What does all this rain mean for the landscape? In most cases, it means growth is lush this spring (weeds included). You should be cutting your lawn about every five days to keep up with the growth. One of the best things you can do for your lawn is to follow the rule of one-third, which means remove only one-third of the leaf tissue with every cut. That allows the grass to photosynthesize in the remaining leaf tissue and make sugars for healthy root growth. When you remove more than one-third of the leaf tissue with each cut, you stress the grass. In addition, clippings tend to clump up so they are unsightly and exclude light from reaching the grass below the clump. Most people cut their grass once a week, so every 5 days means changing your routine while growth conditions are so favorable.
Weeds are growing too and I have seen some of the largest dandelions ever this spring. You can hand pull weeds, but be sure to get the entire root system. When you pull up a weed, you disturb the soil and bring up additional weed seeds. One school of thought recommends spot spraying weeds with herbicides instead of hand pulling to control the weed, but keep the weed seeds buried so they are not exposed to light and allowed to germinate. If you put a preemergent crabgrass herbicide on your lawn this spring, you might need to make another application. Crabgrass preventers work by setting up an herbicide barrier in the soil. When crabgrass seeds germinate, the young sprout hits the barrier and dies so the crabgrass never actually emerges from the soil. That barrier can be washed away with lots of rain and that has probably happened this spring.
One problem with lots of rain is prevalence of fungal diseases. Fungi spread when there is a film of water on the leaves. Most disease control must be preventative, so once you see a disease it is too late for treatment. In most cases, dry weather and good air circulation will clear up a disease outbreak in the landscape. Hand picking spent flowers or pruning out diseased foliage is usually a good idea and reduced disease spread.
Lots of moisture is good for some vegetables and not so good for others. Peppers like hot, sunny weather, so pepper plants might be looking a little sorry after the rain we have had this spring. As soon as temperatures get solidly hot and we get a dry spell, their growth should take off. Most of the vegetable garden should be responding well to all the moisture. Be sure to add fertilizer as plants grow rapidly, they will use the fertilizer you applied at planting and start depleting the soil.
If you have done a lot of new planting this spring, the wet weather has been great for your landscape. Think of all the time you would have wasted watering newly planted trees, shrubs and perennials. Mother Nature took care of that for you. However, remember, plants are not fully established for several months to a year, depending on their size at planting. When we hit our inevitable dry spell, check your newly planted specimens to make sure they are not drying out. They may require supplemental watering at that point.
Poorly drained landscape sites may be waterlogged this spring. A surprising symptom of waterlogged plants is wilted foliage. You see the wilted leaves and think they must be dry, so you add water. In fact, the plant is wilting because the wet conditions have rotted enough of the roots to prevent water uptake even though there is plenty of water in the soil. Inventory your landscape looking for plants that are suffering and consider replacing them with a more water tolerant plant. Buttonbush (Cephalanthus occidentalis) is the most moisture tolerant shrub I have seen. This brochure from Delaware Cooperative Extension recommends plants for a rain garden that tolerate moisture (http://s3.amazonaws.com/udextension/lawngarden/files/2012/06/live_eco_final.pdf).