Before the plants are set in the garden, either from the hotbed or the cold-frame they should be gradually hardened to outside conditions by giving them more ventilation each day. Finally, remove the sash entirely on bright days and replace them for the night. The aim should be to produce strong, healthy plants that will make a quick start when placed in the garden.
Planting Zones
The accompanying planting tables, together with the frost-zone maps (figs. 9 and 10), are based upon records of the United States Weather Bureau covering a period of 20 years and are intended to serve as a guide for determining the earliest dates that the various garden crops may be planted in the spring; also the latest dates that it will be safe to plant certain crops and have them mature before the first killing frost in the autumn. It should be borne in mind that there is a difference of several days in the frost occurrence within each zone; this is due to differences in altitude and latitude, and also to the proximity of bodies of water and large tracts of timber.
EARLIEST PLANTING DATES
Earliest safe dates for planting vegetables in the open in the zones shown in [figure 9]
| Crop | Zone A | Zone B | Zone C | Zone D | Zone E | Zone F | Zone G | ||
|---|---|---|---|---|---|---|---|---|---|
| Bean | { | Lima | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to 15 | May 1 to 15 | May 15 to June 1 | May 15 to June 15 | ... |
| Snap | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to 30 | Apr. 1 to May 1 | May 1 to 15 | May 15 to June 1 | May 15 to June 15. | ||
| Beet | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15 | May 15 to June 1. | ||
| Brussels sprouts | do. | do. | do. | do. | do. | do. | do. | ||
| Cabbage | Jan. 1 to Feb. 1 | Jan. 15 to Feb. 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to May 15. | ||
| Carrot | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15 | May 1 to June 1. | ||
| Cauliflower | do. | do. | do. | do. | do. | do. | do. | ||
| Celery | do. | do. | do. | do. | do. | do. | do. | ||
| Chard | do. | do. | do. | do. | do. | do. | do. | ||
| Collard | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | ... | ... | ||
| Corn, sweet | Feb. 15 to Mar. 1 | Mar. 1 to 15. | Mar. 15 to Apr. 1 | Apr. 1 to May 1 | Apr. 15 to May 15 | May 1 to June 1 | May 15 to June 15. | ||
| Cucumber | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to 15 | Apr. 15 to May 1 | May 1 to June 1 | May 15 to June 15 | June 1 to 15. | ||
| Eggplant | do. | do. | do. | do. | do. | do. | ... | ||
| Kale | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15. | ||
| Kohl-rabi | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to May 1 | May 1 to 15 | May 15 to June 1. | ||
| Lettuce | { | Head | do. | do. | do. | Mar. 15 to Apr. 15 | do. | do. | do. |
| Leaf | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to May 15. | ||
| Melons | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to 15 | Apr. 15 to May 1 | May 1 to June 1 | June 1 to 15 | ... | ||
| Okra, or gumbo | Feb. 15 to Mar. 1 | Mar. 1 to Mar. 15 | Mar. 15 to 30 | do. | May 1 to 15 | May 15 to June 1 | ... | ||
| Onion sets | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 1 to May 1 | May 1 to 15. | ||
| Parsley | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to May 1 | May 1 to 15 | May 15 to June 1. | ||
| Parsnip | do. | do. | do. | do. | do. | do. | do. | ||
| Peas | { | Smooth | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to June 1. |
| Wrinkled | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to May 1 | May 1 to 15 | May 15 to June 1. | ||
| Peppers | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to 15 | Apr. 15 to May 1 | May 1 to June 1 | June 1 to 15 | ... | ||
| Potatoes | { | Irish | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to June 1. |
| Sweet | Mar. 1 to 15. | Mar. 15 to Apr. 1 | Apr. 1 to 15. | Apr. 15 to May 1 | May 1 to June 1 | June 1 to 15 | ... | ||
| Pumpkin | do. | do. | do. | do. | do. | do. | ... | ||
| Radish | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15. | ||
| Salsify | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15. | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15 | May 15 to June 1. | ||
| Spinach | do. | do. | do. | do. | do. | do. | do. | ||
| Squash | Mar. 1 to 15 | Mar. 15 to Apr. 1 | Apr. 1 to 15 | Apr. 15 to May 1 | May 1 to June 1 | June 1 to 15 | ... | ||
| Tomato | do. | do. | do. | do. | do. | May 15 to June 15 | June 1 to 15. | ||
| Turnip | Jan. 1 to Feb. 1 | Feb. 1 to 15 | Feb. 15 to Mar. 1 | Mar. 1 to 15 | Mar. 15 to Apr. 15 | Apr. 15 to May 1 | May 1 to 15. | ||
Owing to the varied character of the Rocky Mountain and Pacific coast regions, it is not practicable to present the planting information in zone form, as there may be a very great difference in the dates of killing frosts in the same general locality on account of elevation. Gardeners on the Pacific coast should be guided by the experience of competent persons in their own neighborhood. The coast region of Oregon and Washington is so influenced by ocean currents that a separate map would have to be designed to meet its requirements. Sufficient data upon which to base a map for this region are not at hand.
In zones A, B, C, and parts of zone D of the eastern United States, cabbage, turnips, spinach, kale, collards, and certain varieties of onions may be grown in the open ground throughout the winter. In certain parts of zone E spinach and kale may be grown all winter. In zone F such crops as sweet potatoes, melons, eggplants, and peppers should be planted only under the most favorable conditions, as the season is sometimes too short for their full development under adverse conditions.
Garden plants are divided into about four more or less distinct groups.
Early cabbage plants, kale, onion sets, smooth peas, Irish potatoes, and radishes may be planted two weeks before the average date of the last killing frost.
Beets, Swiss chard, carrots, lettuce, wrinkled peas, cauliflower, spinach, and sweet corn may be planted about the date of the last killing frost.