QUESTION: Can I use last year’s compost?
ANSWER: Yes, you can reuse last year’s compost if you take the time to amend it in order to replace lost nutrients and improve deteriorating soil structure. Old compost can be rejuvenated using worm compost, homemade compost, bokashi compost, manure, green waste compost, store bought compost, chicken manure pellets, general purpose organic fertilizer, biochar, and rock dust.
You don’t need to add all of these ingredients of course, but one or two of these can rejuvenate your last year’s compost into an excellent growing medium for another year worth of cultivation. Select the ingredients you are going to use to amend your compost from last year based on what you have access to in your area.
Some crops will grow better in refurbished compost than others. Most low to medium feeder crops will do just fine in old compost but some heavy feeders will have reduced output and should be grown in fresh compost and soil whenever possible.
Leafy vegetables such as salad greens, lettuces, chard, rocket, and kale are perfect for growing in rejuvenated compost. Beans and peas, most root vegetables and herbs, as well as squash and zucchini also tend to do well in revamped compost. Heavy feeders like tomatoes, aubergines, chilies, peppers, and strawberries will grow in old rejuvenated compost, but will likely only produce weak yields.
If you are planning on continuing to rejuvenate old compost for multiple years of use, you may want to consider starting your own composting system, vermicomposting system (worm compost) or bokashi composting system at home. It may seem like a lot of work, but it’s a great way to reduce your waste and recycle your kitchen, lawn, and paper scraps into nutrient rich garden soil, which can save you a lot of money too.