Blooms are a hallmark of the summer garden, but when it comes to our edible gardens, the nuances of flowering can help us sort out certain problems and maximize productivity. This week's gardening feature runs through some popular crops, with insights into how the flowers can guide our gardening practice.
Once summer heat arrives annual herbs start to flower, often at the expense of leaf production. To maximize leafy growth, cut back about one-third of the plant (including flowering stems); pinching the just flowering tops will lead to rapid regrowth of the flowers... but not more leaves. Herbs such as cilantro and arugula will never become leafy again once they start blooming, and should be allowed to finish flowering (for seed harvest) or be culled and succession planted.
Perennial herbs are not negatively impacted by flowering, and in fact, many perennial herbs have peak flavour when in bloom. Oregano, thyme, catnip, lavender and most perennial medicinal herbs are much stronger when harvested in bloom.
This year's unusual phenomenon has been the occasional flower occurring on normally non-flowering Aussie Sweetie and Pesto Perpetuo basils, most likely related to the persistent hot weather this summer. Curious gardeners may allow these to flower to maturity and see if seeds develop (normally these can only be grown from cuttings so seeds would be cool, although they are likely sterile). As far as I can tell, the flowering is so minimal that it is not impacting the leafy growth of either Aussie Sweetie or Pesto Perpetuo, so I am going to see what happens!
One reason to leave regular basil in flower is that bees LOVE it! The purple flowering types are also very attractive in the garden or as cut flowers.
If you are a seed collector, it may be worth leaving a few basil plants for the bees to enjoy... ultimately rewarding you with next year's seed stock (the seeds are easy to harvest; just cut the mature flowering stems and place them into a brown paper bag to dry; once well-dried, simply shake and/or gently scrunch the bag to release the seeds from the chaff).
Ever notice that at certain points in the season your tomato flowers seem to be extra full? These double or even triple flowers are sometimes called "megablooms", which occur when two or more flowers fuse together during development. These bear XL fruit which is typically highly uneven in shape but perfectly fine to eat. The cause is not fully understood, but what is known is that megablooms are not usually caused by a disease, instead likely a combination of genetic disposition, environmental conditions and degree of plant maturity. In my experience, large fruiting beefstake tomatoes are by-far the most likely to display megablooms.
The one thing about megablooms is that they need to be pollinated multiple times for the best quality fruit (since they are actually multiple flowers, in one), so if you see these you may want to play a helping hand and encourage of transfer pollen between blooms (with tomatoes, this simply involves gently shaking the flowering stem, then repeating for a couple of days).
Squash and their many cousins (cucumbers, melons, luffas, pumpkins etc) are famous for teasing gardeners with flowers that don't seem to ever develop into fruit. There are two main reasons for this: first, they have separate male and female blooms that are not always in-synch and second, they rely on insects for pollination, and these insects are much more active at certain points in the summer.
The male and female flowers occur on the same plants, but it is very common for cucurbits to start the season by producing only male flowers. This is often described as a practice run, as the plants mature. Later, the female flowers begin showing up - and are easily distinguished because they have what looks like a mini fruit at their base (as in the picture above). Once both male and female are occurring together, bees and other pollinating insects will are able to move pollen from the male flowers over to female blooms... which actually require multiple successful visits by pollen-laden insects to stimulate correct development of the fruit. In fact, it may take up to a dozen well-placed deposits of pollen on a single female flower for fruit to grow properly!
As mentioned earlier, growing conditions impact pollinating insect activity - in particular too hot or too cold will interrupt the movement of these insects - so if you are seeing both male and female flowers but no fruit growing, it could be that the pollinators are sluggish (hand pollination is the solution; best to Google/YouTube this, as it is more involved than tomato pollination).
Any crop that is harvested from under the soil can be a little confusing as to when to dig, so it is helpful to know that flowering in potatoes is a sign the first of your spuds can be enjoyed. The photo above shows the very earliest signs of flowering, so a little too soon to start looking for tubers, but once the blooms are fully opened you can count on tender, tasty new potatoes being ready. Of course, you can also leave the plants to continue developing, allowing the potatoes to become bigger; as long as they are safely tucked into the summer garden and there is no rush to get them out.
If you grow a few different types of potatoes, you have likely noticed that they do not all flower at the same time. In fact, there are early, mid-season and late-maturing varieties. This is one additional reason to use the flowering rule as your guide - if one type is ready it does not mean they all are.
A listener to my CBC Radio call-in recently asked an interesting question, "should I stamp down my potatoes when they flower?" This has to do with the notion that removing the flowers will increase the size and yield of the underground tubers. Unfortunately, there is no clear evidence that removing the flowers on potatoes makes a significant difference in yields. More important areas to focus attention on would be watering potatoes during the warm phase of growth, and mulching to avoid the soil becoming too hot (hot soil = big decrease in yields).
The last crop that we'll cover here is hardneck garlic, another one where there can be confusion about harvest-timing and what the flower-like structure (scape) is all about. First, although the scape looks much like a flower stalk and head, it is in fact a vegetative reproductive structure full of baby garlic clones called bulbils. The development of bulbils does not require pollination and although seed-like, these are essentially very small single garlic cloves; bulbils cab be planted to become full-size heads... but this takes a few years!
Scape development for fall-planted garlic usually precedes harvest time by about a month, so seeing the scapes is definitely not an indicator that it is time to harvest; you'll want to wait until the leaves have started to dry down before digging. But many growers do swear by scape removal as a technique for increasing the size of the final harvest. In my experience, you can harvest wonderful garlic without removing the scapes in July, but there seems to be more support for this practice compared to the removal of potato flowers. The other upside to cutting young scapes is that they are super tasty, particularly sautéed with a little olive oil!
Hopefully this run-through helps answer some of your questions about what is happening in your herb and veggie gardens! Have more questions? I co-host the Grow Guide Podcast, available free on all major podcasting platforms, and also host the weekly gardening call-in show on CBC Radio Manitoba (usually Sundays at 8:35 am).