Feed Your Potted Plants
and They will Thank You with Their Beauty

If plants make their own food, why fertilize?

Plants make their own food through photosynthesis -- which is why they need sunlight, air and water in order to thrive.

But without nutrients that serve as "building blocks" for their energy, plants won't have any raw materials to work with. Plants that grow out in open soil harness the nutrients dissolved in the soil, taking them up through their roots and up to their leaves. Nutrients in open soil or in the wild are usually naturally replenished by decaying organic matter.

Potted plants, on the other hand, don't have the benefit of this natural process of nutrient replenishment. Which is why they need your help in providing them nutrients after they've depleted what is in their pots. Without your periodic application of fertilizers, potted plants become weak, sickly and may even die when they can no longer produce food.   Back to top

How do I fertilize flowering and decorative foliage plants?

Practically all commercially bought potted plants were raised in nurseries where they were kept on an exclusive diet of synthetic or chemical fertilizers that were always given in regular doses. Which is why if, after buying them you neglect to fertilize them for several weeks, they go through a period of withdrawal.

Continuing their fertilizing regimen is the best way to sustain their healthy growth. (However, if your plants were raised in nurseries in the highlands such as Baguio or Tagaytay, they could suffer due to the sudden change in temperature or elevation. Roses and hydrangeas, for instance, grow beautifully in these colder regions but could never produce blooms of the same size in the hot lowlands. But they can thrive, still producing blooms but of a much smaller size. Many growers don't reveal the real location of their nurseries so as not to discourage buyers from Metro Manila, but take heart. It's still possible to keep these plants happy in the lowlands given the right care and environment.)

If you want to continue with the use of chemical fertilizers, choose between the liquid kind or crystalline types that you mix with water. You then spray the solution on the leaves or pour over the plant and potting mix. Be sure to follow the directions on the package.

There are also granular fertilizers (locally referred to simply as "complete" which look like polvoron pellets the size of big monggo beans). For plants grown for their leaves instead of their flowers, urea (which looks like miniature moth balls) is also sometimes recommended by plant sellers. However, both of these are not good choices for container-grown plants because of their high risk of burning the plants. Also, very little of the nutrients they contain are actually taken up the plants as most of it is lost to leaching or evaporation. But if this is the option you prefer (because it is the cheapest), wet the potting mix first to lessen the chance of burning. Then apply just a pinch of the granular fertilizer not too close to the plant base then water again.

Or you can opt to fertilize the 'low maintenance' way. Or shift to organic fertilizing.

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What are slow-release fertilizers?

Also called time-release or controlled-release, slow-release fertilizers look like little translucent balls of 'sago' and have plastic materials that coat the fertilizer. Water enters the coating and slowly releases nutrients over time. The nutrient release is also determined by temperature.

If you repot your plants into Plantastic RED EARTH Soil-less Potting Mix, you need not fertilize for four months if you keep the pots outdoors and even upwards of nine months to a year for plants grown indoors. After that period, replenish the nutrients with a fresh dose of slow-release fertilizers. Or apply compost every month.

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How do I fertilize herbs, vegetables and fruit trees grown in pots?

The best and recommended way to fertilize all plants -- particularly edible plants -- is organically. Organically-grown herbs, fruits and vegetables are much more disease- and pest-resistant; and once harvested are more flavorful, aromatic and nutritious.

Topdress pots with compost every two weeks to two months, depending on pot size, plant needs and growing conditions. You can buy compost from garden shops or make your own compost from kitchen waste right at home.

Supplement this with weekly applications of liquid organic fertilizers that you spray on leaves. You can use foliar fertilizers made from seaweed or fish emulsion. Manure tea is not advisable for use on edible plants but they are perfectly fine if you are fertilizing ornamentals.

Organic fertilizers provide all the basic nutrients the synthetic fertilizers do, plus a wealth of micronutrients, organic compounds and hormones that synthetic fertilizers don't provide. Their only disadvantage would be their smell -- but this quickly dissipates after an hour or so.

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What is a Foliar Fertilizer?

This is a fertilizer that is particularly meant to be sprayed on the leaves. Most trace elements are found to be delivered best when applied to the leaves. Foliar feeding is also a more rapid way of getting nutrients into a plant if you need to give it a quick boost.

Foliar fertilizers are best applied in a fine mist early in the day - so the sun doesn't just evaporate the fertilizer instantly with its heat.

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How often should I fertilize?

In hot areas of the country, it's best to fertilize your potted plants with foliar feed weekly. And topdress your potting mix with compost every two weeks to two months, depending on the plant, the season and the temperature.

If you are using slow-release fertilizers, replenish every three to nine months -- depending on the plant and its location -- by lightly scratching some into the top inch or two of the potting mix.

Is it possible to over-fertilize?

Yes, it is. It’s important to follow recommended fertilizer application in terms of frequency, quantity and delivery. Some fertilizers are meant to be sprayed on leaves, whereas others are not supposed to come in contact with plant parts. Be careful not to overfeed. It’s better to underfeed than to over-fertilize; the latter can be harmful, and even fatal to plants.

Signs of over-fertilization are yellowing (though this may also be due to over-watering), deformed or burned leaves. In case of over-fertilization, flush the pot with water – meaning, let the water flow through the potting medium to wash the extra nutrients away.

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