5 Secret DIY Plant Food Solutions

1. Try Matchbooks as Fertilizer

Matchbooks as fertilizer? Yes! But only when you want to add sulfur to the soil to lower the pH for acid-loving plants. Tear out the matches from several matchbooks and toss them into the bottom of planting holes for impatiens, hydrangeas, azaleas, and gardenias.

2. Turn Your Fireplace into Fertilizer

Hardwood ashes from your fireplace will supply potassium and phosphorous to garden plants. Just make sure not to use wood that has been treated with preservatives or anything else. To fertilize plants, spread a half-inch layer of ashes a few inches from the stem and dig it into the soil.
A couple of caveats:
1) If you store ashes outside, protect them from the rain or their nutrients will be depleted;
2) don't use ashes around potatoes, since ash can promote potato scab.

3. Limit Your Plant's Coffee Consumption

It isn't the caffeine in coffee grounds that garden plants like azaleas and rosebushes and evergreens love but rather the acidity and aeration the grounds provide — not to mention nitrogen, phosphorous, and trace minerals. Just be sure to dig the grounds into the soil to keep them from becoming moldy.
How much to use? Dig about ¾ cup of grounds into the soil near the roots, repeating once a month. And don't overdo it. Fertilizing even acid-loving plants with coffee grounds too frequently could increase soil acidity to undesirable levels.

4. Add Sawdust and Leaves to Aging Manure

Fresh, or raw, manure must be aged so that it won't burn your plants' roots — and only the most committed home gardeners will wait for the six months it takes. If you're one of those gardeners, water a fresh manure pile, cover it with a tarp so the nutrients won't leach out during a rain, and turn the pile with a pitchfork every 10 days or so. To control the odour (especially in summer), add sawdust, dead leaves, or wood chips, forking them evenly into the pile.

5. Try a Drill for Tree-Feeding

To make sure fertilizer reaches a tree's feeder roots, put your power drill to work on something besides wood: the soil. Use a bit at least 1 foot long and 1½ inches in diameter, and bore holes in the soil around the drip line — the imaginary circle beneath the outermost tips of the tree canopy. Space the holes about 2 feet apart, then bore a second ring of holes about 2½ feet from the tree trunk. Funnel a slow-release fertilizer into all of the holes, and then plug them with soil and water well.

Information provided by: Reader's Digest Canada
For more tips and tricks visit their website at: http://www.readersdigest.ca/