Tropical plants are clueless. They do not understand that autumn is just prior to winter, when the weather may get uncomfortably cool. Philodendron selloum continues to develop fresh new leaves that mature slowly in cool autumn weather, and may consequently lack resiliency to frost in winter. Vegetable plants and flowering annuals are not so ignorant, which is why so many that were productive through summer are nearly finished, and some are ready to relinquish their space to cool season counterparts.
Like the many warm season vegetables, most of the cool season vegetables should be grown from seed sown directly into the garden. Only those that produce efficiently from fewer but substantial plants, like broccoli, cauliflower, cabbage, Brussels sprout and some of the heading lettuces, can be grown practically from seedlings purchased in cell packs. Because individual plants produce only once, more can be added to the garden in phases every two to four weeks through the season to prolong production.
Chard, kale and collard greens can likewise be grown from cell pack seedlings if only a few plants to harvest as intact heads or large leaf greens are desired. However, a package of seed costs about as much as a single cell pack of only six seedlings, but contains enough seed for many more mature heads, as well as for abundant production of ‘baby’ greens plucked from many juvenile plants through the entire season. Those to be harvested as heads should be planted in phases with enough space to mature. Those that will get plucked through the season can be sown or planted once early in the season, and perhaps followed by a second phase if productions starts to diminish.
Root vegetables, such as beet, carrot, turnip and radish, really do not recover well from transplanting from cell packs. Individual cells are sometimes crowded with too many seedlings that must push away from each other as they mature. Otherwise, if not crowded, each cell contains only a few seedlings that are not nearly as practical as simply sown seed would be.
Although each individual root vegetable plant produces only once, they all mature at different rates, so most types can be sown in only one or two phases instead of several phases every two to four weeks. If the biggest get pulled first, the smaller ones continue to mature. They are less perishable than other vegetables, so any abundance is not likely to be wasted.
There are three practical ways to grow onions. They are most popularly grown from seed or from ‘baby’ onions known as onion sets. The third and sneakier way to grow them is from separated cell pack seedlings. Cell packs typically contain too many onion seedlings that would develop into crowded clumps anyway. There are often as many seedlings as could be grown from a package of seed!
Peas get sown as seed early in autumn to grow and produce before winter gets too cold. Another phase can be sown as winter ends for spring production.