotes healthy development.
  • Phosphorous encourages healthier blooming and leaves.
  • Potassium stimulates strong root growth.

You can get specialty type of fertilizer for plants like African violets. Such fertilizer delivers optimized amounts of nutrients for that unique plant type.

When Should I Fertilize My Indoor Plants?

Houseplant Spring Fertilizing Schedule

Begin fertilizing houseplants around 8 weeks before the final spring frost is expected.

Some areas can be the middle of May, so fertilizing starts in mid-March. At the same time, days get longer and houseplants to move from semi-dormant states into periods of active growth.

The first indoor plant fertilizer applications need to be at half strength.

Zoom in shot of a house plant

If using liquid houseplant fertilizer, mix to half strength. Feed your plant when they’re starting to get ready for active growth, and not ready for a full shot of nutrients to fuel their prolific growth.

Summer Fertilization Schedule

As summer arrives, move to a more regular houseplant fertilizer schedule.

Liquid fertilizers will be applied more frequently, such as bi-weekly or monthly. Indoor environment and plant types will dictate this.

Granular products are used less frequently, perhaps once every month or so.

Slow-release houseplant fertilizers break down slowly and release nutrients over longer periods. One application of these fertilizer products will last three to four months.

Liquid organic fertilizer is a fantastic choice as it’s made from natural ingredients. Worm casings one example, you can even use two in conjunction without too much impact.

Houseplants are in active growth states when summer light is high, and they face constant temperatures indoors, or you move them on your patio, and the temperatures fluctuate.

Fall Fertilization Schedule

Around eight weeks before the first expected fall frost, start to ease off houseplant fertilizer in both frequency and the amount. Starting mid-August can be the right time to cut fertilizer by half and extending the time in between fertilizing to cover up to 4 feedings. You should then be in winter.

Winter Fertilization Schedule

Houseplants won’t have any active growth in the winter so you can cease feeding. If you do, you could cause fertilizer burn and brown leaf tips on your plants.

Fertilizing Exceptions

If you live in a part of the USA that doesn’t receive regular frosts, you can fertilize your houseplants all winter, yet these will need to be half strength and at the frequency of a summer schedule. Light levels more than temperatures will dictate this.

If you live in a tropical environment, and it’s warm all the time, you can maintain a summer fertilization schedule around the year.

Read more: Best Pruning Shears

How To Fertilize House Plants

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