In commercial fruit farming it is important to pick very close to the optimum date (within a day or two). This date is naturally different for each variety, and within a variety the date varies according to the locality and whether the fruit is destined for short-term or long-term storage (if the latter, it is picked relatively early so that it has more ripening to do in store).

The optimum pick date has to be known in advance to assist in planning, and is determined mainly by monitoring three maturity traits: soluble solids content, starch content and firmness. As the fruit ripen the soluble solids content (largely sugars) goes up as the starch content goes down, and firmness also decreases.

In the amateur context these three traits cannot be estimated very easily, except perhaps subjectively in cherries, plums and early-season apples, which are picked at full ripeness and eaten very soon after picking.

In all tree fruits, the following observations help in judging ripeness:

 (i) Windfalls. Some fall of fruit signifies the approach of full ripeness.

(ii) The parting of the fruit from the tree. When ripe, a gentle lifting of the fruit, hence a bending back of the stalk, will cause the fruit to part easily at the base of the stalk.

(iii) Colour, specifically background (non-flush) colour in apples and pears. This background colour tends to turn from dark green towards a paler green, green-yellow or yellow, depending on the variety.

 Late-season apples reach a stage at which they part from the tree easily but are not necessarily good to eat at that time. For example, in Kent, ‘Golden Delicious’ can ripen fully on the tree (but may take until early November to do so), whereas more strongly flavoured apple varieties like ‘Ashmead’s Kernel’ have a brash quality at picking and need to mellow in store before they're palatable. Pears are still very firm at picking and need to soften in store.

 In relation to the ripeness of fruit, amateurs and small-scale growers have four advantages over commercial growers (assuming that they have less anxiety over labour costs).

 1. Instead of picking just once, at an optimum date, fruit trees can be picked over lightly more than once. Since the fruits on one tree do not ripen all at exactly the same time, one optimum date implies some waste and loss of quality: some have already fallen and in the case of stone fruit some are rotted, while others are not yet fully ripe. Repeated picking reduces waste and allows as much as possible of the crop to be picked at its best.

 2. Some varieties such as early-season plums and early-season apples are best eaten within a day or two of picking (some are best on the same day), which means that they are likely to be past their best if not home-grown, given that the necessary commercial operations of grading and distribution generally take at least several days.

3. On commercial fruit farms any variation in ripeness between individual fruits is clearly undesirable, and is minimized by making the growing conditions as uniform as possible. The small-scale context tends to be more variable, but here the variation it is not necessarily a disadvantage and may even be an advantage. By even-ing out the harvest, a glut might be avoided and tree-ripe fruit is available from any one tree for up to several weeks.

4. Home storage of late-season apples allows the fruit to ripen in a relatively natural way, achieving a certain full-ripe character that apples stored in commercial controlled-atmosphere stores do not have.

In conclusion, the question ‘when is my fruit ripe?’ is not always simple or straightforward. The optimum harvest date varies from year to year and frequent observation is necessary to decide when to harvest. A lack of attention will result in a lot of fallen fruit causing waste, nuisance and poor hygiene, and such fruit as is harvested may be past its best or unfit for storage.