There's no shortage of heat lamps, smart pots, and plant food you can buy to compensate for your lack of a green thumb. Home gardening can be expensive, but it doesn't have to be. One of the best sources of nutrients for your plants is something most people pour down the drain.

According to SFGate, watering your plants with reserved cooking liquid is an easy way to boost their nutrient intake. The water used to boil eggs and vegetables is richer in minerals than plain tap water. The phosphorus, nitrogen, and calcium in leftover cooking water act as fertilizer for plants, allowing them to grow at a steady rate. The bonus nutrients also help soil retain moisture, which means you can water your plants less often in addition to giving them less plant food. It's a good idea to let the cooking water cool to room temperature before administering it to your greenery.

Not all cooking water is suitable for your plants. A recipe may tell you to heavily salt the pot, but water that's as "salty as the sea" can be poisonous to plants. If you're committed to reusing your boiled water, you may have to put up with bland vegetables (or veggies that are seasoned after they're drained).

Water used to cook standard supermarket vegetables also poses a threat. Vegetables sprayed with pesticides can leach those chemicals into the cooking liquid, turning it into a dangerous cocktail for your plants. You can avoid this by only reserving water that was used to cook organic produce.

Many of the perils plant parents face can be solved with resources they have at home. If you're less concerned with the quality of your plant water than the quantity, a coffee filter can help. Paper filters lining flower pots will absorb excess water, making the plants harder to kill. Here are more tips for keeping your plants healthy.

[h/t SFGate]