Fertilizing and Rain
Q. Can you give me some reasons that it’s not good to fertilize when it’s raining?
A. Walking on heavy soil when it is wet can compact the soil, but other than that caveat what’s wrong with taking advantage of rainfall to fertilize with organic fertilizer all the things that need it now, like roses (if you did not fertilize them in January according to the directions in my book), broccoli (after taking off the central head to keep the side sprouts growing), citrus trees (late January is the time to feed even with sythetics), cool-season lawns (fertilize with organic fertilizer now; it takes time to work) , and avocado’s (February is the month to begin fertilizing these.) What’s the difference if it’s raining?
Many times in my book I have said to fertilize just before a rain or “if rain is inadequate, water in thoroughly”. So does it not make sense that if you wake up in the morning and find it already raining and you had been planning to fertilize anyway knowing it was going to rain that afternoon that you would go out in a rain suit and fertilize even though it was raining so you would not need to irrigate afterwards? If you are an organic gardener, or even if you are not, you should have already fertilized your citrus trees in late January. If you did not do this, do it now, but what a shame you did not do it before or during the rain.
I have often fertilized in the rain while wearing a rain suit, so I wonder why you got the idea that it’s not a good idea to fertilize when it’s raining? That sounds like the advice of someone other than me. It also sounds like advice I heard from a weather man on one of the news channels. Several weather men give garden advice and goodness knows where they get some of their information. They often say things that are not true or incomplete and thus misleading. When I heard a weather man saying “Don’t fertilize now because there is too much rain.” I wished I could pop up onto the screen and say “Hey wait a minute! That is not entirely correct!” The only really negative aspect of fertilizing with ORGANIC fertilizer in the rain is that the fertilizer gets wet and so do you and some of the fertilizer inevitably gets on your clothes and might ruin your rain suit. (I keep an old one for this purpose.)
Now if one is talking about SYNTHETIC nitrogen fertilizers—that is, manmade fertilizers— that may be a different matter ( though this does not apply, as explained above, to citrus, avocado, and those veggies that need fertilizing now.) Synthetic fertilizers such as sulfate of ammonia and urea, are completely soluble, thus fertilizing when we have very heavy rains will wash them into the ground and perhaps even right through the root zone and down into ground water too rapidly. This is why March is usually considered to be the classic month for fertilizing the basic landscape when using synthetic commercial fertilizers. But I am not espousing any of these synthetic, man-made fertilizers.
I recommend organic fertilizers, and these should be applied early since they take time to work. (Consult my book for some of the products and homemade concoctions you could be using (and see the chart of generic organic fertilizers on this website.) Organic fertilizers must be in contact with the soil in order to become activated and then they become an integral part of the soil and continue working in the ground. All this process takes time. For example, gardeners who add a mulch of horse manure in fall ahead of the rain are allowing time for the manure to age on top of the ground as well as allowing the winter rains to wash the nutrients into the ground. This process will greatly improve garden soil with great benefit to garden plants. Heavy rains are a benefit to the manuring process since they will wash away any salts. (Do not mulch succulents or California native plants with manure.) Additionally, partially rotted organic matter actually works with the soil as it rots further in the ground. The wondrous fact is that as it decomposes and becomes humus it creates nitrogen in the process and releases it to plant roots, but it needs moisture for this to happen. So these heavy rains we are having will only help the process. Get out there and take advantage of the rains instead of waiting until later and then needing to waste our precious irrigation water to do the job that could have been done by rain.