Why don’t we grow strawberries from seed?

Figure 1. Bareroot strawberry transplant straight from the box and ready to plant. (this and all subsequent photos by G. J. Holmes)

Virtually all strawberry plants grown to produce fruit were planted as a transplant. Transplants take on many forms, but in California we use bareroot transplants (Fig. 1).

Why not use seeds instead? Those little things on the outside of every strawberry fruit are seeds encased in a hard outer coating (Fig. 2.). They are technically “achenes” but “seeds” will do for now.

If you plant seeds from a strawberry fruit, some of them will germinate, but very slowly. Under optimum conditions it takes about three weeks for the seed to germinate. The seedling that emerges is a tiny plant (Fig. 3). It takes another week to see the first true leaves (Fig. 4) and you’re still looking at a very tiny plant that is months away from producing a flower.

Figure 2. A. The “seeds” on the surface of strawberries are called “achenes” because the seed is enclosed in an outer shell. The thin, curved structure at the left side of each achene is the dried up pistil. B. Strawberry achene size (2-3 mm) compared to the tip of a ball point pen (upper right) and cross section (lower left) showing the seed encased in the outer coat or pericarp. C. Strawberry seedlings grown from seed showing first true leaves 2.5 months after planting.
Figure 3. Recently germinated strawberry seed showing the seed coat still attached to the cotyledon, 20 days after planting. A 0.5 mm mechanical pencil is shown for size reference.

Contrast that to the bareroot transplant, which will push out a new set of leaves immediately after planting (Fig. 4) and produce flowers within days. A flower will take about five weeks to develop into a ripe fruit.

So time is a big factor. If you planted seeds, it would take a year to get a decent sized plant that could produce fruit. That’s too long. The transplant will do it in 2-3 months.

Size is another factor. How would you plant that tiny seed and nurse it to maturity in a field setting? Tiny strawberry seeds and seedlings have to be babied along until they are large and robust enough to survive outdoor conditions.

Figure 4. Newly emerged leaves one week after planting a bareroot transplant.

When we grew our first crop of strawberries at Cal Poly, I wondered why we didn’t see volunteer strawberries in that field when we grew a subsequent crop. After all, thousands of fruit that didn’t get picked ended up rotting and the seeds ended up in the soil. Wouldn’t these all germinate and give rise to a lawn of tiny strawberry plants once the field was irrigated again? That’s what happens if you let weeds or any other crop go to seed the previous season. With strawberries, most of the seeds don’t end up in an environment where they can survive the journey from seed to mature plant, but if you look closely enough you will find volunteer strawberry plants, just not very many.

And lastly is the genetics piece. Bareroot transplants are actually daughter plants that are clones (genetically identical) of the mother plant. Seeds are produced by the exchange of genetic information from two parents. And since strawberries are a hybrid (Fragaria x ananassa) you’re going to get a lot of variation in the progeny or offspring. We don’t want that variation because a lot of it will turn out to be inferior in some way. The beauty of clonally propagated plants is that once you have the traits you desire most, the daughter plants will all have the same traits and this leads to higher and more uniform productivity.

And that’s why we don’t farm strawberries by starting with seeds. On the other hand, strawberry breeders work with seeds because they are deliberately crossing specific parents to produce progeny that have specific, desirable traits. In order to get new individuals with unique traits, you have to introduce new genes from new parents.