Determinate vs. Indeterminate

Plant labels often say ‘determinate’ or ‘indeterminate’, but what do those words mean and how do they affect your garden harvest? Let’s find out.

Botanical definition

The botanical definitions of determinate and indeterminate tell us the science behind basic growth patterns. Indeterminate growth doesn’t stop. The main stem will just keep on growing. Think giant sequoias and other redwood trees. Indeterminate growth can also refer to sequential flowering that starts at the bottom and on the sides of a plant, and then moves in and up. Determinate growth is finite. It usually means the main stem ends with a flower or other reproductive structure. Flowering among determinate plant varieties starts from the middle and the top and moves downward and outward. So what does this have to do with your seed packet?

Genetic survival and ripe fruit

Keep in mind that all those fruits and vegetables that we love are a plant’s way of passing on genetic information. It’s survival of the species. Different plants solve the problem of genetic survival in different ways. In fact, the range of behaviors and adaptations goes beyond bizarre in some cases, but we will leave those stories for another day. Basically, in nature, some plants spread their bounty out over several weeks or even months (indeterminate), while others seem to ripen everything on the same day (determinate). In some cases, plants can switch from one to the other! Fruit trees tend to reach harvestable conditions on a determinate schedule. An overabundance of ripe fruit may attract more animals which then spread the seeds over a wider area. [I’m guessing.] Plants that spread their harvest out over a longer period of time may be improving their odds at favorable conditions for their offspring. [Still guessing.] Generally speaking, though not as a hard and fast rule, annuals lean toward the determinate side of the fence, while perennials prefer indeterminate growth. Which ever way they go, it’s a classic case of, “What works, is. What doesn’t, isn’t.” Plants that don’t reproduce successfully do not exist for long.

Human intervention

Since the Agricultural Revolution, we have been modifying plants for size, flavor, disease resistance, and time of harvest, among other things. In commercial agriculture, determinate plants are preferred because crops must be harvested by machinery, all at the same time. For the home gardener, 40 pounds of peas coming ready for harvest within the same week might not be such a good thing. [If it happens, you can always freeze or can your bounty.]

​Bushes and vines

In the garden, tomatoes, potatoes, cucumbers, strawberries, peas, and beans are just a few of the plants that can be either determinate or indeterminate. Most determinate garden plants are labeled as ‘bush’ variety, though many of them don’t actually grow into bushes. Indeterminate cucumbers, for example, will use tendrils to climb as far as they want and produce the biggest fruit they can. Determinate, or ‘bush’ cucumbers, will still spread out, but they generally stay lower to the ground and will produce a set size fruit. Indeterminate tomatoes will grow as tall as they can and continue to put out flowers throughout the growing season, whereas determinate tomatoes tend to focus their energy into bushier growth and producing their crop of tomatoes pretty much around the same time. This is helpful if you are making and canning your own tomato sauce, but it can be a problem if you prefer all of your tomatoes fresh from the garden.


Semi-determinate

Some crops, such as peas and beans, can be semi determinate. This means they tend to stop producing at a set point but can be coaxed to continue into a second or even third round of production by regularly harvesting pods as soon as they are produced. Remember, a plant is trying to pass on its genes. If they ‘believe’ they have not succeeded, they will keep trying, in most cases.

Ears: another form of determinism

Ears of corn can also be determinate or indeterminate. In this case, the variable is ear size. Ears of determinate corn will stop growing at a set size, while indeterminate corn has no set size and will reach maturity based on environmental conditions.

Pruning and determinism

Indeterminate plants can be pruned of unwanted shoots to direct growth and nutrients where you want them. Determinate plants, on the other hand, perform better if they are not pruned excessively.

Bottom line: if you want everything to come ripe around the same time, plant determinate varieties. If you prefer an ongoing harvest, plant indeterminate varieties.