March 21st was the first day of Spring this year. I was up north and it snowed. However, down in Florida it hit the low 80's so planting is dependent on the area your story is set. Below you'll find a couple excerpts about when to plant. Most planting is done in the spring but it is amazing how many items were planted in the fall.
3655. The seasons for planting are autumn and spring; the former when the soil and situation are moderately good, and the plants large; and the latter, for bleak situations. Necessity, however, is more frequently the guide here than choice, and in extensive designs, the operation is generally performed in all moderately dry open weather from October to April inclusive. "In an extensive plantation," Sang observes, " it will hardly happen but there will be variety of soil, some parts moist and heavy, and others dry and light. The lighest parts may be planted in December or January; and the more moist, or damp parts, in February or March. It must be observed, however, that if the ground be not in a proper case for planting, the operation had better be delayed. The plants will be injured, either by being committed to the ground when it is in a sour and wet, or in a dry parched state. At a time when the soil is neither wet nor dry, the operation of planting is most successfully performed. The mould does not then adhere to the spade, nor does It run in; it divides well, and is made to intermingle with the fibres of the plants with little trouble; and in treading and setting the plant upright, the soil is not worked into mortar, which it necessarily must be, if in a wet state, evidently to the great detriment of the plants. It is therefore improper to plant on a retentive soil in the time of rain, or even perhaps for some days afterwards, or after a fall of snow, until it has for some days disappeared. Whereas, on a dry absorbent soil, it may be proper to plant in the time of gentle showers, immediately after heavy rains, or as soon as the snow is dissolved." (Plant. Kai. 157.)
3656. Pontey is a decided advocate for autumn preparation of the soil, and spring planting. "Autumn planting," he says, " is advisable only in few cases, while spring planting may properly apply to all."
3657. According to Sang, the proper time for planting the pine and fir tribes, and all evergreens, is April, or even the first fortnight in May. "Attention should be paid, that no greater number of plants be lifted from the nursury than can be conveniently planted on the same day. Damp weather is the best. When very dry, and the plants rise destitute of earth at their roots, their roots should be dipped in mud (puddle) so as to be coated over by it. In all cases, care should be taken not to shake off any adhering earth from plants at the time of planting." (Plant. KaL 341.)
Source: An Encyclopedia of Agriculture ©1825
When to plant—There is much difference of opinion as to the relative merits of fall and spring planting1 My own opinion is that fall planting is generally preferable to spring planting upon thoroughly drained soils, particularly for the hardy tree fruits, like apples, pears and plums ; and if the ground is in good condition and the stock well matured, peaches can sometimes be set in October with success1 The advantages of fall planting are several1 The trees become established during the open weather of fall and they usually make a start in spring before the ground is hard enough to allow of spring planting1 This early start not only means a better growth the first season, but,'what is more important, trees which get a very early hold upon the soil endure the drouths of midsummer much better than trees planted in spring1 Planting is nearly always better done in the settled weather and workable soil of fall than in the capricious days and in the hurry of springtime ; and the orchardist is free to begin cultivation at a time when he would otherwise be planting his trees1 Again, it is generally better to buy trees in the fall, when the stock of varieties is full and when the best trees are yet unsold : these trees must be kept until planting time, and it is about as cheap and fully as safe to plant them directly as to heel them in until spring.
Source: Hints on the planting of Orchards ©1894