Many of them take all summer for their produce to mature, and a two-week delay may mean there is nothing harvestable. The trick is to find edibles that produce vegetables like annuals produce flowers, in other words, all summer long. Squash and cukes are two prime examples. If you can't find any at the nursery, ask friends and co-workers if they have any in pots that they did not have the room to transplant but can't bear to throw away. Pinch off any blossoms, feed, water and transplant.
Tomatoes are a riskier proposition.
Outdoor varieties are determinates, which means the fruit ripen all at once and usually late in the season. Even when I start plants on time, late August often finds me with bushels of green tomatoes. On the other hand, if you are willing to provide frost protection during early fall frosts and don't mind letting an unripe crop turn colors indoors, give it a try. If the worst happens, your plot's bald spots will be filled with foliage and you'll be able to survive on fried green tomatoes until Thanksgiving. If you are one of those amazing persons who do not care for tomatoes, this is a time when you are actually more fortunate than those who do like a bit of red in their salads.