Vegetables: It is usually safe to put tomato and pepper transplants out after May 15 in the Madison area, but outlying more rural areas such as Blue Mounds, Oregon, etc. may not be warm enough yet. Air temperatures should go no lower than 55 degrees, especially overnight, and soil temperatures are best at least in the 50s or higher. Even in Madison it is definitely possible to get a frost or freeze after the 15th, so do watch the weather predictions carefully and be prepared to cover sensitive plants if temperatures are going to be in the low 40s or lower.
Don’t plant out (or sow seed for) basil, melons, squash, cucumbers or okra until the first week of June as they are all very cold-sensitive both to soil temperatures as well as air temperatures.
Lawns: Fertilize lawns around Memorial Day. At this time, the root and shoot growth are both at optimal stages to use fertilizer. Don’t apply more than one pound of nitrogen per 1,000 square feet per application to grass growing in the sun or more than ½ lb of nitrogen per 1,000 square feet per application to grass growing in shade. Use a product that has at least 25-50% of the nitrogen in a slow-release form for even feeding over several months. It will say this on the package. It may be referred to as insoluble nitrogen. If you only want to fertilize once a year, (which is a very conservative fertilization program) the most important fertilization time is around Labor Day.
Visit http://learningstore.uwex.edu/ and enter A2303 in the search box for a publication on lawn fertilization.
If you are interested in using organic fertilizers on your lawn, another publication at the Learning Store is A3958, “Organic and Reduced Risk Lawn Care.” It addresses preparing an organic or low-input lawn as well as organic fertilizers, watering, and organic or lower-risk weed control products. Keep in mind that organic products will release the nitrogen and other nutrients more slowly and they are less concentrated than traditional products, so you will need to apply at a higher rate and/or more often to achieve the same results.
You may also want to check out “Do-it-Yourself Alternative Lawn Care,” publication A3964. You can view and print these yourself; you don’t have to purchase them, although they can be purchased through the Dane County UW-Extension office. Scroll down to the gold box marked “View publication” to view or print at your home computer.
Master gardener plant sale: If you are out and about on May 19, stop by the UW-Extension Dane County office (5201 Fen Oak Drive on the East Side of Madison) for the annual master gardener volunteer plant sale. The sale runs from 11 a.m. to 3 p.m. Hundreds of plants including vegetables, annuals and perennials will be offered for sale. Cash or check only.
There will be a Ask-A-Master-Gardener booth at the event where you can get answers to gardening questions. Proceeds are used to support the Teaching Garden surrounding the building and to support educational programs at schools, community gardens, and other venues. Arrive promptly for the best selection.
Visit http://dane.uwex.edu/horticulture/teaching-garden/ to learn more about the garden, and to see photos and information about the shrubs, trees, and perennials in the Teaching Garden. Each of the plants in the garden (other than annuals and some vegetables) has a label sign with a QR code that viewers with a smartphone can use to access the blog that has information about the plant including cultural needs, flowering time and other information.
The rain date is May 26 — we only call the sale off if there is a serious downpour with lightning and/or high winds. I hope to see you there!