Organic Growing Techniques

Organic Liquid Feeds — How To Get The Best From Them

Sometimes your plants need a nutritional boost but you don't want to resort to the 'quick fix' of mineral-based fertilizers. If this is the case, look no further than the next best thing in the organic world. Organic liquid feeds are a quick and easy way to replenish tired potting mixes so that your organic plants can keep producing for longer.

General Organics BioThrive Organic Liquid Feed

How do you grow a ten foot tomato plant in a three gallon pot—and keep it producing delicious fruit all summer long? The answer is simpler than you might think—and, for many gardeners, it starts with organic liquid feeds. 

It’s easy to see why growing a large, hungry plant in a small container places extra demands on your potting mix. Everything your plant needs, both in terms of moisture and nourishment, must come from a relatively low volume of growing media. Even premium organic potting mixes loaded up with goodies such as bone meal, Alaskan humus, worm castings, alfalfa meal, and bat guano will eventually run out of steam and become nutritionally exhausted, especially when used to support heavy-feeding plants over a long growing season.

Young tomato plants just established in Smart Pots - breathable fabric aeration containersOrganic liquid feeds are an easy and natural way of replenishing the nutrient content of your potting mix—but they do a lot more than simply adding organic matter and nutrition. Organic liquid feeds also provide an essential source of food for countless micro-organisms living in the potting mix. These micro-organisms (primarily bacteria, fungi, protozoa and nematodes) may be very small but they do incredibly important work. Their combined effect is to convert organic matter into plant-accessible food, as well as transporting and storing it so that it doesn’t simply get washed away when you water.

Tomatoes making their way up a trellis - their lush, green growth is powered in part by liquid organic feeds.At this point, it’s worth noting a key difference between organic liquid feeds and mineral-based fertilizers. Organic growing methods require the presence of a rich diversity of microscopic life in the soil itself whereas mineral-based fertilizers are designed to provide your plants with food in a directly accessible “ionic” form—with no need for microorganisms.

Three healthy tomato plants at around twelve weeks old grown in 5 gallon Smart Pots

All organic inputs (whether in liquid or solid form) first need to be broken down within the potting mix by micro-organisms so they are usable by the plant. Why? Well, scientists believe that bacteria and fungi pre-date plants by over a billion years in our planet’s evolutionary development. In other words, plants exist because bacteria and fungi existed first.

Quality organic potting mix most likely already contains some of this microscopic life already—but to really make it work for you, try brewing your own compost tea, a ready source of live micro-organisms for your plants.

Tomato leaves showing nutrient deficiencies - can you spot what's lacking here?

When applying organic liquid feeds, use a measuring syringe or a cup to accurately dose the required amount of feed into your watering can. Be sure to always read the label. Most organic liquid feeds can be used with every watering, but don’t take your eyes off your plants! If you see an overall paling of foliage, this is a fairly good sign that your plants have outgrown their dosage and are hungry for more feed. Try stepping things up by 20% and observe your plants over the next week or so.

Over-fed tomato growth tip showing signs of over-fertilization - note the blueish tinge to the foliage

Be careful also not to over-feed your plants. If you begin to notice your plants’ foliage turning dark green with an almost blueish tinge, this is a sure sign you’re providing more feed than is necessary. Signs of prolonged over-feeding also include discoloration of leaf tips and leaf margins and, in extreme cases, curling downwards like claws. If you see any of these signs, temporarily suspend use of the feed and irrigate with plain water for a week or so instead.

Botanicare Pure Blend Pro Grow Organic Liquid Feed

Finally, large plants grown in small containers require regular waterings, as much as once or more per day in warm weather. Breatheable, fabric pots help to regulate root zone temperature and keep plant roots well aerated. They also guard against root circling and mitigate the risks associated with over-watering.